Planning Requirements for the Conservation of Ahuejote Tree as a

チナンパ世界遺産登録地における重要景観要素としてのアウエホテの保全計画に関する研究
―メキシコ市南部のミルパ・アルタ、トラウアック、ソチミルコに位置する農村地域を対象として―
Planning Requirements for the Conservation of Ahuejote Tree as a Key Landscape Element
in the Chinampa World Heritage Site of Milpa Alta, Tlahuac and Xochimilco, south
Mexico City
レイエス プラタ ハイロ
アグスティン
Jairo Agustin Reyes Plata
2014 年 2 月
Table of Contents
page
CHAPTER ONE
BACKGROUND AND LITERATURE REVIEW
1
1.1 The ancient use of ahuejote in chinampas
4
1.2 The variety of perspectives on chinampas: the habitat of ahuejote
7
1.3 The outstanding value of chinampas in the context of cultural
11
landscapes
1.4 The characteristic features and importance of ahuejote in the
14
landscape character of chinampas
(1) The features and current importance of ahuejote in chinampas
14
(2) Some factors relating to the loss of ahuejote in chinampas
17
1.5 The need of this study
19
CHAPTER TWO
THE METHODOLOGY OF THIS STUDY
20
2.1 Objective of this study
20
2.2 The study site
21
2.3 The characteristics of sources of information
25
2.4 The study units
28
2.5 The organization of this thesis
33
CHAPTER THREE
CITY PLANNIG FRAMEWORK FOR CHINAMPAS
36
3.1 Features of City Land Use and Rural Planning in the regulation of
36
chinampa
(1) Land use policy at a large scale
36
(2) Land Use Policy at a Local Scale
41
CHAPTER FOUR
CHARACTERIZATION OF THE EXISTING CONDITIONS FOR AHUEJOTES IN
44
CHINAMPAS
4.1 Assessment of the key landscape elements in chinampas
44
(1) The density of ahuejote planting in chinampas
44
(2) Water resources and water units in chinampas
46
4.2 Assessment of existing conditions for ahuejote in the rural area in
52
chinampas
(1) The characteristics of land use types in the rural area in chinampas
52
(2) The characteristics of chinampero density
54
(3) The characteristics of crop diversity types
56
(4) The characteristics of open field agriculture types
59
(5) The characteristics of agricultural types
61
4.3 Assessment of existing conditions for ahuejote in the urban area in
63
chinampas
(1) The characteristics of urban density
63
(2) The characteristics of drain cover
66
4.4 Landscape characterization relating to existing conditions of
68
ahuejote in chinampas
(1) The landscape character types relating to existing conditions of
68
ahuejote in the rural area in chinampas
(2) The landscape character types relating to existing conditions of
75
ahuejote in the urban area in chinampas
CHAPTER FIVE
THE MANAGEMENT CATEGORIES FOR THE CONSERVATION OF AHUEJOTE
78
5.1 The legibility of chinampa structure from the distribution of ahuejote
78
5.2 The significance of ahuejote from the landscape character types
80
5.3 The management categories for the conservation of ahuejote
83
5.4 Discussion and conclusions
91
List of tables
List of figures
Notes and references
Annex
CHAPTER ONE
BACKGROUND AND LITERATURE REVIEW
The review of previous studies on chinampas provides the point of reference in discussing
the importance of ahuejote in Mexico City’s landscape. Ahuejote is a tree that has been utilized
in chinampas since pre-Columbian times; therefore, the chapter starts with a sketch of the
historical background of chinampas. This is followed by an exploration of the studies that today
integrate the different visions on chinampas. A key message here is that the preservation of
ahuejote relies on the management of chinampas as a site of multiple values and complexities.
Afterwards, the chapter centers on describing the features of ahuejote, its contributions to
chinampas, and the problems that it faces. The chapter ends with the argument of the need of
this study for the preservation of ahuejote.
Literature review included references about chinampas in articles, thesis, technical reports,
and journals online from Mexican and international databases, such as Sciencedirect.com and
the network of Scientific Journal for Latin America and the Caribbean, Spain and Portugal
(Redalyc.org). The search also included the online collections of libraries from the National
University of Mexico (Spanish: Universidad Nacional Autonoma de Mexico), the National
Institute on Agricultural, Forestry and Livestock (Spanish: Instituto Nacional de Investigaciones
Forestales, Agricolas y Pecuarias), the National Institute of Ecology (Spanish: Insituto
Nacional de Ecologia) and the Universite Paris IV-Sorbonne (France).
Literature in Spanish, English and French languages was gathered, selected and organized
into five thematic groups as shown in table 1-1: Agriculture, History, archeology and heritage,
Land use, urbanization and planning, Ecology, and Water. Table 1 contains an overview of
articles on each thematic group. Additionally, keywords relating to each thematic group were
identified.
1
Table1-1 Selected literature relating to chinampa
Author
Language
Literature
sort
Content summary
1) Agriculture
Keywords: agro-ecosystem, agricultural diversity, human management, greenhouse, chinampero
Losada et al. ,(2011)
English
Article
Characterization of agricultural systems in the suburban and
peri urban areas of the south of Mexico City.
Soriano-Robles et al.,
(2010)
English
Article
Evaluation of energy flows and efficiency of the chinampa
system.
Soriano et al., ( 2002)
English
Article
Assessment of the economic performance of chinampa
regarding its agricultural diversity.
Losada et al., (1998)
English
Article
Changes of urban agriculture over time in the south of
Mexico City.
Gonzalez –Jacome, A.,
(1993)
English
Article
Characteristics of traditional agro-ecosystems in the central
Mexican high lands.
Jimenez-Osorio J.J. and
Gonzalez-Pompa, A.,
(1991)
English
Article
Human management of crops and its impact on the
conservation of agricultural diversity.
2) History, archeology and heritage
Keywords: land reclamation, chinampa, monument, culture, heritage
Gonzalez, A. at al.,
(2010)
Spanish
Book
Catalogue of chinampas in San Gregorio Atlapulco.
Sanchez, A., (2008)
Spanish
Book
Recompilation of historical essays on chinampa
Terrones, E. et al.,
( 2004)
Spanish
Book
Historical recompilation of politic, urban and environment
aspects in Xochimilco. Period 1929-2004 years.
Peralta, A. at al. ,(1992)
Spanish
Book
Catalogue of architectural and urban monuments in
Xochimilco.
Armillas, P., (1971)
English
Article
Archeological research to verify the historical data on the
development of Aztec Land Reclamation in the Valley of
Mexico.
3) Land use, urbanization and planning
Keywords: wetland, urbanization, informal settlements, land use change, land use policy
Aguilar, A.
(2013)
et al.,
English
Article
Estimation of ecosystem services from suburban wetland
(chinampa) in Mexico City.
( to be continued in next page)
2
Table 1-1 Relevant bibliography relating to chinampa (comes from previous page)
Author
Language
Literature
type
Contents
3) Land use, urbanization and planning
Wigle, J., (2010).
English
Article
Policy on the management of irregular settlements in the
conservation land on Mexico City based on the study of the
Program of Urban Development in Xochimilco
(Xochimilco borough).
Wigle, J., (2009).
English
Article
Study on the social dynamics of informal human
settlements based on the case study of Ampliación San
Marcos (Xochimilco borough).
Clauzel, S., (2008).
French
Doctorate
Thesis
Comparative study on the dynamics of land occupation and
land use changes in the urban wetlands of chinampa
(Mexico) and hortilonnages d’Amiens (France).
UNESCO,( 2006)
Spanish
Book
Memory of the Master Plan for the World Heritage Site
Milpa Alta, Tlahuac y Xochimilco.
Ezcurra, E.,(2010)
Spanish
Book
Memory on the urbanization of the Basin of Mexico
4) Ecology
Keywords: ahuejote, malacosoma, muerdago, pollution, chinampas
Spanish
Anda, R., &Villa, A.
Dasometric, phenological and sanitary study on ahuejote
Article
(1991)
(Salix bonplandiana) in Xochimilco
Spanish
Stepahn Otto, E., (1993)
Book
Varying aspects of ahuejote in the chinampa.
Outerbridge, T., (1987)
English
Article
Historical outline of chinampa and its decline over time
5) Water
Keywords: aquifer, overexploitation, land subsidence, wetland, lake, environmental decline
Environmental and administration issues on water security
Oswald, U., (2011)
Article
English
in the Metropolitan Valley of Mexico City.
Ortiz, D. del C. and
Origin and evolution of a new lake in Tlahuac and its
Article
English
Ortega, M.A., (2007)
implications for land subsidence and flooding hazards.
Excurra, E. and
Population growth and environmental decline in the basin
Mazari-Hiriart, M.,
English
Article
of Mexico
(1996)
Gonzalez-Moran, T.
Environmental issues related to water abstraction in the
Rodriguez, R. and
English
Article
basin of Mexico.
Cortes S.A., (1999)
Mazari, M. and Mackay,
Article
Potential for groundwater contamination in Mexico City.
English
D.M., (1993)
Durazo, J. and
Evolution of groundwater regimens in the Valley of Mexico
Article
English
Farvolden, R.N.,(1989)
based on the review of historical evidence.
3
1.1 The ancient use of ahuejote in chinampas
Ahuejote is a tree that was utilized in the construction of chinampas. Chinampa is a method
to reclaim land for agriculture purposes on swamps. Archeological studies indicate that
chinampas were structured in the Basin of Mexico in pre-Columbian times 11).
In the 16th century, five shallow lakes, between 800 and 1000 km2, covered the Basin of
Mexico. As illustrated in fig.1-1, the two lakes in the North were called Zumpango and Xaltocan,
the two lakes in the South were known as Xochimilco and Tlahuac, and the lake in the Center
was called Texcoco. The Basin of Mexico is an endorheic basin; therefore, the lakes used to join
often as a single body of water during the rainy season of high water levels and tended to
separate into individual bodies of water in the dry season. As can be seen in the scheme of lakes
levels in the fig.1-1, Lake Texcoco was the lowest of all lakes, so water drained ultimately
towards it.
Fig.1-1 Chinampas in the Basin of Mexico in the 16th Century
(Map based on Armillas Gil, I. et al. (2010). p. 53) 12)
4
Lakes Xochimilco and Chalco formed part of a subbasin in the south of the Basin of Mexico.
The lakes covered 148 km2 of a shallow plain that were fed by freshwater and contained plenty
of wildlife and lush aquatic vegetation.
To control the water levels in lakes, Aztecs conducted large efforts to construct various sorts
of waterworks, such as waterways, dikes, aqueducts and chinampas. Tlatoani acolhua
Nezahualcoyotl
67
, an Aztec emperor, built a dike that divided Lake Texcoco in two districts,
east and west. The west District, where the capital of Aztec Empire, Tenochtitlan, was located,
was named Lake Mexico. With the new organization of lakes, Lake Mexico remained linked to
the southern lakes Xochimilco and Chalco, from freshwater was found. The communication
among those three lakes (Mexico, Xochimilco and Chalco) was supported by a series of canals
and bodies of water that provided direct routes of transportation to Tenochtitlan.
In the 16th Century, the chinampa region covered approximately 120 km2 in Lakes
Xochimilco and Tlahuac. Chinampa plots covered 9,000 ha. Canals and other bodies of water
occupied the remaining surface
11)
. At the time of Spanish contact (1521), Tenochtitlan had 12
2
km in extension. Its population reached 150, 000 to 200,000, who annually demanded 30,000
to 40,000 MT (metric ton) of maize to cover nourishment needs 12). To supply the need of such
size, chinampas were employed as part of a food production system that contributed to the
agricultural self- sufficiency in the city region 35).
The horticulture system in chinampas annually produced 20,000 MT of maize to nourish
some 100,000 people in Tenochtitlan
12)
. The high productivity of chinampa horticulture was
34)
because of the use of almacigo , a seedbed that was utilized for germinating vegetable seeds.
Almacigo was an Aztec innovation that allowed intensive cycles of production all year. Some of
the crops that were cultivated in chinampas included corn, tomatoes, chili, cabbage, bean and
flowers 67).
Another factor that contributed to the productivity of chinampas was the chinampa itself.
Chinampas were designed to be narrow to capture moist permanently at root level. As can be
seen in fig.-1-2, chinampas were surrounded by canals, which worked similar to an irrigation
system. Studies
11), 12), 61)
describe that the first step to make a chinampa was to locate a
foundation or ‘cimiento’ near a lake edge with shallow depth, around 2.52 to 3.36 meters. A
rectangle of about 6 to 9 meters was then marked to define the chinampa boundaries. The next
step was to create a dense organic bed or ‘cesped’ by piling vegetation cut from the lake edges.
Mud from the lake bottom was piled on top of cesped to raise the chinampa to about 0.84 meters
above water. The chinampa’s edges were reinforced by branches and ahuejotes, which are
planted all around, 4 to 5 meters along the edges. Ahuejotes grew rapidly and fixed the
chinampa to the bottom, preventing terrain from eroding. The chinampa was then ready for
agriculture.
.
5
Fig.1-2 Scheme of chinampas
Drawing by Cathya Guzmán Herrera
The construction of chinampas supposed the landscape transformation of lakes in the Basin
of Mexico. An illustration by Miguel Covarrubias helps visualize the chinampas as seen in the
basin of Mexico’s horizon in combination with lakes, mountains and other waterworks.
Chinampas formed a singular sort of land use that reflected a model of a city based on the
comprehension of water conditions in the basin of Mexico City 23). For example, in Tenochtitlan,
the chinampas were separate properties, which contained a house, a garden, and ahuejote trees
that surrounded the chinampas. Ahuejotes became a characteristic element of chinampa land use
and, as a consequence, a key element in the composition of chinampa landscape character.
Today, some 2,440 ha of chinampa remnants can be seen in the south of Mexico City. The
ahuejote is still the tree of chinampas.
6
1.2 The variety of perspectives on chinampas: the habitat of ahuejote
The review of previous studies on chinampas prepares the terrain to approach to the
complexity of ahuejote’s settings.
In the beginning of the 1970s, the investigations focused on documenting the archeological
evidence of chinampas in the basin of Mexico. The studies conducted by Armillas (1971) 11) in
the south of Mexico City, based on aerial photos and field work, noted that chinampas consisted
of a land reclamation method, which was utilized by pre-Columbian civilizations, to expand
farmland over the ancient swamps and lagoons in the Basin of Mexico. His work indicated that
chinampas represented an exceptional example of native technology used in wetland conditions.
Armillas contributed to comprehend that chinampas had a strategic role in the florescent of
Aztec civilization, and they were utilized in the reorganization of the landscape in the south of
the basin of Mexico (See this chapter, section 1.1).
Armillas Gil et al. 12) cites that contemporary studies of Armillas, conducted by Calnek
(1972), Coe (1974), Sanders at al. (1979) and Parsons et al (1982), were systematically adding
new archaeological evidence that confirmed the presence of chinampas in many places across
the basin of Mexico, but that the only chinampa remnants were localized in the south of Mexico
City, particularly in Xochimilco.
In 1986, the Mexican authorities recognized the importance of preserving chinampas and
pre-Columbian towns through the designation of the “Historical Monument Zone in Boroughs
Xochimilco, Tlahuac and Milpa Alta” 30) (Spanish: Zona de Monumentos Historicos de las
delegaciones Xochimilco, Tlahuac y Milpa Alta”). The zone covered an 86.63 km2 area,
including chinampas and twelve towns from pre-Columbian origin.
Using the 1986 designation as basis, the Mexican authorities proposed Xochimilco to be
included in the World Heritage List in 1986. UNESCO accepted the nomination and, as will be
detailed in this chapter, section 3, Xochimilco and the Historical Center of Mexico City were
designated as a World Heritage Site in 198785).
The designation of chinampas as a World Heritage Site in 1987 witnessed a growing interest
in chinampas. The 1987 designation stated the vulnerability of chinampas to environmental
decline and argued the need of protecting traditional chinampa agriculture. A report by
Outerbrigde (1987)
61)
noted, for instance, the disappearance of chinampas due to water
pollution, the introduction of mechanized agriculture systems for cultivation, and urban
expansion.
Studies conducted by Ezcurra (1990)
26)
25)
, Mazari and Mackay (1993)
Mazari-Hiriart (1996) , and Gonzalez-Moran et al. (1999)
38)
48)
, Ezcurra and
often referred to water problems
in Xochimilco as a consequence of unsuitable schemes of water management in the basin of
Mexico. Their studies reveal that water management in the basin of Mexico is technically a
7
combination of overexploitation of the aquifer, low rate of groundwater recharges, high supply
costs, inefficient reuse of water and a complex system of water distribution.
The management of water has affected agricultural activities in chinampas. A historical
research conducted by Arechiga 10), for instances, noted that 1901 saw the beginning of the
exploitation of the springs in Xochimilco and the construction of an aqueduct to supply water to
the center of Mexico City. The water exploitation provoked the depletion of the springs. In 1957,
the water table of canals had dropped and it caused navigation difficulties. In response, city
authorities started with the supply of treatment water to the chinampas to recover the water table
in canals in 1959. Treatment water contained high concentrations of organic matter, provoking
the proliferation of exotic plants such as Ecchornia crasipes (Spanish common name: lirio
acuatico) along canals. Since then, chinampas are supplied with water from treatment water
plants.
In 1989, after the World Heritage Site designation, the Federal Government of Mexico
launched the ‘Plan for Ecological Rescue of Xochimilco’ as part of an official initiative to create
water reservoirs and recreation facilities on the north of Xochimilco to enhance water
management. With this move began a period of plans marked by ecological approaches to the
management of chinampas, at least in paper.
In 1992, as an effort to conserve chinampas in Xochimilco, the Mexican authorities signed a
decree on the creation of the Natural Protected Area (or natural reserve) “Ejidos de Xochimilco
and San Gregorio Altlapulco”
30)
(Spanish: Area Natural Protegida sujeta a conservacion
ecologica “Ejidos de Xochimilco y San Gregorio Atlapulco”). The decree provided the first
planning framework of management of chinampas. Its ecological approach centered on
protecting chinampas and wetlands as priority sites for the generation of environmental benefits,
for instance, aquifer recharge and climate regulation 30). The decree demanded the promulgation
on a site plan for the management of the natural reserve within a short period (3 years); however,
the site plan was delayed until 2006, 14 years after the decree66).
A further parallel theme in the study of chinampas is the chinampa agriculture. The first
studies on chinampa agriculture often denote the efficiency and self-sustaining qualities of
traditional agriculture methods in chinampas.
Traditional chinampa agriculture is described as a polyculture system that wisely integrates
the use of own natural elements, such as water, soil and plants, into the agriculture process 34), 37).
Polyculture features a wide variety of crops under a scheme of rotation based on the use of the
almacigo, which is a seedbed. As shown in fig.1-3, the formation of the almacigo (1) begins
with digging a shallow trench on a chinampa plot. Next, (2) the chinampero takes out agua-lodo,
which is mud rich in organic matter from the canal bottom, and it includes the waste of plants
that grow in chinampas, like ahuejote. (3) The mud is cleaned of any garbage, plants or roots
8
and poured onto the trench until it is completely filled. (4) The mud is left for two to three days
until it dries to the consistency of a gelatin. Then, (5) the mud is carefully marked into squares
with a string and cut along the lines with a large knife to form cubes known as ‘chapin’. (6) A
hole is poked in each ‘chapin’ and a seed is dropped into each hole. (7) A fine layer of manure is
spread on the almacigo. When the seeds have germinated, (8) plants are taken from the
almacigo and transplanted to the chinampa, where they will continue their growth. Thus the
chinampero, the chinampa peasant, can begin working on the next crop while waiting for the
harvest of the current one.
Fig.1-3. Use of almacigo in chinampas
(Photos 1,2 and 6 by David Jimenez from ‘La casa de la chinampa’, photos 3-5 and
( by the author)
Crops with different growth cycles can be sown on the same chinampa but harvested at
different times. Crop rotation introduces biomass in soil, helping the maintenance of its fertility
and, as a consequence, contributing to the success of chinampa agriculture
37), 46)
. Traditional
chinampa agriculture also involves a high level of biodiversity because the management of
many different domesticated and non-domesticated plants that grow in the plots or nearby
canals 46).
9
With the decline of environmental conditions, recent studies focus on evaluating the
efficiency of traditional agriculture in face of the introduction of new methods for cultivation in
chinampas. For instance, a study conducted by Soriano-Robles et al. (2010) 81) noted that, in
comparison with other agricultural methods to chinampas, such as greenhouse and dairy cattle
units, traditional agriculture is shown to be more efficient. They evaluated the energy flows of
each agricultural method and found that agricultural methods that recycled own wastes had
better energy efficiency. In this line, Merlin-Uribe (2009)50) compared the economic profitability
and ecological sustainability of traditional chinampa agriculture and greenhouses. He found that
the benefits that chinamperos obtained from agriculture depended on the investment in
agricultural inputs. Greenhouse agriculture required high levels of investment in agricultural
supplies to start the productive cycle in comparison to traditional agriculture. The economic
profit from greenhouses appeared to be higher than the chinampa’s. However, greenhouses
highly depended on external inputs to generate such profit, whereas traditional agriculture
utilized the materials that had in chinampas. Merlin-Uribe concluded finally that the traditional
chinampa agriculture resulted to be more ecologically sustainable.
Latest studies on chinampas focus on the identification of land use changes and the local
dynamics of land occupation. Studies on urbanization confirmed that city plans have been
overwhelmed by the urban pressure on chinampas even if there were many designations and
plans to protect chinampas. A study conducted by Clauzel (2009) 18) investigated the evolution
of the chinampa land use types in the boroughs of Tlahuac and Xochimilco between 1974 and
2004. Her study, based on photo interpretation, showed that chinampas changed from 2,745 ha
in 1974 to 1437 ha in 1994, and reduced to 1329 ha in 2006. On one hand, changes such as
those indicated a 48.41% reduction of chinampa area. On the other hand, it showed the
diversification of chinampa land use during the last decades. Her results showed that chinampas
changed from a land that was essentially dedicated to agriculture in 1974 into multiple land uses
in 2004. Changes implied that agriculture modes were diversified, abandoned land was extended
and urbanization was increased.
In 2012, Merlin-Uribe et al. 51) quantified the changes of land uses and land cover through a
satellite image analysis on chinampas and wetlands in Xochimilco from 1989 to 2006. They
identified different types of urban, agricultural and natural land use covers. Their conclusions
showed that changes from natural or agricultural land use to urban land use frequently occurred
indirectly. Agricultural land use firstly changed to greenhouse agriculture or abandoned
agricultural land, and then, urbanization occurred. They used a projection model to forecast
potential sceneries of urbanization in chinampas in Xochimilco and concluded that full
urbanization of chinampas will happen within the next 17 years.
10
1.3 The outstanding value of chinampas in the context of cultural landscapes
The Chinampa was one of the first Mexican sites inscribed in the World Heritage Site List in
198785). Its nomination, under the name of Historic Center of Mexico City and Xochimilco,
included two cultural properties at one site, the Chinampa and the Historic Center of Mexico
City. The Historic Center of Mexico City includes an archeological site, the Templo Mayor,
which proves the existence of Tenochtitlan, the capital of the Aztec Empire during the
Pre-Columbian era. Furthermore, the Historic Center presented an array of colonial monuments
that were witnesses of one the most remarkable occurrences in Mexican History: the Spanish
Conquest in 1521. On the other hand, Xochimilco, the “Venice of the New World,” 85) was the
only site with chinampa remains in Mexico City. The Historic Center of Mexico City and
Xochimilco, separately but as a whole, illustrate different aspects of the evolution of the
societies that settled on the Basin of Mexico.
As aforementioned in this chapter, section 1.1, Aztecs created a singular sort of land use
with the utilization of chinampas. The singularity of that land use is where the chinampa’s
Outstanding Universal Value resides 86). The Historic Center of Mexico City and Xochimilco site
was designated a World Heritage Site on the basis of the cultural criteria (ii), (iii), (iv), and (v),
as shown in table-2-1. The first three criteria (ii, iii, iv) were applied to the Historic Center of
Mexico City and the last one (v) to chinampa. Criterion v expressly mentions “the lacustrine
landscape of Xochimilco constitutes the only reminder of traditional ground occupation in the
lagoons of the Mexico City before the Spanish conquest” 85).
Table-1-2 Links between the cultural heritage criteria, cultural landscape
categories and cultural criteria of nomination of chinampa
Cultural criteria
(i)
(ii), (iii), (iv), (v)
(vi)
Cultural landscape categories 88)
Clearly defined landscape
Organically evolved landscape
A relict (fossil) landscape
A continuing landscape
Associated cultural landscape
Cultural criteria for the nomination of the
Historic Center of Mexico City and
Xochimilco 85)
(ii), (iii), (iv), (v)
Some entities and scholars are of the opinion that chinampas should be included within the
category of cultural landscapes because they reflect both natural and ecological values at one
site
36), 85)
. In 1987, when the designation of World Heritage Site occurred, the World Heritage
Convention had not yet adopted such category of cultural heritage88). Therefore, in 2008, the
Mexican authorities proposed to change the name of the 1987 World Heritage Site to Historical
Center of Mexico city and the cultural landscape of chinampero de Xochimilco, Tlahuac and
Milpa Alta87). The proposal was not approved by the World Heritage Convention. The idea of
11
changing the name of the Heritage Site emerged with the Master Plan for the World Heritage
Site of Milpa Alta, Tlahuac and Xochimilco in 2006. In that plan, a team of experts had
envisioned the management of chinampas in the context of the cultural landscapes.
In the framework of the World Heritage Convention, the term cultural landscape is
employed to describe the “combined works of nature and of man” that are clearly associated,
geographically and culturally, to a region and its people 88). That understanding states at least
three key aspects about cultural landscapes. The first one is that cultural landscapes possess
distinctive attributes that are associated to a specific place. Secondly, people make use of those
attributes. Lastly, they mutually interact to create a distinctive landscape.
The World Heritage Convention, recognizing the varying landscape forms that could result
from the interaction between culture and nature, accepts three categories of World Heritage
cultural landscapes: 1) Clearly defined landscapes, 2) Organically evolved landscape, and 3)
Associated cultural landscape88). The chinampas meet the characteristic of a continuing
landscape because they still keep some significance in the way of life of many people in Mexico
City. Schulze and Caraballo73) note that chinampas remain alive due to their cultural utilization
for agricultural purpose. It is the life around the agriculture that provides the Outstanding
Universal Value of chinampas as World Heritage Site.
In the context of the World Heritage Convention, the Universal Outstanding Value of
cultural landscapes is assessed on the basis of two qualities: authenticity and integrity. For the
interest of this research, the discussion here will focus on integrity.
According to the Handbook for conservation and Management on World Heritage Cultural
Landscapes, integrity is the “wholeness, completeness, unimpaired or uncorrupted condition,
continuation of traditional uses and social fabric”88). Recognizing the wholeness or
continuation of traditional uses in cultural landscapes is quite a challenge because they change
continuously. Antrop (2005)9) argues that a cultural landscape is reorganized many times in
order to adapt its use and spatial structure better to social demands. He illustrated that with the
case of agricultural landscapes. In an agricultural landscape, famers have to adapt their
production to social demands and environmental changes to obtain an economic benefit. With
any new adaptation, they transform landscape, sometimes positively and sometimes negatively
as well.
In a cultural landscape of heritage value, it would be crucial, therefore, to discern the ways
as any adaptation happens to maintain the heritage integrity and, as consequence, the
Outstanding Universal Value. In chinampas, any adaptation would imply recognizing the
lacustrine origin of site to keep the physical conditions in which essential chinampa elements
can be conserved. Many cultural landscapes contain habitats for the conservation of biodiversity
that are essential to keep traditional land use, and chinampas are an example of it.
12
Another aspect of integrity in cultural landscape is that all sites’ parts must save their
relationship with the whole landscape88). Although landscape organically changes, it should
transmit coherence creating a familiar scenery to people. For example, if a landscape element is
seen as alien to a site, people can feel disconnected from the landscape.
Assessing the integrity of cultural landscape is still a subject to be appropriately studied in
Latin American countries. The report for Latin America and the Caribbean in 2008 prepared by
the World Heritage Committee74) revealed that one of the reasons of the low representation of
Cultural Landscapes in the Latin-American and Caribbean region was the weakness to
formulate acceptable parameters to assess the state of conservation of cultural landscapes.
Compared with the European region, where there were 37 sites (58%), and the Asia Pacific
region, with 13 sites (20%), the Latin-American and Caribbean region had only 4 sites (6%)
inscribed as cultural landscapes by 2009.
In 2011, the Mexican Society of Landscape Architects launched the Mexican Charter of
Landscape79) as an initiative to outline some principles for the conservation of Mexican
Landscape Heritage, natural and cultural. The Charter emphasizes the diversity and public
character (public good) of landscape as a key element for individual and collective welfare; as a
human right of enjoyment; and as an object relating to sustainable development. The Charter
retakes the definition of cultural landscapes proposed for the World Heritage Convention of
UNESCO, but, at the same time, it states the need of investigating and researching the typology
of Cultural Landscape acceptable to the Mexican Context.
13
1.4 The characteristic features and importance of ahuejote in the landscape
character of chinampas
(1) The features and current importance of ahuejote in chinampas
Amongst the trees in Mexico City, the ahuejote (Salix bonplandiana) is one of the trees
catalogued as heritage tree according to the Law on Safeguard of Architectonic Urban Heritage
in Mexico City ( Spanish: Ley de Salvaguarda del Patrimonio Arquitectonico Urbanistico del
Distrito Federal)28). Heritage trees are commonly protected as exemplary individuals that
survived over time and that are treasured and protected by special status of attention. The Law
of Safeguard gives tree species, rather than individual trees, a status equivalent to natural
monuments. Heritage trees in Mexico City are species that pose some importance, for instance,
historical, technological, scientific, aesthetical, or artistic, and those must be bequeathed to
future generations. Ahuejote is in that sense an exemplary specie of tree with long history in
Mexico City.
Ahuejote is a willow tree native to Mexico. It grows across canals in chinampas in the south
of Mexico City, between 2250～2500 meters above the mean sea level1) , 68). Ahuejote’s name
comes from the nahuatl words: atl (water) and huexotl (willow) 53). As can be seen in fig.1-4,
outside of the Basin of Mexico, ahuejote is distributed from the south of New Mexico and
Arizona to Guatemala68).
Ahuejote is fast-growing, but relatively short-lived (20 to 30 years)14). It regenerates
biomass quickly and propagates easily by hard-wood cutting. With the construction of
chinampas, ahuejote was domesticated and wisely used to support chinampa agriculture. Peralta
and Rojas (1992) mentioned the practice of planting ahuejotes as a prerequisite to begin the
cultivation of chinampas 64).
Ahuejote has many qualities that support chinampa agriculture. As can be seen in fig.1-4,
photo 2, it has a slender, rounded crown, and branches that drop toward the ends. Its crown is
tall rather than broad (6 to 10 m. tall or taller (15 m.), 1-5 m. wide, 40 to 80 cm in diameter) 14).
These characteristics of ahuejote meet the spatial needs of cultivation in chinampas. Ahuejote is
planted to form a natural barrier against storms and winds while controlling the penetration of
the rays of sunlight for crops. Since chinampas are commonly narrow strips surrounded by
narrow canals, the columnar form of ahuejote is also suitable for free navigation across canals11).
Ahuejote has a diffused fibrous system similar to a net that helps to stabilize chinampas
edges, as can be seen in fig.1-4, photo 3 .As was described in this chapter, section 1, the layout
of chinampas is designed to capture moisture. The porosity of the soil and narrowness of
chinampas plot allowed the seepage of water from canals to keep the soil permanently moist
even through the dry season. Ahuejote avoids the erosion of soil while keeping the chinampa
moist.
14
In fig.1-4, photo 4 shows that ahuejote has simple, and thin leaves. Its leaves are 6 to 15
centimeters long and 1 to 2 centimeters wide, colored yellow-green above and silvery white
below14). Ahuejote is semi-evergreen tree14). 5-year-old ahuejotes generate about 50 kg biomass.
In the canals of chinampas, it is often observed how some ahuejotes’ leaves drop and are
captured in the form of organic matter, which is reutilized in fertilization or for leveling
chinampa. Canals are constant supplies of complementary natural fertilizers like manure or
other wastes of crops.
The fig.1-4, photo 1 illustrates that ahuejotes form a forest in chinampas. The ahuejote forest
helps create the agro-ecosystem of chinampas. The ahuejote interacts with water and soil
through agriculture and contributes to the generation of environmental services, for example, the
biodiversity of chinampas 46).
Fig.1-4 Ahuejote features
(Photos 1 and 2 by the author;
photos 3 and 4 by David Jimenez from ‘La casa de la chinampa’
Ahuejote acts as a pioneer plant that helps to establish many aquatic and subaquatic plants
that grow on chinampa borders and surroundings. Some of the plants are:
1. Aquatic plants. This group includes floating types that can be seen on canals and
15
lagoons. Lentejilla (Lemma minuscula), chilacastle (Wolffia columbiana) and lirio
acuatico (Eichornia crassipes) represent this group the most. Among them, the lirio
acuatico is quite proliferated in water surroundings, where it frequently obstructs
canoes’ navigation. Other aquatic plants are berro (Berula erecta), atlanchan (Cuphea
angustifolia), hierba del cancer (Lythrum vulneraria), carrizo (Phragmites australis),
legucha de agua (Pistia stratoites), chichicastle (Lemma gibba), ninfa (Nymphae
mexicana) and so on. Ninfa is a native plant to Mexico, which is under threat
according to the NOM-059-SEMARNAT-200130).
2. Sub-aquatic plants. These include varying species of reed plants, such as Typha
latifolia and Schoenoplectus tabernaemontani. Reeds grow two to three meters in high
and near chinampa edges. Many groups of reed serve as a habitat of animals.
3. Tree species. Trees beside ahuejote include ahuhuete (Taxodium mucromatum) and
exotic species, such as sauce lloron (Salix baylonica), trueno (Ligustrum lucidum),
araucaria (Araucaria heterophylla), jacaranda (Jacaranda mimosaefolia), causarina
(Casuarina equisetifolia) and eucallipto (Eucalyptus spp.).
Ahuejote has cultural significance for Mexicans, particularly for the persons in the south of
Mexico City. Many of them have literally grown up watching ahuejote. Chinampas are the
working space where chinamperos spend time the most. Therefore, the ahuejote is part of their
daily surroundings. Some chinamperos are attached to ahuejotes. For instance, Rodolfo Cordero
Lopez 20), native to Xochimilco, narrates the creation of ahuejote in a mythic legend on life on
earth. Water, ahuejote, gods and other characters meet together in a history that reflects how
ahuejote is part of the memories of many people.
Other people know the ahuejote because they have visited chinampas for sightseeing.
Chinampas in Xochimilco and Tlahuac have been main tourist spots in Mexico City since the
beginning of the last century. Caraballo & Leal
16)
mentioned that people felt attracted to
Xochimilco because of the rural atmosphere that chinampas, canals, crops and mountains
inspire. In 1937, for instance, the Ritz Hotel, one of the main international hotels in Mexico City,
had a mural painted by Miguel Covarrubias in which he portrayed the lively atmosphere of
music and food that amazed visitors, national and international, in Xochimilco. A Mexican film
by Emilio “El Indio” Fernandez” in 1943 also captured the magical atmosphere in chinampas.
With that film, the internationalization of Xochimilco occurred, Caraballo and Leal added.
Ahuejote has been passed on to be part of the collective memory of Mexicans for many
means through stories, paintings or films, but it is always associated with the chinampas.
However, the continuity of ahuejote as a key feature in chinampas today is threatened by the
new forms of land uses.
16
(2) Some factors relating to the loss of ahuejotes in chinampas
Ahuejotes in chinampas are mainly stressed by land use changes. The conversion of rural
land uses into urban land, or the transformation of agricultural methods causes the gradual
decline of environmental conditions where ahuejotes grow. Studies also report the pollution of
water and soil resources, deforestation and the introduction of exotic plants with the
urbanization.
Ahuejotes are sensitive to pollution and are susceptible to plagues, mainly insects, and
amongst them are Aculops tetranoyhrix, Cladocolea loniceroides, Malacosoma incurvum,
Hylaea punctilaria, tuberolachnus, and Paranthrene dollii8). A forestry study estimates that
80 % of ahuejotes were affected by some plagues18). In fig.1-5, photo 1 shows the worm,
Malacosoma incurvum var. aztecum, a plague to ahuejote. A study 65) reports the defoliation out
season by the presence of malacosoma, on the basis of a sanitary evaluation in a population of
682 ahuejotes (Salix bonplandiana). The same study investigated the habitat conditions for
ahuejote in four types of land use (12ha): agricultural, urban, touristic and abandoned land use.
It is observed that 70 % of ahuejotes that grew in abandoned land use were plagued compared to
20% of ahuejotes in the agricultural land use. Study findings indicated healthy trees are
associated with human intervention focused on the management of plagues. Trees that grew up
in agricultural and touristic types of land uses were better formed and healthy in comparison to
the trees in urban and abandoned land uses due to the absence of care. Furthermore, the study
reports that ahuejotes in urban land use area were inferior in height and trunk diameter and
showed a major incidence of mechanical damages in trunks and branches.
Another plague to ahuejote is muerdago, which can be seen in fig.1-5, photo 2. Muerdago
(Cladocolea loniceroides) is a hemiparasite plant that grows on trunks or branches and that can
wither ahuejote. A study8) recorded that 17,324 out 24,908 ahuejotes were affected by muerdago
in 2002.
Fig.1-5 Some plagues that affect ahuejote
(Photos 1 and 2 by the author)
17
The introduction of exotic species replaces ahuejote. There is a record of at least 9 exotic
species of trees in chinampas, for example, Schinnus molle, Ficus bejamina, Ficus retusa, Ficus
elastica, Eucaliptus camandulensis, Buddleia parviflora
30), 65 )
. Some of them, like Eucaliptus
camandulensis, show allopathic effects on soil and agriculture.
A further stress factor of ahuejote is the practices of some agriculture methods. Agricultural
methods can change the functional relationship between the agriculture and ahuejotes. Some
study conducted by Merlin-Uribe50) noted an inferior density of ahuejotes in chinampas devoted
to greenhouse agriculture. Based on a questionnaire survey conducted to 100 chinamperos in
two chinampas districts in Xochimilco south, it was found that chinamperos that practice
traditional agriculture attributed major importance and gave attention and care to ahuejote. 90%
of chinamperos were reported to be periodically involved in pruning practices to control shade
and avoid the propagation of plagues among ahuejotes. In contrast, chinamperos devoted to
greenhouses agriculture appear to show few (30%) or no (38%) importance to have ahuejote in
chinampas and to take care of the management of ahuejotes.
18
1.5 The need of this study
The focus of the studies on chinampas has moved from describing their characteristic
features as cultural heritage towards stating the need of finding better mechanisms for their
conservation. The complexity of comprehensively managing chinampas is illustrated by the
multiple visions that exist about them. Researches note environmental decline and a progressive
reorganization of chinampa land use due to the advance of urbanization and the diversification
of land use types.
The reorganization of land use types implies an alteration of the physical elements in
chinampas. The ahuejote is one of the key elements that compose the basic physical and visual
structure of chinampas and consequently, it is related to the character and quality of the
chinampa landscape. With the transformation of land use conditions, ahuejote is remaining as a
common physical element to different types of land uses. With that transformation, some of the
traditional relationships between ahuejotes and chinampas change. Some just disappear, but at
the same time, new relationships appear. For instance, the prime functional relationship between
ahuejotes and chinampas based on traditional agriculture is faced today with methods of
production that leave beside the use of ahuejotes in chinampas. On the other hand, the
urbanization of chinampa land use indicates the presence of new factors in the relation of
chinampas and ahuejotes.
The loss of ahuejotes implies an alteration of the chinampa scenery, which is a part of the
regional identity in the south of Mexico City. Therefore, the need of clarifying the new
conditions where the ahuejote grows is to be investigated in order to conserve it as a key
element of the chinampa landscape.
19
CHAPTER TWO
THE METHODOLOGY OF THIS STUDY
2.1 Objective of this study
Ahuejote (Salix bonplandiana) is a willow tree native to Mexico, and its habitat is in
chinampas within the World Heritage Site of Milpa Alta, Tlahuac and Xochimilco, south
Mexico City. The origin of chinampa goes back to remote times, when Aztecs created
chinampas as a land reclamation system for agricultural purposes on the ancient lakes in the
Basin of Mexico. Since then, the ahuejote plays a key role in chinampas, and today, still keeps a
social and symbolic significance for Mexicans.
With environmental decline and urban pressure, the land use in chinampas is changing and
with it, the essential attributes that have defined the chinampa landscape. The chinampa
agriculture that traditionally incorporates the use of ahuejote struggles to survive and continue
being functional. The change of land use is also linked to urbanization; people are abandoning
agriculture. The prime relationship between ahuejotes and chinampas based on agriculture is
either diminishing or transforming. New forms of land occupation are appearing with the urban
expansion. Yet notwithstanding these changes, the ahuejote is a key element to have and to
maintain in order to conserve the identity of chinampas.
Therefore, the objective of this study is to investigate the potential conditions to conserve
ahuejotes as a key heritage landscape element in the Chinampa World Heritage Site of Milpa
Alta, Tlahuac and Xochimilco, south Mexico City. The study approaches ahuejotes as a heritage
tree in a heritage site associated with agriculture. The study is based on the landscape
characterization and the establishment of planning parameters, historically and ecologically,
associated with chinampas through assessing the existing conditions of water resources,
agriculture land use and urban land use. Furthermore, the study aims to establish some
management categories for the conservation of ahuejotes.
20
2.2 The study site
The study site focuses on 1,821 ha of chinampas, 18 km away from the center of Mexico
City. Fig.2-1 shows that the chinampas cover expanses in the boroughs Xochimilco and Tlahuac,
from northwest-center Xochimilco to the west-center Tlahuac. The chinampas are surrounded
by towns of pre-Columbian origin such as Xochimilco, San Gregorio Atlapulco, San Luis
Tlaxialtemalco and San Pedro Tlahuac.
Fig.2-1 Location of study site
The study site is situated within an endorheic basin in the south of the basin of Mexico at
2,240 meters above mean sea level. As seen in fig.2-2, the study site is surrounded on the south
side by piedmont and hilly areas between 2,300 to 3,500 meters above mean sea level. The
climate in the study site varies from temperate sub-humid with fresh summers [Cb (w1) (w)]
2)
to dry semiarid-temperate with warm summers [BS1kw (w)] 2). The average annual temperature
ranges between 14°C to 16°C. The rainy season is in summer, with the most precipitation in July.
The annual precipitation goes from 800 mm to 600 mm 77).
21
The study site forms part of wetland remnants from ancient lakes in the basin of Mexico. It
features an alluvial plain of low permeability and phaeozem soil types (Phaeozem gleyic and Hh
phaeozem haplic) for agricultural purposes due to the presence of high amounts of organic
matters 77).
Figure 2-2, photo 1 illustrates that the study site’s periphery features urban, agricultural and
water settings, which sometimes appear to be interwoven with chinampas. Urban settings
include native towns and other urban developments that tend to expand into chinampas from the
south of Xochimilco and the west, north and east of Tlahuac 18).
The water settings feature canal areas toward the south of the study site, and a wetland,
which occupied some 661 ha in the center-north of Xochimilco (See fig.2-2, photo 2)51).
Fig. 2-2 Surroundings of study site
(Left side satellite photo from SEDEMA and PAOT 77); Right side photo 1 by David
Jimenez from ‘La casa de la Chinampa’; Right side photo 2 by Patricia Carrillo;
Right side photos 3 and 4 by the author)
22
Another important aspect for understanding the study site’s characteristics is the presence of
special designations for preserving chinampas. Some contents of special designations can be
seen in Table 2-1. First, in 1986, the Mexican authorities designated the chinampas as part of a
National Monument Zone to safeguard cultural properties in the south of Mexico City. In 1987,
UNESCO listed chinampas as a World Heritage Site because of its ecological and cultural
attributes. Afterwards, the Mexican authorities decreed the Natural Protected Area in 1992 to
conserve the biodiversity of chinampas and the wetland. The Ramsar convention recognized
chinampas as part of a wetland of international importance in 2004.
The multiplicity of designations denotes not only the ecological and heritage relevance that
nationally and internationally chinampas have, but also, it illustrates the complexity that
supposes the conservation of chinampas.
Table 2-1 Special designations for chinampas
Year
Designation
Site’s surface
Chinampa
surface
(×)
1986
National Monument Zone 1)
8,663 ha
(86.63 km2 )
1987
World Heritage Site 2)
7,534.17 ha (●)
2,440.16 ha (○)
1992
Protected Natural Area 3)
2,522.43 ha (◎)
1,178.02 ha
2004
Ramsar Site 4)
2,657.08 ha
1,312.57 ha
Reasons for the designation
Presence of 83 cultural properties, an
aqueduct and archeological
chinampas that witness the human
occupation across the lagoon shores
in the South of Mexico City.
Chinampa are the only remains of the
traditional land occupation system in
the ancient lagoon of the Basin of
Mexico, before the Spanish Conquest.
Habitat of plants and animals native
to the basin of Mexico. Site provides
environmental benefits to Mexico
City such as climate regulation and
aquifer recharge.
Wetland of international importance
for the conservation of biodiversity in
the basin of Mexico.
NOTES:
×Data not available; ●This data is as specified in the Master Plan for the World Heritage Site Xochimilco, Tlahuac
and Milpa Alta by UNESCO in 2006. As mentioned in the chapter 1, the site is one part of the World Heritage Site
Historic Center of Mexico City and Xochimilco. ○This surface includes the historic center of Mixquic village ◎This
surface is after the modification of the Natural Protected Area boundaries in 2006 (See chapter 3)
The sites’ official names are indicated as follows: 1) Historic Monument Zone in the boroughs Xochimilco, Tlahuac
and Milpa Alta, Federal District (Spanish: Zona de Monumentos Históricos en las delegaciones de Xochimilco,
Tláhuac y Milpa Alta, D.F.) ; 2) World Heritage Site, natural and cultural, in the boroughs Xochimilco, Tlahuac and
Milpa Alta (Spanish: Zona de Patrimonio Mundial Natural y Cultural de la Humanidad en las delegaciones de
Xochimilco, Tláhuac y Milpa Alta); 3) Natural Protected Area for Ecological Conservation “Ejidos de Xochimilco y
San Gregorio Atlapulco” (Spanish: Area Natural Protegida sujeta a proteccion ecologica “Ejidos de Xochimilco y San
Gregorio Atlapulco” ) , and 4) Lacustrine System “Ejidos de Xochimilco y San Gregorio Atlapulco” (Spanish: Sistema
lacustre “Ejidos de Xochimilco y San Gregorio Atlapulco” )
23
The study site boundaries were defined using the World Heritage Site as reference. As can
be distinguished in fig.2-3, the World Heritage site encompasses the widest expanses of
chinampas within the same spatial framework. The World Heritage Site includes within itself
the Natural Protected Area, the National Monument Zone and the Ramsar Site.
This study centers on chinampas because of the interest in ahuejotes, however, it is worthy
to say that the World Heritage Site involves many other sites that are somehow related to the
study site. According to UNESCO86), the World Heritage Site covers 7,000 ha and is divided in
four zones: 1) core zone under heritage preservation, 2) potential zone for heritage preservation,
3) buffer zone and 4) influence zone. The core zone includes sites considered to be key in the
manifestation of the Universal Outstanding Values in the World Heritage Site. Each site attaches
individual values that, as a whole, contribute to the universal outstanding value of the Heritage
Site86). The core zone includes, for example, chinampas, conventional agricultural areas, the
wetland, historic centers, and flower markets. Chinampas are the site where a chinampero, who
is the chinampa farmer, cultivates its crops; the flower markets are the sites where chinamperos
sell what they have cultivated in chinampas; and the historic centers, which accommodate many
historical monuments, buildings or other urban spaces, are the places where chinamperos and
their families spend daily life or celebrate their traditions.
Fig.2-3 Sites of special designations relating to chinampa
24
2.3. The characteristics of sources of information
The analysis of this study is supported by the processing of cartography, statistical data and
official reports. The description of the main information sources is shown below.
1. The Master Plan for the World Heritage Site of Xochimilco, Tlahuac and Milpa Alta
In 2006, as a part of the Master Plan for the World Heritage Site of Xochimilco, Tlahuac and
Milpa Alta, UNESCO generated a digital set of maps on the World Heritage Site for Geographic
Information System. Maps can be consulted in the annex of ‘Xochimilco: un proceso de gestion
participativa’ [Xochimilco: a process for participative management]
86)
. The maps include
information on bodies of water, vegetation, soil, agriculture, land uses, and on the zoning for the
World Heritage Site.
This study, using the information on vegetation, obtained the number of ahuejotes within the
study site through Arc Map 10 esri ©. The number of ahuejotes by each study unit can be seen
in the annex, table I. Additionally, this study used the information on bodies of water to identify
the canal network and lagoons in the study site.
2. The Census of Agriculture, Livestock and Forestry 2007
The Census provides raw data about the structure of the livestock, agriculture and forestry
sectors in Mexico. The census is produced by the National Institute of Statistics and Geography
of Mexico or INEGI (Spanish: Instituto Nacional de Estadistica y Geografia), and is available
online through the Livestock Statistic Information System (SCIGA by its name in Spanish
Sistema de Consulta de Información Geoestadística Agropecuaria) 43).
Technical details about the organization of the census and data processing were investigated
in the technical compendium43) of the ‘Livestock Statistic Information System (SCIGA), VIII
Census of Agriculture, Livestock and Forestry 2007’ [Spanish: Sistema de Consulta de
Informaction Geoestadistica Agropecuaria (SCIGA) VIII Censo Agricola, Ganadero y Forestal
2007]. The compendium is available online through http://gaia.inegi. org.mx/sciga/SCIGA.pdf.
The Census tabulates data at the level of farm holdings on economic activity, the number of
farmers, and the locality where farmer lives. The economic activities are referred to a key
number, which indicates the type of economic activity. According to the technical compendium,
the types of economic activities are classified into 3 groups: Agriculture, Livestock, and
Forestry. In the annex, table IV, it can be observed the number of farm holdings by each study
unit. The table IV also contains the number of agricultural holdings, livestock holdings and the
forestry holdings.
The census classifies each group of farm holdings into subgroups. The group of agriculture
activities, for instance, is classified into 5 subgroups: Grains and leguminous farming, Vegetable
25
farming, Fruit and tree nuts farming, Greenhouse, nursery and floriculture production farming,
and Other crop farming. Each subgroup is classified once more into classes, which indicate the
type of crops. The classes are classified once more into types. The compendium has a
description of each subgroup, class and type. With regard to the types, the compendium includes
a description on the type of plant and agricultural methods.
In the annex, tables V and VI, it can be observed the raw data that was gathered for this
study. It includes information on the types and numbers of farm holdings for each study unit.
3. Basic Statistics on Agriculture from SAGARPA
The Ministry of Agriculture, Livestock, Rural Development, Fishing and Nourishment or
SAGARPA (Spanish: Secretaria de Agricultura, Ganaderia, Desarrollo Rural, Pesca y
Alimentacion) has a database on the agriculture in Mexico City, which is possible to consult in
http://www.oeidrus-df.gob.mx/
71)
. The database provides information on the types of crops,
harvest surface (ha), sown surface (ha) and production of crops (ton).
4. The Census of Population and Dwelling 2010
The Census44) provides raw data about the characteristics of population and houses in
Mexico. The census is produced by the National Institute of Statistics and Geography of Mexico
or INEGI (Spanish: Instituto Nacional de Estadistica y Geografia), and is available to download
in http://www.inegi.org.mx/sistemas/consulta_resultados/ageb_urb2010.aspx?c=28111&s=est.
Technical details about the organization of census and data processing were investigated
in the technical manual ‘Census of Population and Dwelling 2010, Main Result by Ageb and
urban block’ [Spanish: Censo de Poblacion y Vivienda 2010, Principales resultados por ageb y
manzana urbana]. The manual45) is available online in http://www.inegi.org.mx/sistemas/
consulta_resultados/ageb_urb2010.aspx?c=28111&s=est.
The information on population offers data on number of inhabitant, age, fecundity,
migration, education levels, handicap population, economic characteristics, marriage status,
access to medical services, and religion. The information on dwelling includes the number of
houses, the number of rooms at house, types of construction materials, whether there is the
provision of public services such drain, electricity, and la presence of commodities such as
telephone, internet, television, radio and car.
In the annex, tables VII, it can be observed the raw data that was gathered for this study with
regard to the population and houses. It includes 3 aspects: population, number of houses and
number of houses with drain connection.
26
5. PAOT Technical reports
In 2012, the Environmental Attorney for the Federal District or PAOT (Spanish:
Procuraduria Ambiental y del Ordenamiento Territorial) elaborated a report
62)
on the lake and
wetlands in Xochimilco, using as a reference a study conducted by the Institute of Ecology A.C
(Spanish: Instituto de Ecologia A.C). The report offers a map and a description of the different
zones relating to the lake.
6. Atlas on the Conservation Land
In 2012, the Secretariat of Environment for the Federal District (Spanish: La Secretaria de
Medio Ambiente del Distrito Federal) prepared the Atlas of the Conservation Land in the
Federal District77). This document includes a series of maps on soil, vegetation, water, climate,
biodiversity, changes on land use, planning policies and irregular human settlements.
27
2.4 The study units
The study site was divided into a rural area and an urban area, using the National
Geographic Framework known as ageb
45)
(Spanish: Area geoestadistica basica) produced by
the National Institute of Statistics and Geography of Mexico or INEGI (Spanish: Instituto
Nacional de Estadistica y Geografia) as reference. An ageb is a census unit that gathers
information on some chinampa districts. There are two types of ageb: the rural one and the
urban one. Each type of ageb gathers different information and is referred to distinct chinampas
districts. The rural ageb contains information of livestock activities, whereas the urban ageb has
information about population and dwelling characteristics.
In the study site, there are both rural and urban agebs. As shown in table 2-2, the rural agebs
cover 1,435 ha of chinampas, whereas the urban agebs span 418 ha of chinampas. As can be
observed in fig. 2-4, the urban agebs and rural agebs are separated.
Table 2-2 Surface of study units in chinampas
Total of units
Type of unit
Study unit
Area (ha)
Rural unit
1 to 35
1,435.00
35
Urban unit
1U to 12U
418.00
12
1,853.00*
47
Totals
NOTE: * This surface includes an overlap of 32 ha. The surface of the study site is 1,821 ha.
As can be observed in fig. 2-5, study units 3 and 12u are overlaying. The overlay is due to
some differences in the year edition of census of Agriculture (2007) and Population (2010).
Within the rural area, there are two agebs (128-1 and 110-7), which contain 35 chinampa
sub-districts (or control areas) according to the National Census of Agriculture, Livestock and
Forestry 2007
43)
as can be observed in table 2-3. Each sub-district contains some chinampas,
canals and farm holdings, as illustrated by the study unit 3 in fig.2-4, photo 1. The study retook
the 35 chinampa sub-districts’ boundaries for the establishment of the study units, as indicated
in the cartography online for the Livestock Statistic Information System (SCIGA by its name in
Spanish Sistema de Consulta de Información Geoestadística Agropecuaria) 43). Once study units
(1 to 35) were traced in Arc Map 10 esri
(C)
, the next step was to calculate the surface of study
units (ha) (See fig.2-4 for the spatial reference about cartography). Afterwards, the size of farm
holdings for each study unit was calculated by dividing the surface of the study unit by the
number of farm holdings. The census provides the number of farm holdings but not the size of
each one. Table 2-3 contains the calculation results. It is distinguished that sizes of farm
holdings in each study unit are different. The sizes of farm holdings were utilized to calculate
the surface of each agricultural land use type, as will be shown in chapter four.
28
With regards to the urban area in chinampas, the National Census of Population and
Dwelling 201044) records 12 urban agebs. The study utilized those urban agebs to establish the
study units, as seen in table 2-4. In six of the study units (1u, 2u, 3u, 5u, 6u and 7u ), a part of
the ageb dropped outside the study site, so it was necessary to make an adjustment to possibly
meet the information of the agebs with the study units within the study site. The 2010 Census
provides information at the level of urban blocks, so the information of the six study units
coincides with the urban blocks that drop within the study site. As illustrated in fig.2-4, photo 1
with the study unit 9u, it is possible to observe some agricultural land use within the study units
in the urban area; but no information about it is available in Census. The cartography for urban
agebs was provided directly to the author by INEGI in digital format compatible with Arc Map
10 ©. (See fig.-2-4 for the spatial reference about cartography). Once cartography is obtained,
the size of study units was calculated and processed. In table 2-4, the surfaces of study units can
be seen.
29
Table-2-3 Study units for the rural area in chinampas
Fig.2-4 Distribution of study units and study units samples
30
Table 2-3 Features of study Units in the rural area in chinampas
Study
unit
State
Borough
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
The Federal District
Tlahuac
Tlahuac
Tlahuac
Tlahuac
Tlahuac
Tlahuac
Tlahuac
Tlahuac
Tlahuac
Tlahuac
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Xochimilco
Rural
Ageb_ID
110-7
110-7
110-7
110-7
110-7
110-7
110-7
110-7
110-7
110-7
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
128-1
Number of
farm
holdings per
study unit
181
43
41
30
36
15
6
27
10
12
25
39
24
17
31
19
16
18
22
21
26
18
30
30
25
20
101
24
21
13
8
47
68
43
43
Study Unit
surface (ha)
Size of farm
holding
(ha)
184.00
51.00
93.00
39.00
24.00
27.00
37.00
22.00
31.00
29.00
30.00
33.00
24.00
17.00
39.00
73.00
17.00
19.00
48.00
16.00
17.00
45.00
76.00
67.00
61.00
44.00
85.00
11.00
13.00
21.00
12.00
34.00
33.00
28.00
35.00
1.02
1.19
2.27
1.30
0.67
1.80
6.17
0.81
3.10
2.42
1.20
0.85
1.00
1.00
1.26
3.84
1.06
1.06
2.18
0.76
0.65
2.50
2.53
2.23
2.44
2.20
0.84
0.46
0.62
1.62
1.50
0.72
0.49
0.65
0.81
31
Table 2-4 Features of study Units in the urban area in chinampas
Study unit
State
Borough
Urban Ageb_ID
Area (ha)
1u
The Federal District
Tlahuac
344
2
2u
The Federal District
Tlahuac
1427
3
3u
The Federal District
Xochimilco
52
6
4u
The Federal District
Xochimilco
90
90
5u
The Federal District
Xochimilco
279
38
6u
The Federal District
Xochimilco
527
60
7u
The Federal District
Xochimilco
688
13
8u
The Federal District
Xochimilco
724
26
9u
The Federal District
Xochimilco
1099
42
10u
The Federal District
Xochimilco
1101
72
11u
The Federal District
Xochimilco
1489
12
12u (3*)
The Federal District
Tláhuac
1395, 1535
54
32
2.5 The organization of this thesis
This thesis is organized into six chapters as illustrated in fig.2-5. The contents of the
chapters are summarized below.
Chapter one: Background and literature review
The chapter focuses on reviewing relevant literature on chinampas through consultation of
indexed journals of computerized databases online and direct consultation of literature. The
chapter offers a point of reference for the discussion that takes place on the following chapters.
The chapter begins with a review to set the historical context of chinampas in the
pre-Columbian times. This is followed by an explanation of the characteristics of chinampas.
Afterwards, the significance of ahuejotes for chinampas was addressed. The chapter ends with
the argument for the need of this study.
Chapter two: Objective and methodology
The chapter includes the research foundations of this study: 1) objective, 2) study site, 3)
sources of information, 4) study units, and 5) organization of this study.
Chapter three: City planning framework for chinampas
The chapter analyses the city planning policies relating to chinampas through discussing the
conflicts among land use policies for the conservation of chinampas in the south of Mexico City.
Additionally, the analysis offers an overview about the social, environmental and demographic
aspects related to land use in rural settings.
Chapter four: Characterization and planning parameters in chinampas
The landscape characterization aims to discern the current conditions relating to ahuejotes
in chinampas. The analysis draws upon the information gathered during the desk study,
supported by the processing of cartography, statistical data and official reports. The analysis
focuses on the characteristics of ahuejotes, water resources, crop diversity, agricultural methods,
population density, housing density and drain cover. Based on the assessment of these
parameters, 5 landscape character conditions and 29 landscape character types were identified.
In the rural area, 3 landscape character conditions and 21 landscape character types were
identified. In the urban area, 2 landscape character conditions and 8 landscape character types
were recognized.
33
Chapter five: Management categories for the conservation of ahuejote
The chapter contains the management categories for the conservation of ahuejote in
chinampas, using the results of chapter 4 as reference. Here, the distribution of ahuejote from
the landscape character types is analyzed in order to identify the significance of ahuejotes in
chinampas. The objectives of management categories for conserving ahuejotes as a key
landscape element in chinampas are also described. The results and contributions of this study
are discussed in this chapter.
34
Fig.2-5 Research flow
––
35
CHAPTER THREE
CITY PLANING FRAMEWORK FOR CHINAMPAS
3.1 Features of City Land Use and Rural Planning in the regulation of chinampas
The study on the planning framework serves to gain an insight into the conflicts of land use
policy to conserve chinampas, which are the ahuejote’s surroundings, in the south of Mexico
City. The study breaks the analysis of current land use policies in two groups. The first
considers those policies designed to influence land use at the large scale and that, in the case of
this study, it would be used to clarify the aspects that intervene in the land conversion of
farmland in the urban fringe of Mexico City. The analysis includes the Overall Program of
Ecological Planning for the Federal District (2003) and the Overall Urban Development for the
Federal District (2010). The second policy group focuses on the current land use policies, at a
local scale, that regulate the land use zoning in chinampas. The review of the planning
framework includes the Urban Development Program for Xochimilco (2005), the Urban
Development Program for Tlahuac (2008), and the Management Program for the Natural
Protected Area (2006).
(1) Land-use policy at a large scale
Mexico City, formally known as the Federal District, belongs to the Metropolitan Zone of
the Valley of Mexico (Spanish: Zona Metropolitana del Valle de Mexico or ZMVM), which is an
urban agglomeration of 75 municipalities and boroughs in the Federal District (16 boroughs),
State of Mexico (58 municipalities) and State of Hidalgo (1 municipality). The Metropolitan
Zone spans about 7,815 km2 and its population is 18,396,677.
Mexico City occupies 1,485 km2. Its population is about 8.5 million44). The spatial structure
of Mexico City is comprised of urban and rural settings. Rural settings are a mosaic of
agricultural areas, woodland, water bodies, formally planned and informal residential areas as
well as native towns (Pre-Columbian villages). The rural settings belong to the conservation
land (Spanish: suelo de conservacion), which is a controlled area in the south of Mexico City3).
As can be seen in fig.3-1, the study site is located in the conservation land within Xochimilco
and Tlahuac.
The conservation land covers 87,297 ha75) or 58% of Mexico City. The conservation land
represents less than 1% of Mexico’s surface; however, it preserves 11% of Mexican
biodiversity75). The conservation land is the habitat of some 3,000 to 5,000 species of animals
and plants, for instance, the ahuejote, a tree native to Mexico City. Another example is the
ajolote
(Ambystoma mexicanum), which is an endemic salamander native to Xochimilco and
under special protection. Rana tlaloci, a species in danger of extinction30), is also an example.
36
The conservation land is also important due to the environmental service that it provides to
Mexico City, such as infiltration of rainwater and climate regulation. Furthermore, it is
culturally diverse. There are some 36 villages (Spanish: pueblos originarios) from
pre-Columbian origin49).
In 2009, there were seven types of land uses in the conservation land76): 1) woodland
(46,137 ha), 2) agricultural (17,729 ha), 3) human settlements (10,616 ha), 4) meadow (8,840
ha), 5) wetland (851,14 ha), 6) water bodies (476 ha) and 7) other (2,010 ha).
Fig. 3-1 Land use zoning in the Federal District
37
Table
3-1 General features of the conservation land
(ha) 1)
1990 1)
2000 1)
2010 3)
1990-2000
2000-2010
Population
Density
2010
(pop/ha)
Surface
Boroughs
Mean annual
growth rate (#)
Population
148,400
8,235,744
8,605,239
8,851,080
0.44
0.28
59.64
Benito Juarez
2,600
407,811
360,478
385,439
-1.23
0.67
148.25
Cuahutemoc
3,300
595,960
516,255
531,831
-1.43
0.30
161.16
Miguel
Hidalgo
4,600
406,868
352,640
372,889
-1.42
0.56
81.06
Venustiano
Carranza
3,400
519628
462,806
430,978
-1.15
-0.71
126.76
Mexico City
Conservation Land in the
Federal District
Surface
(ha)
(2000) 1)
% (*)
% (**)
88,442
×
59.60%
Central City
×
Boroughs with Conservation Land
Alvaro
Obregon
9,600
642,753
687,020
727,034
0.67
0.57
75.73
2,735
28.49
3.09
Cuajimalpa de
Morelos
7,000
119,669
151,222
186,391
2.37
2.11
26.63
6,593
94.19
7.45
Gustavo
Madero
8,800
1,268,068
1,235,542
1,185,772
-0.26
-0.41
134.75
1,238
14.07
1.40
Iztapalapa
11,400
1,490,499
1,773,343
1,815,786
1.75
0.24
159.28
1,218
10.68
1.38
Magdalena
Contreras
6,400
195,041
222,050
239,086
1.31
0.74
37.36
5,199
81.23
5.88
Milpa Alta
28,700
63,654
96,773
130,582
4.28
3.04
4.55
28,464
99.18
32.18
Tlahuac
8,600
206,700
302,790
360,265
3.89
1.75
41.89
6,405
74.48
7.24
Tlalpan
31,000
484,866
581,781
650,567
1.84
1.12
20.99
26,042
84.01
29.45
Xochimilco
11,900
271,151
369,787
415,007
3.15
1.16
34.87
10,548
88.64
11.93
Azcapotzalco
3,400
474,688
441,008
414,711
-0.73
-0.61
121.97
Coyoacan
5,400
640,066
640,423
620,416
0.01
-0.32
114.89
Iztacalco
2,300
448,322
411,321
384,326
-0.86
-0.68
167.10
A.
Other boroughs
×
NOTES:
Sources: 1) INEGI (2000) 41), 2) INEGI (2002) 42), 3) INEGI (2010) 44)
(*) indicates percentage respect to borough’s surface. (**) indicates percentage respect to Mexico City’s surface
(#) Mean annual growth rate calculated with the following formula: [(existing population/past population)1/n-1]*100. n=the number of
years in such period (INEGI, retrieved November 20th, 2013 from https://www.coveg.gob.mx/seiisv/ modulos/secciones/indicadores/
indicadores/ Indicador %204.pdf)
Regarding the population in the conservation land, table 3-1 indicates positive rates of growth
in the last ten years (2000-2010) in the boroughs with conservation land, except for Gustavo A
Madero. In the case of Xochimilco and Tlahuac, where the study site is located, the annual
38
growth rate is almost five times the Federal District. Although the population density in
Xochimilco and Tlahuac remained below the average in the Federal District in 2010, the surface
suitable for build-up is so far less. The surface of conservation land is more than 74% and 84%
for Tlahuac and Xochimilco, respectively.
The growth of population parallels urban agglomeration. Urban agglomeration reflects the
demands of housing and the expansion of human settlements. As can be seen in table 3-2, the
number of housing in Tlahuac increased from 39,367 in 1990 to 90,275 in 2010. Meanwhile, in
Xochimilco, the number of houses changed from 53,051 in 1990 to 101,124 in 2010. Urban
expansion takes varying forms, such as informal settlements. It inevitably covers some
agricultural land or ecological areas. Official reports76) indicate that in 2011, there were 858
informal settlements within 858 ha in the conservation land. 309 informal settlements (570.20
ha) were located in Xochimilco, and 93 informal settlements (410.96 ha) in Tlahuac.
Table 3-2 Distribution of houses in boroughs Xochimilco and Tlahuac
Borough
Surface
(ha)
House density
Number of houses
1990
2000
2010
1,799,410
2,132,413
2,388,534
(Houses/surface)
Houses mean growth rates
1990-2000
2000-2010
16.09
1.71
1.14
69,564
90,275
10.49
5.86
2.64
82,078
101,124
8.49
4.46
2.11
1. Number of houses
Mexico City
Tlahuac
Xochimilco
148,400
8,600
11,900
39,367
53,051
In parallel to urban expansion and population growth, the labor force changes. The share of
agriculture in the labor force declined in Mexico City. In 2000, 0.6 % of the population of
Mexico City belonged to the primary sector of labor force. In the context of the study site, the
decline in the primary sector decreased from 19.2 % of the population in 1970 to just 2.1 % in
2000 in Tlahuac. In Xochimilco, 3.1 % of labor force was dedicated to activities in the primary
sector in 2000 compared with the 15.6 % in 1970.
The control of urban expansion on the conservation land, in most instances, has little
effectiveness over land-use conversion from agricultural to non-agricultural land. As mentioned
in chapter 1, section 1, diverse studies have demonstrated that the planning regulations have not
halted urban expansion. The little effectiveness of land regulation starts with conflicts among
land use policies at regional and site scales.
Mexico City’s land use policy essentially works through three distinct ways: 1) Growth
boundary, 2) Land use zoning, and 3) Limitation on the provision of basic infrastructure.
1) Growth boundary
The growth boundary or, as called on the planning documents, the “line of Conservation
Land” (Spanish: Linea del suelo de Conservacion) 31) is the legal, but not de facto limit. Beyond
39
it, urban expansion is not allowed. As seen in fig. 3.1, the growth boundary divides Mexico City
into the conservation land and the urban land. It is thought of as the primary planning mean to
control urban expansion over the conservation land. The growth boundary dates from 198772).
2) Land use zoning.
Land use zoning in Mexico City is founded on a double approach to the management of
rural settings, and this includes urban and ecological planning. The ecological planning in
Mexico appeared in the 1970s. With the designation of the Law of Human Settlements (1976)
(Spanish: Ley General de Asentameintos Humanos), the national planning framework
introduced the ‘ecological plans’ into the urban planning58). The “ecological plans” emerged as
an initiative to mitigate the urban effects of cities on the environment. With the Law on
Environmental Protection (Spanish: Ley General de Protecion al Ambiente) in 1982 and its
reforms in 1984, the ecological planning emerged as the policy to organize ecologically the
natural territory and to ensure the protection of natural resources.
Since the introduction to ecological planning, the Mexican planning framework was
evolving toward a sectorial orientation in the management of land. Ecological planning
approaches ecology and environment, whereas urban planning is in charge of urban
development and human settlements.
In Mexico City, the ecological planning was introduced in the Law on Environment in 2000
(Spanish: Ley del Medio Ambiente)27). The Law states that the ecological planning is a
mandatory policy for the management of the conservation land through establishing zoning and
regulations on rural activities and conservation of natural resources. The ecological planning is
essentially based on the study of the potentialities of land use, which is known as Environmental
Management Units (UGAS by its name in Spanish, Unidades de Gestion Ambiental)77). The
Secretariat of the Environment (SEDEMA by its name in Spanish: Secretaria del Medio
Ambiente) is in charge of elaborating the Program for Ecological Planning in the Federal
District (Spanish: Programa General de Ordenamiento Ecologico del Distrito Federal).
In parallel, the Secretary of Urban Development and Housing (SEDUVI by its name in
Spanish: Secretaria del Desarrollo Urbano y Vivienda) assumes the responsibility for the urban
policy and the elaboration of the Overall Urban Development Program for the Federal District
(Spanish: Programa General de Desarrollo Urbano del Distrito Federal). The Urban
Development Program also assigns land use zoning to control urban development in rural
settings, retaking the criteria from the Program of Ecological Planning.
40
Table
3-3 Contents of land use plans at regional scale relating to chinampa
Plans at regional scale
Comparable
Urban approach
attributes
Name
Overall Urban Development Program for
the Federal District 29)
Year launched
2003
Specific zoning
Areas of rural and agro-industrial
categories for
production
chinamperia
These areas are intended for agriculture,
livestock, fishery, forestry, tourism, and
agro-industrial production.
Ecological approach
Program for Ecological Planning 27)
2000
Special agricultural and livestock ecological zones
These zones comprise the chinampa zones and
wetland in Tlahuac and Xochimilco. Due to their
vulnerability, these areas are subject of special
regulation to conserve their ecological, traditional and
cultural features.
The result of the current land-use policy is that the rural settings have two types of land-use
zoning, urban and rural, overlapping each other. In the case of the study area, the land use for
chinampas is assigned to agriculture purposes, as shown in table-3-3. Each regional plan
emphasizes different aspects of land-use zoning. The urban plan addresses the land-use zoning
in more general terms, whereas the ecological plans focus on regulating site conditions carefully.
This produces ambiguities on objectives, norms and procedures between urban and rural
land-use policies 6, 58).
3) Limitations on the provision of basic infrastructure.
In the conservation land, the aim is to halt urbanization. A key strategy is to discourage the
settlement of new social groups through forbidding the introduction of basic public services,
such as drainage or electricity supply.
The application of this policy brings the segregation of low-income groups in informal
settlements in the conservation land.
(2) Land use policy at a site scale
The land use policy at a site scale for chinampas consisted of urban and ecological plans. As
can be seen in table 3-4, land use zoning follows double zoning approach to the management of
chinampas similar to the city framework. The result of the current land-use policy at sites is the
presence of various types of land use zoning, urban and rural, overlapping each other in
chinampas. Each type of plan emphasizes different aspects of land-use zoning. Urban plans state
generalized visions on chinampas within distinct urban development frameworks. On the other
hand, ecological plans focus on chinampas through the land use known as the natural protected
area, which is the strictest category of land use in ecological planning.
41
Table 3-4 Contents of land use plans at site scale relating to chinampa
Programs at site scale
Comparable
Urban plans
attributes
Name
Urban Development Plan
Urban Development Plan for
for Xochimilco 32)
Tlahuac 33)
Vision
To achieve a
Consolidate the area of
comprehensive land use
Tlahuac as a transition
that contributes towards
territory between rural and
regional integration and
urban land, within a
the sustainable use of
metropolitan level.
human and natural
resources in accordance to
local customs.
Year launched
2005
2008
Main focus areas
Urban land, conservation
Urban land, conservation
land, cultural heritage,
land, agriculture, livestock,
protected natural area,
forest, aquaculture, wildlife,
informal settlements,
tourism, infrastructure and
housing, transportation,
public services, informal
public services, security
settlements and metropolitan
and outdoor publicity.
zone.
Specific zoning
1. Areas under
1. Areas of ecological use
categories for
agro-industrial use
under restoration.
chinamperia
Areas intend to
Zone for ecological
agriculture, livestock,
restoration due to
fishery, forestry, tourism,
unsustainable uses of land
and agro-industrial
2. Areas of rural and
production.
agro-industrial production
Areas intended to agriculture,
livestock, fishery, forestry,
tourism, and agro-industrial
production.
3. Rural facilities
Ecological plans
Program for the Protected
Natural Area in Xochimilco30)
to achieve a comprehensive
management of the wetland's
natural resources that
contributes to the conservation
of the ecosystem and to
promote and reinvigorate the
traditional techniques of
chinampa agriculture.
2006
Water, natural resources,
biodiversity, cultural landscape,
restoration, agriculture,
recreation, monitoring,
community participation,
inter-departmental coordination.
1. Chinampa and rain-fed
agriculture zone
Agriculture areas under
ecological, productive and
landscape restoration and
essential for the conservation of
traditional chinampa
agriculture, vital in order to
protect cultural richness
2. Public use zone
Areas ecologically deteriorated
by human settlements and under
special management regime
according to the natural
protected area program.
As shown in table 3-5, chinampas have different levels of regulation, which appear to form
an overregulation framework over them6). Notwithstanding the land use regulations, chinampas
have been overwhelmed by urban pressure. According to a report by the Environmental
Attorney for the Federal District 63) (PAOT by its name in Spanish: Procuraduria Ambiental y el
Ordenamiento Teritorial), there were 44 informal settlements (92.77 ha) in chinampas for 2010.
Proportionally, the surface that was covered by informal settlements is wider in Xochimilco (34
human settlements, 68.13 ha) than Tlahuac (10 human settlements, 24.64 ha).
42
Table 3-5 Main Features of land use plans relating to chinampa
1. Urban plans
2005 Program of urban development
●
2008
●
Program of urban development
2010
Overall Program of Urban
Development
2. Ecological plans
2000 Overall Program of Ecological
Planning
2006 Program of Natural Area
Boroughs
Tlahuac
Xochimilco
Land use
relating to
chinampas
Site
Plan’s name
Borough
Year
Regional
Plan scale
●
●
●
●
●
●
●
●
●
●
Agro-industria
l
Ecological;
agro-industrial
Rural and
agro-industrial
Agricultural
Natural Area
Agricultural/
Public use
●indicates scale and sphere of application for plans
Regarding the forms of urbanization in chinampas, studies report the occupation of
chinampa starts little by little, with the appearance of “ant-like” sprawl (Spanish: mancha
hormiga), which is a pattern of small but creepy occupation on chinampas91) 92). This ‘ant- like’
sprawl entails constant monitoring by the authorities on the establishment of new human
settlements.
The management of informal settlements touches on sensitive issues that involve human
rights. There is the need of protecting chinampas, but also the demand for housing from many
people, who legally or illegally, take possession of chinampas. In 2012, the Commission of
Human Rights in the Federal District17) (CDHDF by its name in Spanish Comision de Derechos
Humanos del Distrito Federal) emitted the recommendation 19/2012 to fix the violation on
human rights of owners and dwellers in chinampas (CDHDF, 2012). On the basis of citizen
denunciation, the Commission argued that the presence of informal settlements violated the
right to have a healthy environment, decent housing, and the enjoyment of the heritage of
chinampas. The Commission urged the city authorities to take measures promptly and regain
chinampas by giving an appropriate solution to the presence of informal settlements and
relocating them. Indeed, the relocation of informal settlements from chinampas involves dealing
with complex dynamics.
43
CHAPTER FOUR
CHARACTERIZATION
OF
THE
EXISTING
CONDITIONS
FOR
AHUEJOTES
IN
CHINAMPAS
The landscape characterization is to discern the conditions currently relating to ahuejotes in
chinampas. The analysis draws upon the information gathered during the desk study, supported
by the processing of cartography, statistical data and official reports. Initially, the analysis
focuses on the characteristics of the ahuejote and water as two key landscape elements of the
chinampa landscape structure. Next, the land use types were assessed according to the rural or
urban context in chinampas. Finally, landscape character conditions and landscape character
types were identified. The landscape typology constitutes the basis for the establishment of
management categories in the next chapter.
4.1 Assessment of the key landscape elements in chinampas
(1) The density of ahuejote planting in chinampas
The existing ahuejote planting was assessed through the estimation of tree density of
ahuejotes per hectare. The coefficient of tree density for each study unit was calculated using
data and cartography on ahuejote produced by UNESCO in 200686). Data was processed in Arc
Map 10 esri © and Excel Microsoft ©. The coefficients of tree density were distributed into four
categories: high, medium, low and none. Afterwards, the study units were characterized
according to the tree density categories.
As shown in table 4-1, the results indicate that tree density rated 11.77 ahuejotes per ha
(21,447 ahuejotes ÷1,821 ha) in chinampas (See the annex, table I, for the raw data). The
study units that feature high tree density cover 534 ha (17 units) and represent 29.34 % of
chinampas. Comparatively, the study units that feature low density span 1,051 ha (19 units) or
57.71 % of chinampas, indicating that there are many chinampas where ahuejote seems to be
absent.
Fig. 4-1 shows that high density study units concentrate into two blocks to the west and the
center-south of the study site. Comparatively, low density study units can be mainly seen toward
the center and northeast of the study site. The distribution of ahuejote between the rural and
urban areas indicates that the widest expanses of high density units (330 ha, 14 units) are within
the rural area; however, the presence of high density units seems proportionally more important
in the urban area, where it represents 56.10% (204 ha÷364) of chinampas. The proportion of
low density units of ahuejote is wider in the rural area in comparison with the urban area.
44
Table 4-1 Distribution of ahuejote densities in chinampas
Categories
Area (ha)
%
(*)
Number
of
ahuejotes
Ahuejote density
(ahuejotes per
hectare)
Study units
Total of
study
units
Rural area
High
534
29.34
14,459
27.07
17
Medium
210
11.53
2,690
12.80
8,11,12,13,14,17,18,19,20,21,28
,29,34,35, 4U,9U,10U
5,9,10,15,22,30, 1U,3U,7U
Low
1,051
57.71
4,293
4.08
19
None
26
1.42
0
0.00
1,2,3,4,6,7,16,23,24,25,26,27,3
1,32,33, 2U,5U,6U,11U
8U
Total
1,821 (#)
100
21,447
11.77
9
1
46 (#)
NOTES:
* % calculated respect to 1,821 ha.
# This surface is slightly different from the one shown in table 2-2. Here, the overlay surface of study units 3 and
12u, which is of 32ha, is not taken into account. Here, study unit 12u does not appear, but it will be retaken later in the
assessment of urban area in chinampas. For study unit 12u, the data for study unit 3 will be used as reference only with
regards to ahuejote density and water units.
Categories values: High >17.08 ahuejote per hectare, Medium >8.33 <=17.08 ahuejote per hectare, Low>=0.23
<=8.33 ahuejote per hectare, and None ahuejote=0.00.
The values of each category were calculated using percentiles. Percentile 0= 0.23; Percentile 1=57.16
See table-I in the annex for consulting raw data.
Fig.4-1. Distribution of ahuejote in chinampas
45
(2) Water resources and water units in chinampas
Ahuejotes are planted in a line along the edge of chinampas, as illustrated in photo A, fig.
4-2. The edge of the chinampa acts as an interface between the chinampa plot and canals. The
ahuejote provides a shadow to crops and, at the same time, avoids the erosion of the edge. The
canals that surround chinampas can be seen to form axes that appear to organize chinampas in a
washboard. The planting of ahuejotes follows the organization of chinampas simulating a forest.
In chinampas, there are some 189 km of canals, which are distributed into three districts:
west, center and east, as illustrated in fig. 4-2. Some of the main canals include Canal de Chalco
and Canal Revolucion to the North, canal Apatlaco to the south, Canal del Bordo and Canal del
Cuemanco to the west, and Canal Caltongo to the east. Canals can be seen with lagoons, which
help to regulate water speed and control floods.
In terms of property, there are two types of canals: acalotes and apantles. Acalotes are
public canals that work as primary arteries of communication across chinampas. Apantles are
private canals that distribute and circulate water among chinampas. The ahuejote grows in the
edges of both types of canals, as can be observed in photos A and B, fig. 4-2. In comparison to
acalotes, apantles are narrower canals.
As can be seen in photo I, fig. 4-2, there is a lake in the center-north of the study site. The
lake occupies 661 ha of land that was used for conventional agriculture (rain-fed). The lake is a
new body of water that appeared on a zone affected by land subsidence at the end of 1980s51).
The lake expands and reduces chinampas, altering the canal network and provoking floods and
drought through the years. As illustrated in the map on fig. 4-2, the lake essentially consisted of
three zones63). The first one is the lake zone itself. Its size and profoundness tends to increase as
long as land subsidence occurred. The lake zone features floating species of Eichhornia
crassipes and sub-aquatic species of Typha spp. and Schoenoplectus americanus. The second
zone is the wetland, which is the area surrounding the lake. The wetland is the shallow habitat
of floating plants such as Eichhornia crassipes and sub-aquatic plants such Typha spp. and
Schoenoplectus americanus. The third zone is the flooded area. Although the expansion of the
lake affects chinampas, today, it is the habitat for many species of animals and plants51).
During the rainy season, flood risks increased affecting crops in chinampas due to the lake.
As a response to such problems, chinamperos often leveled the chinampas to protect their crops
by introducing excavation wastes. For instance, the city authorities75) reported the introduction
of more than 258,000 m3 of excavation wastes to level chinampas in some chinampa districts
from 2002 and 2012. The practice of leveling could be considered as intrinsic to keep a
functional chinampa, however, they occur without any supervision from authorities. As seen in
photo C, fig 4-2, leveling chinampas can mean a change in soil properties and ahuejotes.
46
Fig.4-2 Water resources across chinampas
Photos A by the author, photo B and C by David Jimenez from ‘La casa de la chinampa’
47
The operation of water in canals and lagoons often struggles due to the presence of land
subsidence. Land subsidence is reported to be a consequence of overexploitation of aquifers in
Mexico City63), 70). A report estimates that water exploitation is 1.73 times the local natural
recharging rate in Mexico City 59. Official reports indicate that 32.16 m3/s of drinking water is
needed to cover eight million citizen69). To supply such demand, in 2011, the city authorities
obtained 14.87 m3/s of water (46.24%) within the City. 8.11 m3/s were extracted directly from
the aquifer in the south of Mexico City. In proportion, such 8.11 m3/s is equal to the volume of
water that is pulled out from the Cutzamala System, which provides some 9.43 m3/s. The
Cutzamala System is 124 km from the Mexico City, in the states of Mexico and Michoacán,
therefore, the cost of transportation and supply implies high energy consumption in comparison
to the water that is extracted within the city.
The water that is extracted from the south of Mexico City comes from the aquifer in
Xochimilco and Tlahuac the most. As illustrated in fig. 4-3, water extraction takes place mainly
in Xochimilco, where it annually oscillates around 3.00 m3/s. The number of wells has increased
progressively, from 8 wells in the 1950s to 104 in the 2010s, as seen in fig.4-3. In 1940, official
reports indicated problems in drainage infrastructure and buildings as a result of land subsidence
in the center of Mexico City70). To control the rhythm of land subsidence, authorities decided to
reduce groundwater extraction in the city’s center and increased it in the south of Mexico City.
Fig.4-3 Volume of groundwater extracted in Xochimilco and Tlahuac
Land subsidence hinders water circulation across canals. If canal slopes change, the
regimens of water circulation is modified and the water table losses its balance54). A study
conducted by Gonzalez et al.36) from 2005 to 2006 shows the research of the conditions of water
levels in a chinampa district to the south of the study site. They found wide differences in the
water table along canals. The depth from the water table to bottom of the canals ranged between
48
fifty centimeters and three meters, whereas the distance between the water line and the
chinampa surface varied between ten centimeters and five and half meters. The variation of
water levels is reflected in the water available for ahuejote planting, as illustrated in photos 1
and 2, fig. 4-4. Furthermore, it hinders navigation across canals and it often provides difficulties
on the transportation of merchandises to chinamperos.
Fig.4-4 Ahuejote and the water levels in chinampas
Photo 1 and 2 by David Jimenez from ‘La casa de la chinampa’
In order to control water levels in chinampas, canals and lagoons operate under a scheme of
water discharges, barriers and lock gates. The west and center districts receive treatment water
discharges in the south, while barriers along canals create small sections to contain water. The
water discharges usually are opened to maintain water levels and keep canals suitable for
navigation, unless the water table exceeds safety levels. If chinampas are at flood risk, lock
gates are opened, and the water is released to canal Chalco. Canal Chalco is a regional canal that
conducts water to the city drainage system. In the east district, canal Revolucion receives
treatment water, which is conducted through a tube line to the lagoon ‘Laguna de los Reyes
Aztecas’. In ‘Laguna de los Reyes Aztecas’, water is distributed to chinampas through canals.
When there is a risk of flood, water excess is withdrawn from canal de Chalco and is lead to the
city drainage system. In the east district, there is also a water section that is supplied through an
underground irrigation system.
Considering the aspect mentioned above, water conditions in chinampas were assessed
through the presence of canal network. The canal network is an important characteristic of
organization that reflects the level of control and distribution of water across chinampas. Canal
network is fundamental in the delimitation of chinampa plot and provision of water for crops.
The permanency of canal network is essential to keep tree covers and to enhance the spatial
structure of chinampas.
49
Water was assessed through the use of cartography and reports prepared by UNESCO86) and
PAOT62). As a result, five water features were identified: 1) canal network, 2) lake, 3) wetland,
4) flooded area, and 5) irrigation mechanized systems. Cartography was processed in Arc Map
10 esri © and, as a result, nine water types were established, as can be observed in table 4-2.
Next, study units were characterized according to water types.
The results in table 4-2 and fig. 4-5 show the presence of water type I the most (941 ha, 32
units), which equals 51.67% of chinampas where there are some canal networks. What follows
are water types II to VII (451 ha, 7 units), which cover 24.77 % of chinampas, which feature
canal networks that coexist with other water conditions derived from the presence of the lake
and the wetland. Water type VIII, which covers 6.31% of chinampas (115 ha, 1 unit), contains a
mechanized irrigation system, but there is an absence of canal networks. Finally, in water type
IX (314 ha, 6 unit), which is 17.25 % of chinampas, the absence of canal networks is observed.
50
Table 4-2 Features of water unit types in chinampas
Other
Irrigation
system
Flooded
area
Wetland
Lake
Water
types
Canals
Water conditions
Area
(ha)
Total of
% (*)
941
I
units
5,6,7,8,9,10, 1,12,13,14,15,17,
51.67
●
Study units
18,19,20,21,28,29,30,31,32,33,34,35,
32
2U,3U,4U,5U,6U,7U,9U,10U
II
●
III
●
IV
●
●
V
●
●
VI
●
VII
●
85
4.66
27
1
45
2.47
22
1
61
3.34
25
1
●
73
4.00
16
1
●
●
44
2.41
26
1
●
●
143
7.85
23,24
2
115
6.33
3
1
●
314
17.27
1,2,4,1U,8U,11U
6
Totals
1,821(#)
100
●
●
●
●
VIII
●
IX
46(#)
NOTES:
% calculated respect to 1,821 ha
# This surface is slightly different from the one shown in table 2-2. Here, the overlay surface of study units 3 and 12u, which is
of 32ha, is not taken into account. Here, study unit 12u does not appear, but it will be retaken later in the assessment of urban area
in chinampas. For study unit 12u, the data for study unit 3 will be used as reference only with regards to ahuejote density and
water units.
See tables II and III in the annex for consulting each study unit’s data
Fig. 4-5 Distribution of water units types in chinampas
51
4.2 Assessment of existing conditions for ahuejotes in the rural area in chinampas
(1) The characteristics of land use types in the rural area in chinampas
The assessment of land use is an important step toward the characterization of existing
conditions of ahuejote planting in the rural area in chinampas. The analysis of land use is
fundamental to understand the rural aspects that will influence the management of ahuejote
planting in the future. The analysis of land use is based on a statistical study of rural data from
the Census of Agriculture and Livestock 200743) produced by the INEGI. The data distinguishes
the characteristics of farm holdings within study units by types of farm activity, crops diversity,
agricultural methods and number of chinamperos.
To calculate the surface of land uses, the first step was to classify the farm holdings into two
classes: 1) agricultural and 2) livestock. The second step was to divide the agricultural farm
holdings into two sub-classes. One sub-class includes five types of farm holdings according to
crops diversity: 1) grains, 2) vegetables, 3) fruit tree, 4) flowers and 5) other crops. Another
sub-class contains two types of farm holdings based on the characteristics of agricultural
methods: 1) open field agriculture and 2) greenhouse agriculture. The third step consisted of
preparing layers for agricultural land uses using the information from the second step. The
surface of agricultural land uses was calculated for each study unit, utilizing the next formula:
number of farm holding by each land use type×the average size of farm holdings. The
distribution of land use types is shown in table 4-3. Additionally, the number of farmers by each
land use class was calculated.
The rural area in chinampas can be described as a combination of agricultural and livestock
land uses. Its surface is 1,435 ha. The agricultural land use in chinampas covers 81% (1,169.16
ha). Agriculture continues being the main farm activity in chinampas but it coexists with
livestock activities (265.84 ha). Within the agricultural land use, agricultural diversity
encompasses three main land use types for cultivation: grains (45%, 521.94 ha), vegetables
(34.55%, 403.82 ha) and flowers (19%, 224.41 ha). According to the agriculture methods, the
agricultural land use that is dedicated to open field agriculture spans 83% of chinampas (970.35
ha), whereas the land use for greenhouse agriculture covers 198.81 ha.
With regards to the number of farmers, there are 5,358 persons that are engaged in farm
activities. 4,422 persons (82.5 %) are dedicated to agriculture whereas 936 (17.5%) conduct
livestock activities.
52
Table 4-3 Distribution of land uses in chinampa
Surface
(ha)
Number of
holdings
Size of holdings in
average (ha)
Surface (%)
1,150
1.25
100%
Farmers
1) Rural area in chinampas
1,435.00
2) Agricultural land use of the rural area in chinampas
Agriculture
1,169.16
968
Chinamperos
1.20
81%
4,422
Livestock
farmers
1.46
19%
936
3) Livestock land use of the rural area in chinampas
Livestock
265.84
182
5,358
4) Diversity of plants cultivated in the agricultural land use area
Grains
521.94
422
1.23
45%
Vegetables
403.82
344
1.17
34.55%
Fruit trees
12.17
8
1.52
1%
Flowers
224.41
191
1.17
19%
6.83
3
2.27
0.50%
Other plants
5) Agriculture methods in the agricultural land use area
Open field
970.35
796
1.21
83%
Greenhouses
198.81
172
1.15
17%
53
(2) The characteristics of chinampero density
The chinampero density measures the concentration of people exclusively devoted to
agriculture per hectare in the agricultural area in chinampas. The ahuejote is a tree that grows on
land owned by chinamperos, therefore, this parameter is basic to explore the potential of people
that could be involved in the attention and care of ahuejote planting.
The chinampero density was investigated using the data from the General Census of
Agriculture and Livestock 200743). The coefficient of chinampero density was calculated in
Excel Microsoft © and classified into three categories: high, medium and low. As shown in
table 4-4, the study units were characterized on the basis of three categories as follows: high
(560 ha, 14 units), medium (248 ha, 7 units), and low (627 ha, 14 units). The distribution of
chinampero density was mapped in Arc Map 10 esri © as illustrated in fig. 4-6.
The results show that farmer density in chinampas is 3.78 people per ha in average. Table
4-4 notes that the number of study units of high and low densities rates is the same (14 study
units by each density category). However, the study units of high density covers only 39.04% of
chinampas (560 ha) in the study site. A cover of such size indicates that the intervention of
chinamperos in the care of ahuejote planting appears to remain low in many chinampas.
Fig. 4-6 illustrates that the higher concentrations of chinamperos can be located in five
blocks across the study site. The first block can be seen toward the Southwest, near the urban
area. The second block is observed in the South-center, on the opposite side of the lake and next
to the urban area. The third block is toward the southeast, near the lake and next to the urban
area. In the east of the study site, the fourth and fifth blocks are found. The fourth block is
toward the North, next to the urban areas. The fifth block is in the Center, amongst chinampas.
54
Table 4-4 Categories of chinampero density
Category
Surface
(ha)
% (*)
Agricultural
surface (ha)
Chinampero
Agricultural
density
(chinampero
per hectare)
Study units
Total
of units
High
560
39.03
491.14
2,848
5.79
1,4,5,8,18,20,21,
27, 28,29,32,33,
34,35
14
Medium
248
17.28
193.14
700
3.62
2,12,13,14,15,17,
24
7
Low
627
43.69
492.88
874
1.77
3,6,7,9,10,11,16,
19,22,23,25,26,
30,31
14
1,435
100
1,169
4,422
3.78
35
NOTES:
Categories values: High >4.35 chinampero per hectare, Middle >3.02 <=4.35 chinampero per hectare, Low>0.51
<=3.02 chinampero per hectare. Values based on the application of percentiles. Percentile 0=0.51, Percentile
1=9.39
*% calculated respect to the rural area in chinampas (1,435 ha)
See table V in the annex for consulting raw data
Fig. 4-6 Distribution of chinampero densities
55
(3) The characteristics of crop diversity types
Crop diversity assesses the variety of different crops in chinampas. Crop diversity explores
the functional use or disuse of ahuejotes in chinampa agriculture. The use of ahuejotes in
chinampa agriculture is essential for conserving tree planting. A variety of crops were
investigated using the data from the Census of agriculture and Livestock 200743). A variety of
plants for each crop type were studied, supported by a literature review and technical reports.
Study units were characterized based on the spatial dominancy of some groups of crops
within the study unit. A group of crop was considered to be dominant when it covered more than
51% of the surface area within the study unit. As shown in the table 4-5, four crop diversity
types were established: grain type, vegetable type, flower type and mixed type, which includes
two or three of the previous types. Study units were characterized according to the crop
diversity types.
The results show that the study units of grain type cover 606 ha (13 units). These are
followed by the study units of mixed type, which cover 401 ha (12 units). Next, the study units
of vegetable type cover 331 ha (8 units). Finally, the study units of flower type covers 97 ha (2
units).
Regarding the distribution of study units, fig. 4-7 illustrates that the study units in the east
are basically dedicated to grain cultivation. In the west, the study units feature mixed cultivation
combined with grain cultivation. In the center, there are two blocks of crop diversity. The one on
the east is devoted to flower cultivation, while the center and the south sides perform vegetable
cultivation.
The diversity of plants within each crop group suggests higher diversity within the flower
group. Table 4-6 lists some of the plants currently in cultivation in chinampas. As seen in the
table, some of the plants, for instance, maize, come from pre-Columbian times or just after the
Spanish conquest.
56
Table 4-5 Characteristics of crop diversity types
Crop
Crop types
Grain
Vegetable
Flower
Mixed
Grain surface (ha)
374.23
13.86
2.52
131.32
% (*)
80.00
4.00
2.83
40.74
Vegetable surface (ha)
60.02
232.91
13.47
97.42
% (*)
13.00
81.00
14.96
30.22
Fruit surface (ha)
11.12
0.00
0.00
1.06
% (*)
2.00
0.00
0.00
0.35
Flower surface (ha)
24.41
39.86
73.99
86.16
% (*)
5.00
12.83
82.21
26.73
Other crop surface (ha)
0.00
0.49
0.00
6.34
% (*)
0.00
0.17
0.00
1.96
469.77
287.12
89.98
322.29
Agricultural surface
Study unit
1,2,3,4,5,6,7,8,9,14,19, 10,24,25,26,32,33,
20,21
34,35,
27,31
Totals
521.94
403.82
12.17
224.41
6.83
1,169.16
11,12,13,15,16,17,18,22,
23,28,29,30
Total of units
13
8
2
12
Unit surface (ha)
606
331
97
401
1,435
42.25
23.06
6.75
27.94
100
% (**)
NOTE:
*Percentage calculated respect to the agricultural surface (1,169 ha)
** Percentage calculated respect to the rural surface in chinampa (1,435 ha)
See table VI in the annex for consulting raw data
Fig.4-7 Distribution of crop diversity
57
Table 4-6 Variety of crops in chinampas
Type of crops
Crops cultivated in chinampas in pre-Columbian
times or introduced with the Spanish conquest
Squash 4), beans4), 5), tomato2),5)
chili 2), 5), romerito 5) ,quelites 5)
vegetable pear 5), gourd5), radish 2), onion 2),
spinach 2), lettuce 2), beetroot2), cauliflower2),
turnip 2), medicinal plants5)
Some crops currently cultivated in chinampas
Flowers
Cempoalxochitl 5)
Grains
Chia 4), 5), amaranth 4), Maize4), 5), 2)
Geranium 1), 2), poinsettia 1), 2), rose1) 2),
wallflowers 1), 2), 3), carnation 2) , wormwood
3)
, begonia 3). impatiens 3), chrysanthemum 3),
sunflower 3), petunia 3)
Maize 2)
Vegetables
celery 1), 3), chard 1), 3), lettuce1), 3), spinach 1),
3)
, broccoli 1), cauliflower 1)
radish1), 3), squash (zucchini) 1), purslane1), 3),
romerito1), 3), coriander 3), mint 3)
References: 1) Sagarpa,2013 63) ; 2) Lopez, a., et al, 2006 47); 3) Merlin-Uribe, Y., 200943) ; 4) Jimez-Osorio, J.J. and
Gonzalez-Pompa, A. 199139) ; 5)Rojas Rabiela, T., 200459)
Merlin-Uribe 43) reports 12 types of vegetables and 37 types of flowers for cultivation in chinampas based on a
questionnaire survey to 100 chinamperos in 2009.
58
(4) The characteristics of open field agriculture types
The parameter for the distinction of ahuejotes in chinampas is the presence of open field
agriculture. Open field agriculture is essential to assess the level of control in the presence of
agricultural elements considered to be alien to traditional chinampa agriculture and landscape. If
ahuejotes are not seen or are barely visible, preserving them may not be justified.
The layer of open filed agriculture was calculated as the agricultural surface free from
greenhouse agriculture. The number of farm holdings employed in greenhouse agriculture was
identified according to data from the Census of Agriculture and Livestock 200743) and the
surface of greenhouse agriculture was calculated for each study units in Excel Microsoft ©.
Afterwards, the categories of agriculture at open field were established in the following range of
scales: 100% open field agriculture, 60% to 99% open field agriculture, 40% to 59% open field
agriculture, 1% to 39% open field agriculture, and 0% open field agriculture. Finally, study units
were characterized according to the categories (See table 5-7).
As can be seen in table 4-7, 58.60% of study units (841 ha, 22 units) were identified as
having 60% to 99% open field agriculture. This is followed by 30.03% of study units (431 ha, 9
units), which feature 100% open field agriculture. Next, 4.59 % of study units (66 ha, 2 units)
can be identified as having 40% to 59% open field agriculture. Finally, 6.78 % of study units (97
ha, 2 units) were identified as featuring 0% to 39% open field agriculture. The results indicate
the presence of greenhouses in almost 70 % of study units. It can be said that greenhouses
appears to be a significant element in the chinampas landscape.
Fig. 4-8 shows that study units, which perform 100% open field agriculture, are located to
the northeast of the study site the most. Study units, which conduct 60% to 99% open field
agriculture, are across chinampas in the west, the center and the east of the study site. The study
units with the 0% to 39 % open filed agriculture were identified to be concentrated toward the
southeast of the study site.
59
Table 4-7 Categories of open field agriculture
Categories
Agricultural
surface (ha)
323.0
Greenhouse
surface (ha)
0.0
% (*)
100 %
Surface
(ha)
431
Study units
Total of
units
9
30.03
1,4,7,8,9,10,13,14,19
60 to 99 %
841
697.6
100.1
58.60
22
40 to 59%
66
58.7
25.6
4.59
2,3,5,6,11,12,15,16,17,18, 20,21,
23,24,25,26,28,29, 32,33, 34,35
22,30
1 to 39 %
85
82.5
65.6
5.92
27
1
0%
12
1,435
7.5
1,169.16
7.5
198.81
0.86
100
31
1
35
2
NOTES:
* Percentage calculated respect to the rural surface in chinampa (1,435 ha)
See table VI in the annex for consulting raw data
Fig. 4-8 Distribution of open field agriculture types
60
(5) The characteristics of agricultural types
Agricultural types assess the variation of agricultural land use characteristics in relation to
the conditions of ahuejote planting. The agricultural types are based on the establishment of a
compound parameter that joins crop diversity and open field agriculture. Here, the layers made
up in this section’s subsections (3) and (4) are retaken once and overlaid to form a single layer.
Layers of crop diversity and open field agriculture were overlaid in Arc Map esri 10 ©. Then,
study units were characterized. As a result, 9 agricultural types were established (Types A to I)
as shown in table 4-8.
The results show that four agricultural types (A, B, D and H) cover approximately 84 % of
the study site. First, the study units of type A were identified to cover 30.03% of chinampas
(378 ha, 7 units). Type A features grain crop cultivation at open field. This is followed by study
units of type H, which cover 21.69 % of chinampas (311 ha, 9 units). Type H is characterized by
mixed crop diversity and 60 to 99% open field agriculture. Next, there are the study units of
type D, which span 21.04 % of chinampas (302 ha, 7 units). Type D features vegetable
cultivation and 60 to 99% open field agriculture. Afterwards, study units of type B were
identified. Their surface covers 15.88 % of chinampas. Type B features grain crop cultivation
and wide expanses devote to open field agriculture. Furthermore, the results also show the study
units of types E and F rate the smallest surface of open field agriculture. Type E and F cover
about 6 % of chinampas that are employed for flower cultivation.
Fig. 4-9 indicates that study units of type A concentrate to the northeast of the study site.
The study units of type H can be seen toward the west of the study site, where it appears to be
interwoven with many other types. The study units of type D form a block in the center of the
study site. Type B covers chinampas in the east of the study site, where it share space with some
study units of type A. The Type F is located in the southeast of the study site.
The distribution of the agricultural types suggests that there is a relationship between the
type of crop and the presence of greenhouses in chinampas. The chinampas, which devote grain
cultivation, are free of greenhouses. On the opposite side, the chinampas, which are employed
for flower cultivation, feature the presence of greenhouses the most. The chinampas, which
conduct vegetable and mixed cultivations, exhibit different levels of presence of greenhouses.
61
Table 4-8 Characteristics of agricultural types
Agriculture
type
A
Crop type
Grains
Open sky
agriculture
○
Surface
(ha)
378.00
B
C
%(*)
Study unit
Total of
units
7
26.34
1,4,7,8,9,14,19
Grains
Vegetables
◎
○
228.00
29.00
15.88
2.02
2,3,5,6,20,21
10.00
6
1
D
E
Vegetables
Flowers
◎
＋
302.00
85.00
21.04
5.92
24,25,26,32,33,34,35
27.00
7
1
F
G
Flowers
Mixed
＋＋
○
12.00
24.00
0.83
1.69
31.00
13.00
1
1
H
I
Mixed
Mixed
◎
●
311.00
66.00
21.69
4.59
11,12,15,16,17,18,23,28,29
22,30
9
2
Totals
1,435
100
35
NOTES:
* Percentage calculated respect to the rural surface in chinampa (1,435 ha)
Categories: ○=100% open field agriculture, ◎=60% to 99% open field agriculture, ●= 40% to 59% open field
agriculture ＋=1% to 39% open field agriculture, ＋＋= 0% open field agriculture
Fig. 4-9 Distribution of agricultural types
62
4.3 Assessment of existing conditions for ahuejote in the urban area in
chinampas
The assessment of land use is an important step to characterize the existing conditions of
ahuejote planting in the urban area in chinampas. The analysis of land use is fundamental to
understand the urban aspects that will influence the management of ahuejote planting in the
future. The analysis of land uses is based on a statistical study of urban density and drain cover ,
using data from the National Census of Population and Dwelling (2010)44) produced by INEGI.
(1) The characteristics of urban density
Urban density types are a compound parameter that assesses the presence of human
settlements in chinampas through the measurement of population density and residential density.
The parameter serves to clarify the chinampas where is ongoing a replacement of agricultural
land use and therefore the alteration of prime agricultural land use. The parameter does not
reflect the distribution of human settlements within the study units. The INEGI mapped the
presence of some agricultural land use within the study units in the urban area in chinampas, but
there is no specific statistical information about that in particular.
To establish the urban density types, first the population density on chinampas was
calculated. The population density indicates the concentration of people per hectare that live in
chinampas. Using data from the Census of Population and Dwelling 2010 44), the coefficient of
population density was calculated ( Population÷ study unit surface) and classified into 3
categories: low (10.00 to 21.75 people per hectare), medium (21.75 to 22.62 people per hectare),
and high (above 22.62 people per hectare).
Second, the housing density in chinampas was calculated, using data from the Census of
Population and Dwelling 2010 44). The housing density expresses the presence of houses per
hectare in the rural area in chinampas. The coefficient of housing density was calculated
(number of houses in chinampa÷study units area (ha) and 3 categories were established: low
(4.5 to 5.60 houses per hectare), medium (above 5.60 to 6.06 houses per hectare) and high
(above 6.06 houses per hectare).
Third, urban density types were established through overlaying the layers of population
density and house density, as can be seen in table 4-9 and fig.4-10. The results produced five
urban density types: A, B, C, D, and E. The type A was identified as having the highest rates of
population density (49.50 people per hectare) and housing density (12.86 houses per hectare).
Study units of type A were observed as spanning 41.3 % of chinampas (173 ha, 4 units). Type A
is followed by type E. Study units of type E were identified as covering 24.4% of chinampas
(101 ha, 5 units). Types E features low densities of population density (23.72 people per
hectare) and housing density (6.46 houses per hectare). Next, study units of types B, C and D
63
were identified as covering 34.3 % of chinampas (144 ha, 3 units). Types B, C and D feature
medium densities of population density (33.86 to 35.08 people per hectare), and housing density
(8.58 to 8.92 houses per hectare).
At this stage it is convenient to look once more at the mean rates of population density and
residential for the boroughs Tlahuac and Xochimilco, which were calculated in chapter 3, in
order to clarify the urban conditions in chinampas. In 2010, the population density in Tlahuac
was 41.89 people per hectare (360,265 people ÷ 8,600 ha) whereas the population density in
Xochimilco was 34.87 people per hectare (415,007 people ÷ 11,900 ha). In comparison with
that, the study units of type A were identified to rate higher population density than Tlahuac.
Furthermore, study units of types B, C and D were observed to rate similarly to Xochimilco in
population density. The study units of type E were identified the only ones with population
density lower than the boroughs.
In regarding to the housing density, in the chapter 3, it was reported that there were 10.49
houses per hectare in Tlahuac and 8.49 houses per hectare in Xochimilco. Comparatively, the
study units of type A have housing density higher than Tlahuac. Study units of types B, C and D
rate residential density similarly to Xochimilco. The study units of type E were identified the
only ones with housing density lower than the boroughs.
The assessment of urban density in chinampas denotes that population density and housing
density in some chinampas can be comparable with urban areas outside the study site.
64
Table 4-9 Characteristics of urban density types
Urban
type
Surface
Population
(ha)
%
(*)
8,563
Number
of
dwelling
s
2,194
Population
density
(People/ha
)
49.50
A
173
41.3
B
12
C
60
2.8
421
107
14.3
2,071
540
D
72
E
101
17.2
2,438
24.4
2,404
Totals
418
100
15,897
Population
density
categories
Housing
density
categories
Study
units
number
Total
of
units
High
Housing
density
(houses/ha
)
12.68
High
4
35.08
High
8.92
Medium
2U,
4U,5U,
9U
11U
34.52
Medium
9.00
High
6U
1
618
33.86
Medium
8.58
Medium
10U
1
655
23.72
Low
6.46
Low
1U,3U,
7U,8U,
12U
5
4,114
38.03
9.84
1
12
NOTES:
Population density: Low>=10.00 <21.75 persons per hectare, Medium >=21.75 <=22.62 persons per hectare, High >22.62 persons per
hectare. The values of each category were calculated using percentiles. Percentile 0=10.00, Percentile 1=130.33
Housing density: Low>=4.5 <5.60 houses persons per hectare, Medium >=5.60 <=6.06 houses persons per hectare, High >6.06 houses
persons per hectare. The values of each category were calculated using percentiles. Percentile 0=4.50, Percentile 1=30.33
See table VII in the annex for consulting raw data.
Fig.4-10 Distribution of urban density types
65
(2) The characteristics of drain cover
The parameter assesses the drain cover in chinampas as a criterion of the prevention of
water pollution in chinampas. The ahuejote is reported to be a tree sensitive to pollution19).
Water pollution in chinampas is reported to be associated with the presence of human
settlements24), 51).
The cover of drain is the rate of houses that have some sort of drain connection, according to
data from the Census of Population and Dwelling 201044). The information that is provided by
the Census indicates the number of houses that have some drain connection to public drain
network, septic tanks or some bodies of water.
The rate of drain cover was calculated and classified into two categories: 1) above average
and 2) below average. Next, the study units were characterized in types according to the
categories, as shown in table 4-10.
The drain cover rates 83% in average in chinampas (3,414 houses ÷ 418 ha). This rate
indicates no full drain cover in chinampas. The study units that rate above average span 35.41%
of chinampas (148 ha, 4 units) and those ones below average cover 64.59 % of chinampas (270
ha, 8 units).
As shown in fig. 4-11, the chinampas with above average drain cover are found on the west
of the study site. On the other hand, the chinampas with below average drain cover are located
in the center-south and the northeast of the study site.
66
Table 4-10 Characteristics of drain cover types
Drain
category
Surface
(ha)
%
Number of
houses with
drainage
1,650
Drain
coverage
(%)*
87
Study unit number
35.41
Number
of
houses
1,905
2U,4U,7U,9U
Total
of
units
4
Above
average
Below
average
Totals
148
270
64.59
2,209
1,764
80
1U,3U,5U,6U,8U,10U,11U,12U
8
418
100
4,114
3,414
83
12
NOTE:
*% of houses with connection to public drain network
See table VII in annex to consult raw data
Fig. 4-11 Distribution of drain cover types in chinampas
67
4.4 Landscape characterization relating to existing conditions of ahuejote in
chinampas
(1) The landscape character types relating to existing conditions of ahuejote in
the rural area in chinampas
The landscape character types provide a concise description of existing conditions relating
to ahuejote planting in the rural area in chinampas. The landscape character types share some
common characteristics and reflect the characteristics features of water conditions and
agricultural land uses. The landscape character types are fundamental to establish the
management categories for conserving ahuejote planting, as will be show in the next chapter.
The landscape character types are the result of overlapping the layers of water unit types,
chinampero density and agricultural types in Arc Map esri 10 © (See sections 4.1 and 4.2 for the
description of layers). Once the layers were overlapped, the study units were characterized into
3 landscape character conditions (A, B, and C) and 21 landscape character types (I to XXI), as
shown in table 4-11. The process that was followed in the characterization of study units is
illustrated by the flow diagram in fig.4-12. The characteristics of landscape character conditions
and landscape types are described below.
Landscape character condition A: Chinampas under agricultural land use
(See table 4-12 & fig.4-13)
The condition features study units under agricultural land use and the presence of canal
networks. The appearance of water resources meet with canal networks. The study units in this
condition covers 617 ha (24 units), approximately 42.99 % of rural area in the study site. The
condition contains the landscape character types I to XIII. Study units of types III, VII and VIII
accommodate together 54.48 % of chinampas in condition A. Type III is the widest one (130 ha,
4 units), followed by type VIII (116 ha, 3 units) and Type VII (14.42 ha, 3 units).
Landscape character condition B: Partly chinampa under agricultural land use
(See table 4-13 & fig.4-14)
The study units in this condition feature agricultural land use, but the appearance of canal
network reflects an alteration of the order of the hydrological system by the presence of floods,
wetland and lake. The surface of study units in condition B covers 451 ha, approximately 31 %
of rural area in the study site. The condition encompasses types XIV to XVIII. The widest type
is XVII (149 ha, 2 units). This is followed by type XVI (105 ha, 2 units). The both together
cover 56.34 % of chinampas in the condition B.
68
Landscape character condition C: Non-chinampa under agricultural land use
(See table 4-14 & fig. 4-15)
The condition indicates study units in agricultural land use but the absence of canal
networks. This area lacks a canal network, which is one of the key elements that contribute to
the legibility of chinampas. The study units in the condition C cover 367 ha, which represent
25.57 % of rural area in the study site. Within the condition C, the types XIX to XXI can be
observed. The type XIX is the widest one (223 ha, 2 units). Its surface is 60.76 % of chinampas
in condition C.
69
Table 4-11 Features of landscape character conditions and landscape
character types in the rural area
Landscape
character
condition
Condition A:
Chinampas under
agricultural land
use
Condition B:
Partly chinampa
under
agricultural land
use
Condition C:
Non-chinampa
under
agricultural land
use
Landscape
character
types
Type I
Water
type
Chinampero
density
Agricultural
type
Surface
(ha)
% (*)
Study units
Total of
units
I
high
A
22
3.65
8
1
Type II
Type III
I
I
high
high
B
D
57
130
9.23
21.06
5,20,21
32,33,34,35
3
4
Type IV
Type V
I
I
high
middle
H
A
43
17
6.96
2.75
18,28,29
14
3
1
Type VI
Type VII
I
I
middle
middle
G
H
24
89
3.88
14.42
13
12,15,17
1
3
Type VIII
Type IX
I
I
low
low
A
B
116
27
18.80
4.37
7,9,19
6
3
1
Type X
Type XI
I
I
low
low
C
F
29
12
4.70
1.94
10
31
1
1
Type XII
Type XIII
I
I
low
low
H
I
30
21
4.84
3.40
11
30
1
1
100
18.84
Type XIV
II
high
E
617
85
27
24
1
Type XV
Type XVI
VII
IV
middle
low
D
D
67
105
14.85
23.28
24
25,26
1
2
Type XVII
Type XVIII
V
III
low
low
H
I
149
45
33.06
9.97
16,23
22
2
1
Type XIX
IX
high
A
451
223
100
60.76
1,4
7
2
Type XX
Type XXI
IX
VIII
middle
low
B
B
51
93
13.89
25.35
2
3
1
1
367
100
4
NOTES:
*% respect to the surface of each basic rural condition.
Water types: I= Presence of canal network , II to VII= Presence of canal network combined with wetland conditions, VIII to
IX= Absence of canal network
Chinampero density: High >4.35 p/ha , Middle >3.02 p/ha <=4.35 p/ha, Low>0.51 p/ha <=3.02 p/ha
Agricultural types: A= grains crops & 100% open field agriculture, B= grain crops & 60% to 99% open field agriculture, C=
vegetable crops & 100% open field agriculture, D = vegetables & 60% to 99% open field agriculture, E= flower crops & 1%
to 39% open field agriculture, F= flower crops & 0% open field agriculture, G= Mixed crops & 100% open field agriculture,
H=Mixed crops & 60 to 99 % open field agriculture, I= mixed crops & 40% to 59% open field agriculture
70
Fig.4-12 Flow for the characterization of study units in the rural area in chinampas
(see page 76 to follow to 2 )
71
Table 4-12 Features of landscape character types within the condition A
Landscape
character
condition
Condition A:
Chinampas under
agricultural land
use
Landscape
character
types
Type I
Water
type
Chinampero
density
Agricultural
type
Surface
(ha)
% (*)
Study units
Total of
units
I
high
A
22
3.65
8
1
Type II
Type III
I
I
high
high
B
D
57
130
9.23
21.06
5,20,21
32,33,34,35
3
4
Type IV
Type V
I
I
high
middle
H
A
43
17
6.96
2.75
18,28,29
14
3
1
Type VI
Type VII
I
I
middle
middle
G
H
24
89
3.88
14.42
13
12,15,17
1
3
Type VIII
Type IX
I
I
low
low
A
B
116
27
18.80
4.37
7,9,19
6
3
1
Type X
Type XI
I
I
low
low
C
F
29
12
4.70
1.94
10
31
1
1
Type XII
Type XIII
I
I
low
low
H
I
30
21
4.84
3.40
11
30
1
1
617
100
24
NOTES:
*% respect to the basic rural conditions.
Water types: I= Presence of canal network
Farmer density: High >4.35 per hectare , Middle >3.02 per hectare <=4.35 per hectare, Low>0.51 per hectare <=3.02 per
hectare
Traditional agricultural types: A= grains crops & 100% open field agriculture, B= grain crops & 60% to 99% open field
agriculture, C= vegetable crops & 100% open field agriculture, D = vegetables & 60% to 99% open field agriculture, E=
flower crops & 1% to 39% open field agriculture, F= flower crops & 0% open field agriculture, G= Mixed crops & 100%
open field agriculture, H=Mixed crops & 60 to 99 % open field agriculture, I= mixed crops & 40% to 59% open field
agriculture
Fig.4-13 Distribution of rural character types within the condition A
72
Table 4-13 Features of rural character types within the condition B
Landscape
character
condition
Condition B:
Partly
chinampa under
agricultural
land use
Landscape
character
types
Type XIV
Water
type
Chinampero
density
Agricultural
type
Surface
(ha)
% (*)
Study units
Total of
units
II
Type XV
Type XVI
VII
IV
high
E
85
18.84
27
1
middle
low
D
D
67
105
14.85
23.28
24
25,26
1
2
Type XVII
Type XVIII
V
III
low
low
H
I
149
45
33.06
9.97
16,23
22
2
1
451
100
7
NOTES:
*% respect to the basic rural conditions.
Water types: II to VII= Presence of canal network combined with wetland conditions
Farmer density: High >4.35 per hectare , Middle >3.02 per hectare <=4.35 per hectare, Low>0.51 per hectare <=3.02
per hectare
Traditional agricultural types: A= grains crops & 100% open field agriculture, B= grain crops & 60% to 99% open field
agriculture, C= vegetable crops & 100% open field agriculture, D = vegetables & 60% to 99% open field agriculture, E=
flower crops & 1% to 39% open field agriculture, F= flower crops & 0% open field agriculture, G= Mixed crops & 100%
open field agriculture, H=Mixed crops & 60 to 99 % open field agriculture, I= mixed crops & 40% to 59% open field
agriculture
Fig. 4-14 Distribution of rural character types within the condition B
73
Table 4-14 Features of landscape character types within the condition C
Landscape
character
condition
Condition C:
Non-chinampa
under
agricultural
land use
(367 ha)
Landscape
character
types
Type XIX
Water
type
Chinampero
density
Agricultural
type
Surface
(ha)
% (*)
Study units
IX
high
A
223
60.76
1,4
Total
of
units
2
Type XX
Type XXI
IX
VIII
middle
low
B
B
51
93
13.89
25.35
2
3
1
1
367
100
4
NOTES:
*% respect to the basic rural conditions.
Water types: VIII to IX= Absence of canal network
Farmer density: High >4.35 per hectare , Middle >3.02 per hectare <=4.35 per hectare, Low>0.51 per hectare
<=3.02 per hectare
Traditional agricultural types: A= grains crops & 100% open field agriculture, B= grain crops & 60% to 99% open
field agriculture, C= vegetable crops & 100% open field agriculture, D = vegetables & 60% to 99% open field
agriculture, E= flower crops & 1% to 39% open field agriculture, F= flower crops & 0% open field agriculture, G=
Mixed crops & 100% open field agriculture, H=Mixed crops & 60 to 99 % open field agriculture, I= mixed crops
& 40% to 59% open field agriculture
Fig.4-15 Distribution of rural character types within the condition C
74
(2) The landscape character types relating to existing conditions of ahuejote in
the urban area in chinampas
The landscape character types provide a concise description of existing conditions relating
to ahuejote planting in the urban area in chinampas. The landscape character types share some
common characteristics and reflect the features of water conditions, urban density and drain
cover. The character types are fundamental to establish the management categories for
conserving the ahuejote planting, as will be show in the next chapter.
The characterization gathers the layers of water unit types, urban density types and drain
cover types in a new single layer, which was processed in Arc Map esri 10 ©. The process that
was followed in the characterization is illustrated by the flow diagram in fig.4-16. The new
layer was used as reference to characterize the study units into 2 landscape character conditions
(D and E) and 8 landscape character types (XXII to XXIX) as shown in table 4-15. The
landscape character conditions (D and E) and respective landscape character types are described
as followed.
Landscape character condition D: Chinampas with presence of urban land use
(See table 4-15 & fig.4-17)
The condition features study units with the presence of canal networks and some human
settlements over agricultural land use. The appearance of water seems in order with the
characteristics hydrologic system of canal network in chinampas. The urban density records
medium-high concentrations of population and houses. The study units in this condition cover
324 ha (9 units), 77.51 % of urban area in the study site. The condition contains the landscape
character types XXII to XXVIII. The type XXII is the widest one, which covers 41.66 % of
chinampas (135 ha, 3 units). The second widest is the type XXV, 22.22% of chinampas (72 ha, 1
unit). The third widest is the type XXIV, which is 18.51 % (72 ha, 1 unit) of chinampas.
Landscape character condition E: Non-chinampas with presence of urban land use
(See table 4-15 & fig.4-17)
The condition is characterized by study units where there is the absence of canal networks
but some human settlements over agricultural land use. Historically, the study units in the
condition were chinampas areas (See chapter 1.1). The urban density shows medium
concentrations of population and houses. The study units in this condition covers 94 ha (4 units),
22.48 % of urban area in the study site. The condition encompasses the landscape character
types XXVIII to XXIX. The type XXIX is the widest one. Its surface covers 87.23 % of
chinampas (82 ha, 3 units) within the condition E.
75
Fig.4-16 Flow for the characterization of study units in the urban area in
chinampas (see page 71 to back to 1 )
76
Table 4-15 Features of landscape character types within the urban area
Landscape
character
condition
Condition
D:
chinampas
with
presence of
urban land
use
Condition E:
non-chinam
pas with
presence of
urban land
use
Landscape
character
type
Surface
(ha)
% (*)
Water
unit
Urban
type
Drain cover
Type XXII
135
41.66
I
A
Type XXIII
38
11.72
I
Type XXIV
60
18.51
Type XXV
72
Type XXVI
Type XXVII
Study unit
Total of
number
units
above average
2U,4U,9U
3
A
below average
5U
1
I
C
below average
6U
1
22.22
I
D
below average
10U
1
13
4.04
I
E
above average
7U
1
6
1.85
I
E
below average
3U
1
Totals
324
100
Type
XXVIII
12
Type XXIX
82
Totals
94
12.77
87.23
100
8
IX
B
VIII,
IX
E
below
average
below
average
11U
1
1U,8U,12U
3
4
NOTES:
*Percentage calculated respect to the respective basic urban conditions in chinampas
Water types: I= Presence of canals, VIII to IX= Absence of canals
Urban types: A type: high population density and high dwelling density, B type: high population density and
medium dwelling density , C type: Medium population density and high dwelling density , D type: medium
population density and medium dwelling density , E type: low population density and low dwelling density
Drain coverage= above average >83% of houses with connection to public drain network, below average< 83% of
houses with connection to public drain network
Fig.4-17 Distribution of landscape character types within the urban area in
chinampas
77
CHAPTER FIVE
THE MANAGEMENT CATEGORIES FOR THE CONSERVATION OF AHUEJOTE
The management categories set the basis for the conservation of ahuejote as a key element in the
chinampa landscape. The management categories are fundamental to identify the legibility of
chinampas, the significance of ahuejote in chinampas, and the focus of ahuejote conservation.
5.1 The legibility of chinampa structure from the distribution of ahuejote
To assess the legibility of chinampa structure, the relationship between the ahuejote planting
and water structure was investigated. The appraisal that the water structure has, visually and
functionally, in conserving ahuejote planting is to be acknowledged as an essential parameter of
identity in the chinampa landscape.
To investigate the legibility of chinampa structure, it is worthy to once again look at the
landscape character types, which were obtained in section 4.4, and study particularly the water
conditions. The prime condition to recognize a chinampa is the presence of canal networks. In
the rural area, the study units that belong to the landscape character conditions A and B (Types I
to XVIII and types XXVIII-XXIX) can be considered as chinampas because there is the
presence of canal networks and ahuejote planting. The landscape character condition C observes
the absence of canal networks; therefore, the prime water conditions for the legibility of
chinampas cannot be confirmed. About the urban area, the study units that belong to the urban
conditions D (Types XXVIII-XXIX) can be considered as chinampas. The study units in
conditions D achieve the presence of canal networks and ahuejote planting. The landscape
character condition E observes the absence of canal networks; therefore, the presence of
chinampas cannot be confirmed
As a result, the study units to be considered as having some chinampas cover 1,392 ha (39
units). 1,068 ha of chinampas are in the rural area but 324 ha of chinampas in the urban area.
The location of chinampas can be observed in fig.5-1.
78
Fig. 5-1 Distribution of chinampas
Once the chinampas were recognized, the next step was to establish if there was some
relationship between the water conditions and the distribution of ahuejote planting across
chinampas. To achieve that aim, the layer of ahuejote density types was overlapped on the layer
of water unit types. (See section 4.1 for the description of ahuejote density types and water unit
types).
As a result, the study units with high density of ahuejotes were identified by coinciding with
the water type I the most (50.07 % of chinampas, 697 ha, 17 units), as can be seen in table 5-1.
Water type I features the presence of canal networks. On the other hand, the study units with
low densities of ahuejote were observed in coincidence with water unit types II and IV to VII,
which feature the alteration of canal network and the presence of lake or wetland. In conclusion,
the relationship between the structure of canal networks and the permanency of ahuejote
planting it can be confirmed.
Table 5-1 Distribution of ahuejote from the water types
Ahuejote density
types
High
Water units types
% (*)
Study units number
I
Surface
(ha)
534
Total of
units
17
38.36
Medium
I
163
11.71
8,11,12,13,14,17,18,19,20,21,28,
29, 34,35,4U,9U,10U
5,9,10,15,30,3U,7U
Medium
III
45
3.23
22
1
Low
I
244
17.53
6,7,31,32,33,2U,5U,6U
8
Low
II, IV to VII
406
29.17
27,25,16,23,24,26
6
1,392
100
7
39
79
5.2 The significance of ahuejote from the landscape character types
The assessment of ahuejote planting from the landscape character types is fundamental to
determine the characteristics features of sites where the ahuejote continues to be a key element
of chinampa landscape. The assessment consisted of two steps. First, the study units were
accommodated within three categories according to the ahuejote density (high, medium and
low). Second, the study units were classified by landscape character type. The distribution of
study units can be seen in table 5-2 and table 5-3.
The table 5-2 contains the information on the study units in the rural area in chinampas
(landscape character conditions A and B). The table 5-2 shows that the study units with high
densities of ahuejote equals to 330 ha (14 units) or 30% of the rural area in chinampas. Here, the
type III is the widest (63 ha), followed by the type VII (50 ha), type VIII (48 ha) and type IV
(43 ha). The four types observe the presence of canal networks, but different levels of
chinampero density and various agricultural types.
The table 5-2 also shows that the study units with low densities of ahuejote cover 549 ha (11
units), which equal to 51.40 % of the rural area in chinampas. Here, the type XVII is the widest
(149 ha), followed by the type XVI (105 ha), and the type XIV (85 ha). The common aspect to
types XVII, XVI and XIV is the alteration of canal networks due to the presence of lake or
wetland. Based on this observation, it is worthy to note that the study units with low density of
ahuejote cover a major surface in comparison with the study units with high density of ahuejote.
The table 5-3 shows the information on the study units in the urban area (landscape
character condition D). As can be seen in the table 5-3, the study units with high densities of
ahuejote cover 204 ha. It is 67.10% of the urban area in chinampas. Here, the widest is the type
XXII (132 ha), which features the presence of canal networks, high urban density and drain
cover above the average. The study units with low densities of ahuejote spans 101 ha. Their
surface equals to 33.22 % of chinampas in the urban area. Here, the widest type is XXIV (60 ha),
which features the presence of canal networks, medium urban density and drain cover that is
below the average.
80
Table 5-2 Distribution of ahuejote from the landscape character types in the
rural area of chinampas
Ahuejote
density
Water
types
Chinampero
density
Agricultura
l type
Rural
character
type
Surface
(ha)
High
I
High
High
I
High
A
Type I
22
B
Type II
33
High
I
High
High
I
High
D
Type III
63
H
Type IV
43
High
I
Medium
High
I
Medium
A
Type V
G
Type VI
High
I
Medium
High
I
Low
H
A
High
I
Low
H
Type XII
% (*)
Study
units
Total of
study
units
6.67
8
1
10.00
20,21
2
19.09
34,35
2
13.03
18,28,29
3
17
5.15
14
1
24
7.27
13
1
Type VII
50
15.15
12,17
2
Type VIII
48
14.55
19
1
11
30
9.09
330
100
1
14
Medium
I
High
B
Type II
24
12.70
5
1
Medium
I
Medium
H
Type VII
39
20.63
15
1
Medium
I
Low
A
Type VIII
31
16.40
9
1
Medium
I
Low
C
Type X
29
15.34
10
1
Medium
I
Low
I
Type XIII
21
11.11
30
1
Medium
III
Low
I
Type XVIII
45
23.81
22
1
189
100
Low
I
High
D
Type III
67
12.20
32.33
2
Low
I
Low
B
Type IX
27
4.92
6
1
Low
I
Low
A
Type VIII
37
6.74
7
1
6
Low
I
Low
F
Type XI
12
2.19
31
1
Low
II
High
E
Type XIV
85
15.48
27
1
Low
VII
Medium
D
Type XV
67
12.20
24
1
Low
IV
Low
D
Type XVI
105
19.13
25,26
2
Low
V
Low
H
Type XVII
149
27.14
16,23
549
100
2
11
NOTES:
*% according to the area for each ahuejote density type
Water types: I= Presence of canal network , II to VII= Presence of canal network combined with wetland conditions
Chinampero density: High >4.35 per hectare , Middle >3.02 per hectare <=4.35 per hectare, Low>0.51 per
hectare <=3.02 per hectare
Agricultural types: A= grains crops & 100% open field agriculture, B= grain crops & 60% to 99% open field
agriculture, C= vegetable crops & 100% open field agriculture, D = vegetables & 60% to 99% open field agriculture,
E= flower crops & 1% to 39% open field agriculture, F= flower crops & 0% open field agriculture, G= Mixed crops
& 100% open field agriculture, H=Mixed crops & 60 to 99 % open field agriculture, I= mixed crops & 40% to 59%
open field agriculture
81
Table 5-3 Distribution of ahuejote from the landscape character types in the
urban area of chinampas
Ahuejote
density
water
unit
Urban
type
Drain cover
type
Urban character
type
Surface
(ha)
%(*)
High
I
A
High
I
D
Medium
I
E
above average
Type XXVI
Medium
I
E
below average
Type XXVII
64.70
Study
unit
numbers
4u,9u
Total of
study
units
2
above average
Type XXII
132
below average
Type XXV
72
35.30
10u
1
204
100
13
68.42
7u
1
6
31.58
3u
1
19
100
3
Low
I
A
above average
Type XXII
3
2.98
2u
1
Low
I
A
below average
Type XXIII
38
37.62
5u
1
Low
I
C
below average
Type XXIV
60
59.40
6u
1
101
100.00
8
NOTES
*% according to the area for each ahuejote density type
Water types: I= Presence of canals, VIII to IX= Absence of canals
Urban types: A type: high population density and high dwelling density, B type: high population density and medium
dwelling density , C type: Medium population density and high dwelling density , D type: medium population density
and medium dwelling density , E type: low population density and low dwelling density
Drain coverage= above average >83% of houses with connection to public drain network, below average< 83% of
houses with connection to public drain network
82
5.3 The management categories for the conservation of ahuejote
The management categories aim to establish the focus on conserving ahuejote as a key
element in chinampas landscape, using as a reference the assessment process that was carried
out in section 5.2. The establishment of management categories retakes the distinction of
existing conditions in chinampas (landscape character types) and the ahuejote density
characteristics. The management categories are spatially referred to a three-zoning scheme in
coincidence with the three landscape character conditions (A, B, and D) in chinampas. The
scheme is organized by type of land use, urban or rural, and proximity to wetland.
The management categories aim two objectives. The first is to secure the existing ahuejotes
in the areas of high density of ahuejote. The second is to plant new ahuejotes in the areas of
low-medium densities of ahuejote. In order to achieve the objectives, the focus of management
categories targets essentially on mitigation measures and where possible the enhancement of the
existing conditions for conserving ahuejote. To establish the distinct levels of mitigation, the
Guidelines for Landscape and Visual Impact Assessment (2002)83 was utilized as reference. As
a result, four management categories were established and the targets for the landscape
character types were clarified. The approach of management categories is described as follow:
1. Enhancement: the category is to be considered when the existing condition can be used in
favor of the conservation of ahuejote. The category is to explore the opportunities and
appropriateness of landscape change while maintaining qualities of landscape. The existing
conditions could help to keep, restore or reconstruct the landscape character in chinampas.
2. Avoidance: the category is to be considered when the existing conditions could be used in
favor of the conservation of ahuejote. Avoidance aims to prevent any adverse effect on
landscape through carefully guiding future landscape change.
3. Reduction: the category is to be considered when the existing conditions already show the
presence of some alteration of the characteristic of features in chinampas. In this case, the
presence of some negative effect could not be avoided and the reduction of any conflict with the
landscape is to be aimed. Reduction could increase the ability of the landscape to accommodate
some changes, while keeping the essential character of the area appropriately to the
circumstances.
4. Compensation: the category is to be considered when there is the loss of some existing
characteristic or element essential to chinampas. Compensatory measures often include the
provision of new elements to cover the loss.
The targets for landscape character types were established taking into account the different
assessment scales for water structure, agricultural land use and urban land use, as illustrating in
fig. 5-2. The contents of targets for each planning parameter are explained in table 5-4.
Zone A (or landscape character condition B) (See table 5-5 & fig. 5-3)
83
In the zone A, the alteration of primer water structure would require an intervention in
reducing the effects of wetland on chinampas and recover canal network in favor of chinampa
agriculture and, consequently, the restoration of ahuejote planting. Potential conflicts between
the conservation of ahuejote and wetland would require where possible to accommodate and or
restrain the expansion of wetland on chinampas. The intervention of new agents in the
management of ahuejote can help to care of it because the absence of chinamperos. Here,
initially, it is required the restructuration of canal network. This would be followed by the
densification of ahuejote planting. Afterwards, it would be required explore the needs to take
care of ahuejote. Furthermore, with satisfying the demands for cultivation, the attention of any
change in agriculture methods or crops should be not only limited to maintain agricultural
practices at open field but also to explore the opportunities to reintroduce agricultural practices
that help to encourage some use of ahuejote.
Zone B (or landscape character condition A) (See table 5-6 & fig. 5-4)
In the zone B, the water structure keep canal networks, which are a characteristic feature
that can really contribute to conserve ahuejote planting or facilitate the densification of it where
required. However, it would require incorporating new agents in the attention and care of
ahuejote where there is the absence of chinampero. With satisfying demands for cultivation, any
change in agriculture methods or crops should ensure agricultural practices at open field in order
to encourage the use of ahuejote and then limit the appearance of uncharacteristic elements to
chinampas.
.
Zone C (or basic urban condition D) (See table 5-7 & fig. 5-5)
In the zone C, the water structure keeps canal networks and therefore it can help to conserve
ahuejote forest or facilitate the densification of it where required. However, the urban density
and drain cover are to be carefully investigated to find out ways to accommodate ahuejote even
though the urban spread goes on. The guidance of urban occupation and the prevention of water
pollution are key goals to be achieved.
84
Notes: number within ( ) indicates the target of each management category. See table 5-4 for the
characteristics of each parameter and the contents for each management category’s target.
Fig. 5-2 Management categories for conservation of ahuejote
85
Table 5-4 Contents of management categories for the conservation of
ahuejote
Assessment types
(Refers to chapter 4)
Features
Management
categories
Main target
Water unit type I
Existence of
canal network in
order
Enhancement
(1) High density of ahuejote.
The aim is to maintain canal structure and then ensure
the basic structure of chinampas.
Water unit type I
Existence of
canal network in
order
Enhancement
(2) Low-medium density of ahuejote.
The aim is to maintain canal structure and explore the
opportunities of how it can contribute to the
densification of ahuejotes and consequently help to
reconstruct the basic structure of chinampas.
Water units types II to
VII
Alteration of
canal network
Reduction
(1) Low-medium density of ahuejote.
The aim is to recover canal networks to establish the
basic water conditions to conserve ahuejotes. The
reduction of possible conflicts between the
conservation of wetland and the conservation of
ahuejotes require analyzing where possible to
accommodate and restrain the expansion of lake and or
wetland on chinampas.
High density
5.79 chinamperos
per hectare
Avoidance
(1) High density of ahuejote.
The aim is to endorse the chinampero permanency in
chinampa agriculture, particularly the sort of chinampa
agriculture that incorporates the use of ahuejote in
agriculture.
High density
5.79 chinamperos
per hectare
Avoidance
Low to medium
density
1.77 to 3.62
chinamperos per
hectare
Compensation
Low to medium
density
1.77 to 3.62
chinamperos per
hectare
Compensation
(2) Low-medium density of ahuejote.
The aim is to endorse the chinampero permanency in
chinampa agriculture and explore the opportunities of
encouraging the people participation in the
densification and care of ahuejote.
(1)High density of ahuejote.
The aim is to compensate the absence or loss of
chinampero in the attention and care of ahuejotes. The
participation of other agents in the care of ahuejotes is
to be investigated.
(2) Low-medium density of ahuejote.
The compensation measures are to be followed by the
densification of ahuejote forest. The absence or loss of
chinampero in chinampa in the attention and care of
ahuejotes require new agents to avoid to loss again
ahuejotes.
To be continued in the next page…
Rural area of chinampas
1. Water unit
2. Chinampero density
86
…comes from the previous page
Assessment types
(Refers to chapter 4)
Features
Management
categories
Main target
Type A
Grain cultivation,
100% agriculture
at open field
Enhancement
(3) All densities of ahuejote
The aim is to maintain open field agriculture if any
change of agriculture methods or crops happens. If
water structure and chinampero density are
appropriate, there is a real opportunity to ensure the
conservation of ahuejotes in chinampas.
Types B, C, D, G, H
and I
Vegetables, grain
and mixed
cultivation; 40 to
90% of
agriculture at
open field.
Reduction
Types E and F
Flowers; 0 to
39 % agriculture
at open field.
Reduction
(2) All densities of ahuejote
With satisfying the demands of cultivation, the aim is
to avoid the introduction or expansion of agricultural
methods that provoke replacing traditional agriculture
in chinampas. Agricultural methods and crops provide
reasons to use ahuejote in agriculture and consequently
keep the basic structure of chinampas.
(3) Low-medium density of ahuejote
Where possible, the aim is to maintain some open field
agriculture to keep ahuejotes in chinampas. The
opportunities to reintroduce the use of ahuejote in
agriculture are to be explored.
Population
density of 38.03
persons per
hectare in
average;
Residential
density of 9.84
houses per
hectare in
average
Reduction
(4) All densities of ahuejote
The aim is to investigate the opportunities of
accommodating ahuejotes while the dispersion of
human settlements occurs and then keep the basic
structure of chinampa.
Drain cover of
83 % in average.
There is not full
drain cover in
chinampas
Reduction
(5) All densities of ahuejote
The aim is to prevent water pollution from wastewater
effluents while the dispersion of human settlements
happens. It requires contention measures to avoid
pollutants to spread and affect ahuejotes.
3. Agricultural types
4. Urban density types
Types A, B, C, D and
E
5. Drain cover type
Above average
Below average
87
Table 5-5 Management categories in the zone A in chinampas
Management
types
Study units number
Ahuejote
density
Planning parameters
Water
units
Chinampero
density
Agricultural
types
Surface
(ha)
%(*)
Total
of
units
Zone A
I
27
Low-medium
◎(1)
□(2)
◎(3)
85
18.85
1
II
16, 22,23,24,25,26,
Low-medium
◎(1)
■(2)
◎(2)
366
81.15
5
451
100
7
○
□
■
Notes:
=Enhancement, ◎=Reduction,
= Avoidance
=Compensation
Number within ( ) indicate the main target of management category.
See table-5-4 for the focuses on the targets for each management categories
Fig. 5-3 Distribution of management categories in the zone A
88
Table 5-6 Management categories in the zone B in chinampas
Management
types
Study units number
Ahuejote
density
Planning parameters
Agricultural
types
Surface
(ha)
%(*)
Total
of
units
Water
units
Chinampero
density
High
○(1)
□(1)
○(3)
22
3.57
1
Zone B
III
8
IV
18,20,21,28,29,34,35
High
○(1)
□(1)
◎(2)
139
22.53
7
V
11,12,13,17
High
○(1)
■(1)
◎(2)
104
16.86
4
VI
14,19
High
○(1)
■(1)
○(3)
65
10.53
2
VII
5,32,33
Low-medium
○(2)
□(2)
◎(2)
91
14.75
3
VIII
6,10,15,30
Low-medium
○(2)
■(2)
◎(2)
116
18.80
4
IX
7,9
Low-medium
○(2)
■(2)
○(3)
68
11.02
2
X
31
Low-medium
○(2)
■(2)
◎(3)
12
1.94
1
617
100
24
○
□
■
Notes:
=Enhancement, ◎=Reduction,
= Avoidance
=Compensation
Number within ( ) indicate the main target of management category.
See table-5-4 for the focuses on the targets for each management categories
Fig. 5-4 Distribution of management categories in the zone B
89
Table 5-7 Management categories in the zone C in chinampas
Management
types
Study unit
numbers
Ahuejote
density
water
unit
Urban
type
Drain cover
type
Surface
(ha)
%(*)
Total
of
study
units
Zone C
XI
4u,9u, 10u
High
○(1)
◎(4)
◎(5)
204
62.96
3
XII
2u, 3u, 5u,
6u, 7u
Low-medium
○(2)
◎(4)
◎(5)
120
37.03
5
324
100.00
8
○
Notes: =Enhancement, ◎=Reduction,
Number within ( ) indicate the main target of management category.
See table-5-4 for the focuses on the targets for each management categories
Fig.5-5 Distribution of management categories in zone C
90
5.4 Discussion and conclusions
The study has investigated the basic potential of existing conditions to conserve ahuejote as
a key landscape element of chinampa based on the establishment of landscape character types
and management categories. The study assessed the conditions in the urban area (324 ha) and
rural area (1,068 ha), in chinampas. The landscape character types can be seen as the baseline of
the existing conditions of ahuejotes in chinampas, whereas the management categories can be
seen as the targets to achieve for future planning efforts for the conservation of ahuejotes.
The landscape character types were established on the basis of a statistical study of water
cover, agricultural land use and urban land use. 5 landscape character conditions were identified
and 29 landscape character types were defined. In the rural area, 3 landscape character
conditions and 21 landscape types were identified. In the urban area, 2 landscape character
conditions and 8 landscape character types were recognized. The landscape character types
helped clarify two aspects about the existing conditions of ahuejotes in chinampas.
First, the optimal combination of water structure and agriculture for the conservation of
ahuejote still persists; however, it coexists with other emerging conditions for ahuejote. These
emerging conditions involve the distinction of a variety of characteristics in both urban and rural
land uses in chinampas.
Second, the ahuejote still continues to be a key landscape element in 38.36 % of chinampas
(534 ha). The zone B in the rural area constitutes the primary site of the major reserve of
ahuejotes (330 ha), however, the zone C in the urban area also appears to have an important
reserve of ahuejotes (204 ha).
The results show the need of separating the planning policy into finer levels of management
according to a variety of planning parameters to provide a basis for future efforts in conserving
ahuejotes. Four levels of management were investigated and the main targets for five sets of
planning parameters were defined. This achieved two objectives. The first objective was to
secure the existing reserves of ahuejote, and the second was to establish new ahuejotes where
required.
To accomplish the objectives, the need of ensuring the appropriate state of the canal network
was identified as the prime condition. The study confirmed that in the Zone B, types III, IV, V
and VI show possibilities of conserving the existing high densities of ahuejotes due to the
presence of canal networks. In the same zone, there is the possibility of increasing the density of
ahuejotes in types VII, VIII, IX and X because they appear to have canal networks. It could
increase in 287 ha chinampas, wherein ahuejotes were a key element of landscape.
In the zone C, type XI appears to have potential in conserving ahuejotes due to the presence
of canal networks. Type XII also shows to have canal networks, therefore, there are possibilities
to increase the density of ahuejotes in some 120 ha.
91
In the zone A, types I and II were identified as the types requiring some mitigation
measures in order to reduce the impact from the expansion of the lake and wetland, and recover
the canal network to prepare the terrain for future efforts in planting ahuejotes. If the canal
network is recovered, new ahuejotes can be planted in some 451 ha of chinampas.
Any effort in planting new ahuejotes or conserving the existing ones requires people to take
care of the ahuejotes. With regards to the attention and care of ahuejotes, the density of
chinamperos in the rural area was assessed. Two levels of management categories relating to the
density of chinamperos were identified. The first level focused on the efforts to endorse the
permanency of chinampa in current agriculture. The second level aimed to compensate for the
absence of chinamperos. In the zone B, the results show that compensation measures are
required in 365 ha of chinampas. In zone A, 81.15% of chinampas required compensation
measures in the care of ahuejotes. It is worthy to note that the study did not assess the
willingness of chinamperos to take care of ahuejotes; therefore, future studies should be focused
on investigating the potential related to such aspect.
The study also assessed the agricultural characteristics of rural land use through the
investigation of crop diversity and agricultural methods. The study confirmed much presence of
greenhouses in chinampas. From this, the opportunities of visual enhancement of ahuejotes are
to be carefully studied.
Regarding the urban area, the study helped to understand that an important reserve of
ahuejotes (204 ha) is now subject to new conditions that appear to gradually abandon the
traditional relationship of ahuejote and chinampas based on agriculture. The recognition of the
reality of informal settlements for the conservation of ahuejote has been stated, but it requires
careful investigation to discern how they could positively act as agents of conservation of
ahuejotes.
The study contributes to understand that the conservation of ahuejotes as a key landscape
element in the chinampa World Heritage Site of Milpa Alta, Tlahuac and Xochimilco relies on
recognizing the diversity of existing conditions in chinampas. The recognition of such variety is
linked to the conservation of special designations for chinampas. The effectiveness of the
designations in protecting key sites is often questioned because of the strict approach in the
management of the landscape, but they are, at the same time, instruments to plan sites 78, 47). As
addressed in chapter 3, the focus on special designations on chinampas are principally ones of
control but that, at the same time, they have been overwhelmed by environmental decline and
urban pressure. Despite the arguments for and against designations, they constitute a mainstay
of the planning policy in Mexico City. The management of ahuejotes illustrates the need of
more sympathetic approaches in the establishment of land use management that supports the
maintenance of characteristic features of chinampas.
92
List of tables
Chapter 1
Table 1-1 Selected literature relating to chinampa
Table 1-2 Links between the cultural heritage criteria, cultural landscape
categories and cultural criteria of nomination of chinampa
Chapter 2
Table 2-1 Special designations for chinampas
Table 2-2 Surface of study units in chinampas
Table 2-3 Features of study Units in the rural area in chinampas
Table 2-4 Features of study Units in the urban area in chinampas
Chapter 3
Table 3-1 General features of the conservation land
Table 3-2 Distribution of houses in boroughs Xochimilco and Tlahuac
Table 3-3 Contents of land use plans at regional scale relating to chinampa
Table 3-4 Contents of land use plans at site scale relating to chinampa
Table 3-5 Main Features of land use plans relating to chinampa
Chapter 4
Table 4-1 Distribution of ahuejote densities in chinampas
Table 4-2 Features of water unit types in chinampas
Table 4-3 Distribution of land uses in chinampa
Table 4-4 Categories of chinampero density
Table 4-5 Characteristics of crop diversity types
Table 4-6 Variety of crops in chinampas
Table 4-7 Categories of open field agriculture
Table 4-8 Characteristics of agricultural types
Table 4-9 Characteristics of urban density types
Table 4-10 Characteristics of drain cover types
Table 4-11 Features of landscape character conditions and landscape
character types in the rural area
Table 4-12 Features of landscape character types within the condition A
Table 4-13 Features of rural character types within the condition B
To be continued in the next page…
93
…comes from the previous page
Table 4-14 Features of landscape character types within the condition C
Table 4-15 Features of landscape character types within the urban area
Chapter 5
Table 5-1 Distribution of ahuejote from the water types
Table 5-2 Distribution of ahuejote from the landscape character types in
the rural area of chinampas
Table 5-3 Distribution of ahuejote from the landscape character types in
the urban area of chinampas
Table 5-4 Contents of management categories for the conservation of
ahuejote
Table 5-5 Management categories in the zone A in chinampas
Table 5-6 Management categories in the zone B in chinampas
Table 5-7 Management categories in the zone C in chinampas
94
List of figures
Chapter 1
Fig.1-1 Chinampas in the Basin of Mexico in the 16th Century
Fig.1-2 Scheme of chinampas
Fig. 1-3. Use of almacigo in chinampas
Fig.1-4 Ahuejote features
Fig.1-5 Some plagues that affect ahuejote
Chapter 2
Fig.2-1 Location of study site
Fig.2-2 Surroundings of study site
Fig.2-3 Sites of special designations relating to chinampa
Fig.2-4 Distribution of study units and study units samples
Fig.2-5 Research flow
Chapter 3
Fig. 3-1 Land use zoning in the Federal District
Chapter 4
Fig.4-1. Distribution of ahuejote in chinampas
Fig.4-2 Water across chinampas
Fig.4-3 Volume of groundwater extracted in Xochimilco and Tlahuac
Fig.4-4 Ahuejote and the water levels in chinampas
Fig.4-5 Distribution of water units types in chinampas
Fig.4-6 Distribution of chinampero density type
Fig.4-7 Distribution of crop diversity
Fig.4-8 Distribution of open field agriculture types
Fig.4-9 Distribution of agricultural types
Fig.4-10 Distribution of urban density types
Fig.4-11 Distribution of drain cover types in chinampas
Fig.4-12 Flow for the characterization of study units in the urban area in
chinampas
Fig.4-13 Distribution of rural character types within the condition A
Fig. 4-14 Distribution of rural character types within the condition B
To be continued in the next page…
95
…comes from the previous page
Fig.4-15 Distribution of rural character types within the condition C
Fig.4-16 Flow for the characterization of study units in the urban area in
chinampas
Fig.4-17 Distribution of landscape character types within the urban area in
chinampas
Chapter 5
Fig.5-1 Distribution of chinampas
Fig.5-2 Management categories for conservation of ahuejote
Fig.5-3 Distribution of management categories in the zone A
Fig.5-4 Distribution of management categories in the zone B
Fig.5-5 Distribution of management categories in the zone C
96
Notes and references
1)
There are four species of willows reported in the Basin of Mexico. Besides ahuejote, the
other species of willow trees are: Salix cana Mart. & Gal., Salix mexicana seeme, and Salix
paradoxa H.B.K.
2)
The climate classification is based on the Köppen classification system modified by
Enriqueta Garcia for the climate conditions in Mexico. Cb (w1) (w): Cb indicates that the
climate is temperate; (w1) indicates sub-humid with fresh summer; (w) indicates the
presence of precipitation in summer. BS1kw (w): BS1 indicates that the climate is arid
climate; kw indicates semiarid-temperate with warm summer; (w) indicates the presence of
precipitation in summer. More details in Introduccion a la climatologia [Introducction to
climatology], retrieved January, 24th, 2014 form www.chapingo.mx/maizedb/ClimAgrop/
ClimasClasif.pdf
3)
The origin of the conservation land coincides with the 1980 General Plan of Urban
Development for the Federal District (Spanish: Plan Director de Desarrollo Urbano del
Distrito Federal). Aguilar et al. 6) notes that the General Plan was launched as a strategy
to control urbanization on the rural settings of Mexico City. The plan proposed two main
zones: 1) urban zone and 2) non-urban zone. The non-urban zone consisted of 1) the buffer
zone and 3) the preservation zone. The built up zone accommodated the urban setting; the
preservation zone contained the rural settings; the buffer zone worked as a transitional area,
between those two, separating urban from non-urban areas. The buffer zone was designed
to have a mixture of low-density urban land use and open spaces. The norms of land
occupation were applied through construction licenses, which specified the density and
construction area per plot. The permission for construction licenses was provided by city’s
authorities and only available to legal owners of properties. Here, it is when the policy
failed because many of the people come to possess the land by informal means. Aguilar
argued that the absence of actual land use controls to regulate the land market was one of
the main causes of the failure. He found that eventually different social groups obtained
legal or illegal appropriation of land in the buffer zone and the built up area expanded.
Aguilar concluded, among other things, that notwithstanding ambitions plans, the planning
framework in that time did not deal with the social pressures, especially from the poorer
groups. The preservation zone in the 1980 General Plan is today the conservation land.
4)
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Cities, 31, 438-443.
97
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106
Table I. Number of ahuejotes in the study units
Study
Study
Ahuejote
Study unit
unit
Borough
Ageb_ID
unit
tree
number
Borough
Ageb_ID
Study
Ahuejote
unit
number
surface
surface
tree
(ha)
(ha)
1
Tlahuac
110-7
184
60
9U
Xochimilco
1099
42
1017
2
Tlahuac
110-7
51
70
10U
Xochimilco
1101
72
2331
3
Tlahuac
110-7
115
27
11U
Xochimilco
1489
12
96
4
Tlahuac
110-7
39
22
5
Tlahuac
110-7
24
256
6
Tlahuac
110-7
27
209
7
Tlahuac
110-7
37
106
8
Tlahuac
110-7
22
459
9
Tlahuac
110-7
31
361
10
Tlahuac
110-7
29
479
11
Xochimilco
128-1
30
702
12
Xochimilco
128-1
33
1214
13
Xochimilco
128-1
24
772
14
Xochimilco
128-1
17
577
15
Xochimilco
128-1
39
527
16
Xochimilco
128-1
73
524
17
Xochimilco
128-1
17
631
18
Xochimilco
128-1
19
1086
19
Xochimilco
128-1
48
925
20
Xochimilco
128-1
16
445
21
Xochimilco
128-1
17
292
22
Xochimilco
128-1
45
532
23
Xochimilco
128-1
76
620
24
Xochimilco
128-1
67
373
25
Xochimilco
128-1
61
450
26
Xochimilco
128-1
44
233
27
Xochimilco
128-1
85
708
28
Xochimilco
128-1
11
461
29
Xochimilco
128-1
13
365
30
Xochimilco
128-1
21
222
31
Xochimilco
128-1
12
69
32
Xochimilco
128-1
34
141
33
Xochimilco
128-1
33
201
34
Xochimilco
128-1
28
511
35
Xochimilco
128-1
35
635
1U
Tlahuac
344
2
18
2U
Tlahuac
1427
3
14
3U
Xochimilco
52
6
73
4U
Xochimilco
90
90
2041
5U
Xochimilco
279
38
76
6U
Xochimilco
527
60
299
7U
Xochimilco
688
13
222
8U
Xochimilco
724
0
107
Table II. Features of water units types in the rural area in chinampas
1
Tlahuac
110-7
181
184
2
Tlahuac
110-7
43
51
3
Tlahuac
110-7
41
93
4
Tlahuac
110-7
30
39
5
Tlahuac
110-7
36
24
6
Tlahuac
110-7
15
27
7
Tlahuac
110-7
6
37
8
Tlahuac
110-7
27
22
9
Tlahuac
110-7
10
31
10
Tlahuac
110-7
12
29
11
Xochimilco
128-1
25
30
12
Xochimilco
128-1
39
33
13
Xochimilco
128-1
24
24
14
Xochimilco
128-1
17
17
15
Xochimilco
128-1
31
39
16
Xochimilco
128-1
19
73
17
Xochimilco
128-1
16
17
18
Xochimilco
128-1
18
19
19
Xochimilco
128-1
22
48
20
Xochimilco
128-1
21
16
21
Xochimilco
128-1
26
17
22
Xochimilco
128-1
18
45
23
Xochimilco
128-1
30
76
24
Xochimilco
128-1
30
67
25
Xochimilco
128-1
25
61
26
Xochimilco
128-1
20
44
27
Xochimilco
128-1
101
85
28
Xochimilco
128-1
24
11
29
Xochimilco
128-1
21
13
30
Xochimilco
128-1
13
21
31
Xochimilco
128-1
8
12
32
Xochimilco
128-1
47
34
33
Xochimilco
128-1
68
33
34
Xochimilco
128-1
43
28
35
Xochimilco
128-1
43
35
Water conditions
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
Water
units
types
Irrigation
system
other
Study
unit
surface
(ha)
Floods
Number
of
holdings
by study
unit
Wetland
Ageb_ID
Lake
Borough
Canals
Study unit
number
●
●
IX
IX
VIII
●
IX
I
I
I
I
I
I
I
I
I
I
●
I
●
V
I
I
I
I
●
●
●
●
●
●
●
●
I
●
●
●
III
VII
VII
IV
●
VI
II
I
I
I
I
I
I
I
I
Note: ● indicates the presence of the aspect
108
Table III. Features of water units types in the urban area in chinampas
52
4U
90
5U
279
6U
527
7U
688
8U
724
9U
1099
10U
1101
11U
1489
●
●
●
●
●
●
●
●
Water
units types
other
1427
3U
Irrigation system
2U
Floods
344
Wetland
1U
Water conditions
Lake
Ageb_ID
Canals
Unit
Number
●
IX
I
I
I
I
I
●
I
IX
I
●
I
IX
Note: ● indicates the presence of the aspect
109
Table-IV Farm characteristics in study units in rural area in chinampas
Study
unit
number
Borough
Ageb_ID
Number
of farm
holdings
by unit
Study
unit
surface
(ha)
Number of
agricultural
holdings
Number
of animal
production
holdings
Number
of
forestry
and
logging
holdings
1
Tlahuac
110-7
181
184.00
140
41
0
2
3
Tlahuac
Tlahuac
110-7
110-7
43
41
51.00
93.00
36
33
7
8
0
0
4
5
Tlahuac
Tlahuac
110-7
110-7
30
36
39.00
24.00
25
31
5
5
0
0
6
7
Tlahuac
Tlahuac
110-7
110-7
15
6
27.00
37.00
12
3
3
3
0
0
8
9
Tlahuac
Tlahuac
110-7
110-7
27
10
22.00
31.00
22
5
5
5
0
0
10
11
Tlahuac
Xochimilco
110-7
128-1
12
25
29.00
30.00
9
21
3
4
0
0
12
13
Xochimilco
Xochimilco
128-1
128-1
39
24
33.00
24.00
27
20
12
4
0
0
14
15
Xochimilco
Xochimilco
128-1
128-1
17
31
17.00
39.00
13
26
4
5
0
0
16
17
Xochimilco
Xochimilco
128-1
128-1
19
16
73.00
17.00
14
12
5
4
0
0
18
19
Xochimilco
Xochimilco
128-1
128-1
18
22
19.00
48.00
14
19
4
3
0
0
20
21
Xochimilco
Xochimilco
128-1
128-1
21
26
16.00
17.00
18
23
3
3
0
0
22
23
Xochimilco
Xochimilco
128-1
128-1
18
30
45.00
76.00
17
24
1
6
0
0
24
25
Xochimilco
Xochimilco
128-1
128-1
30
25
67.00
61.00
22
22
8
3
0
0
26
27
Xochimilco
Xochimilco
128-1
128-1
20
101
44.00
85.00
18
98
2
3
0
0
28
29
Xochimilco
Xochimilco
128-1
128-1
24
21
11.00
13.00
21
18
3
3
0
0
30
31
Xochimilco
Xochimilco
128-1
128-1
13
8
21.00
12.00
10
5
3
3
0
0
32
33
Xochimilco
Xochimilco
128-1
128-1
47
68
34.00
33.00
44
64
3
4
0
0
34
35
Xochimilco
Xochimilco
128-1
128-1
43
43
28.00
35.00
41
41
2
2
0
0
110
Table-V Chinampero characteristics relating to study units in rural area in
chinampas
Number of farm holdings by
study unit
Agricultural holdings by
study unit
1 to 2 persons
3 to 5 persons
6 to 10 persons
11 to 30 persons
31 to 50 persons
51 person and more
Tlahuac Borough
Xochimilco Borough
Other Borough
Total of chinamperos
110-7
184
181
140
24
84
32
0
0
0
140
0
0
628
2
110-7
51
43
36
11
16
7
2
0
0
36
0
0
177.5
3
110-7
93
41
33
13
12
8
0
0
0
32
0
1
131.5
4
110-7
39
30
25
5
14
3
3
0
0
25
0
0
149
110-7
24
36
31
9
12
7
3
0
0
31
0
0
179
110-7
27
15
12
6
6
0
0
0
0
12
0
0
33
7
110-7
37
6
3
1
2
0
0
0
0
2
1
0
9.5
8
110-7
22
27
22
6
13
3
0
0
0
22
0
0
85
9
10
110-7
110-7
31
29
10
12
5
9
0
5
0
4
5
0
0
0
0
0
0
0
5
9
0
0
0
0
40
23.5
11
128-1
30
25
21
13
5
3
0
0
0
0
21
0
63.5
12
128-1
33
39
27
14
8
5
0
0
0
0
27
0
93
13
128-1
24
24
20
7
10
3
0
0
0
1
19
0
74.5
14
128-1
17
17
13
6
5
2
0
0
0
0
12
1
45
15
128-1
39
31
26
14
6
5
1
0
0
0
26
0
105.5
16
128-1
73
19
14
10
2
2
0
0
0
0
13
1
39
17
128-1
17
16
12
7
2
2
1
0
0
0
12
0
55
18
128-1
19
18
14
6
4
3
1
0
0
0
14
0
69.5
19
128-1
48
22
19
7
7
3
1
1
0
0
19
0
123.5
20
128-1
16
21
18
6
9
3
0
0
0
0
18
0
69
21
128-1
17
26
23
12
7
4
0
0
0
0
23
0
78
128-1
45
18
17
9
6
2
0
0
0
0
17
0
53.5
128-1
76
30
24
7
13
4
0
0
0
0
24
0
94.5
128-1
67
30
22
8
8
3
2
1
0
0
22
0
149.5
25
128-1
61
25
22
2
13
5
2
0
0
0
22
0
136
26
128-1
44
20
18
4
11
3
0
0
0
0
18
0
74
27
128-1
85
101
98
40
27
21
10
0
0
0
98
0
541
28
128-1
11
24
21
11
6
3
1
0
0
0
21
0
85
29
128-1
13
21
18
7
10
1
0
0
0
0
18
0
58.5
30
128-1
21
13
10
4
3
3
0
0
0
0
10
0
42
31
128-1
12
8
5
4
1
0
0
0
0
0
5
0
10
32
128-1
34
47
44
10
25
9
0
0
0
0
44
0
187
33
128-1
33
68
64
20
32
9
3
0
0
0
64
0
291.5
34
128-1
28
43
41
11
19
9
1
1
0
0
41
0
225.5
35
128-1
35
43
41
12
15
13
1
0
0
0
41
0
202.5
22
23
24
Tlahuac
6
Xochimilco
5
Borough
1
Study unit number
Study unit surface (ha)
Person's
borough origin
Ageb_ID
Categories by number of persons
occupied in agriculture by study unit
111
Table-VI Characteristics of study units by types of plants and agricultural
Fruit and tree nut holdings
Floriculture holdings
Other
Bean grain holdings
Grain maize holdings
Forage maize holdings
126
13
1
0
0
16
0
70
0
36
33
32
22
1
5
0
1
3
5
0
0
0
0
0
0
32
20
0
0
4
5
110-7
110-7
30
36
39
24
25
31
25
27
0
2
0
1
0
1
0
0
0
0
0
0
22
27
0
0
110-7
110-7
15
6
27
37
12
3
9
2
1
1
1
0
1
0
0
0
0
0
0
0
9
2
0
0
8
9
110-7
110-7
27
10
22
31
22
5
22
3
0
1
0
0
0
1
0
0
0
0
0
0
22
3
0
0
10
11
110-7
128-1
12
25
29
30
9
21
4
8
5
9
0
0
0
4
0
0
0
0
1
1
3
7
0
0
12
13
128-1
128-1
39
24
33
24
27
20
13
10
10
10
0
0
4
0
0
0
1
2
1
0
11
8
0
0
14
15
128-1
128-1
17
31
17
39
13
26
7
13
4
8
1
0
1
5
0
0
0
0
0
0
7
13
0
0
16
17
128-1
128-1
19
16
73
17
14
12
7
5
4
6
0
0
2
1
1
0
0
0
0
0
7
5
0
0
18
19
128-1
128-1
18
22
19
48
14
19
4
12
7
5
1
2
2
0
0
0
0
0
0
0
4
12
0
0
20
21
128-1
128-1
21
26
16
17
18
23
11
16
4
6
0
0
3
1
0
0
0
0
0
0
11
15
0
1
128-1
128-1
18
30
45
76
17
24
7
5
2
8
0
0
7
11
1
0
0
0
0
0
7
5
0
0
128-1
128-1
30
25
67
61
22
22
0
0
17
20
0
0
5
2
0
0
0
0
0
0
0
0
0
0
26
27
128-1
128-1
20
101
44
85
18
98
0
3
16
16
0
0
2
79
0
0
0
0
0
0
0
3
0
0
28
29
128-1
128-1
24
21
11
13
21
18
9
9
4
3
0
0
8
6
0
0
0
0
0
0
9
9
0
0
30
31
128-1
128-1
13
8
21
12
10
5
5
0
0
0
0
0
5
5
0
0
0
0
0
0
5
0
0
0
32
33
128-1
128-1
47
68
34
33
44
64
4
0
28
59
0
0
12
4
0
1
0
0
0
0
4
0
0
0
34
35
128-1
128-1
43
43
28
35
41
41
2
0
38
31
0
0
1
10
0
0
0
0
0
0
2
0
0
0
22
23
24
25
Tlahuac
Xochimilco
6
7
crop
Vegetable
All other leguminous
grains holdings
Grain holdings
140
51
93
holdings
Agricultural holdings
184
43
41
holdings
Study unit surface (ha)
181
110-7
110-7
Ageb _ID
110-7
2
3
Borough
1
Study unit number
Number of farm holdings
by study unit
methods in the rural area in chinampas
…to be continued in next page
112
Study unit number
Barely grain holdings
Forage sorghum holdings
Forage oats holdings
Tomato (red tomato) holdings
Green chili holdings
Tomato (green tomato) holdings
Pumpkin holdings
Other vegetables crops holdings
Café groves holdings
Avocado groves holdings
Apple groves holdings
Non-citrus fruit and tree nut farming
holdings
Foods crops grown in greenhouses
holdings
Open-sky floriculture holdings
Floriculture under greenhouse holdings
Tree production holdings
All other non-food crops under holdings
Pasture holdings
All other crop farming holdings
…comes from previous page
1
3
0
37
2
1
1
5
4
0
0
1
0
0
0
0
0
0
0
0
2
3
0
0
0
0
0
2
0
0
0
0
0
0
0
1
1
4
0
0
0
0
0
0
0
1
1
1
0
1
2
3
0
0
0
0
0
0
0
0
4
5
0
0
0
0
3
0
0
0
0
0
0
0
0
0
0
2
0
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
6
7
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
8
9
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
10
11
0
0
0
0
0
0
0
0
0
0
0
0
0
2
5
7
0
0
0
0
0
0
0
0
0
0
0
2
0
1
0
0
0
1
0
0
0
0
12
13
0
0
0
0
0
0
1
2
0
0
0
0
1
2
8
6
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
2
0
0
0
0
0
14
15
0
0
0
0
0
0
0
1
0
0
0
0
2
0
2
7
0
0
1
0
0
0
0
0
0
0
1
3
0
2
0
0
0
0
0
0
0
0
16
17
0
0
0
0
0
0
1
0
0
0
0
0
0
1
3
5
0
0
0
0
0
0
0
0
0
1
0
0
2
0
0
0
0
0
1
0
0
0
18
19
0
0
0
0
0
0
1
1
0
0
0
0
0
0
6
4
0
1
0
0
0
0
1
1
1
0
0
0
1
0
0
0
0
0
0
0
0
0
20
21
0
0
0
0
0
0
0
1
0
0
0
0
0
0
4
5
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
2
0
0
0
0
0
22
23
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
8
0
0
0
0
0
0
0
0
0
0
0
0
5
8
0
2
2
1
0
0
1
0
24
25
0
0
0
0
0
0
0
0
0
0
0
0
0
0
17
20
0
0
0
0
0
0
0
0
1
0
0
1
4
1
0
0
0
0
0
0
0
0
26
27
0
0
0
0
0
0
0
0
0
0
0
0
0
1
16
15
0
0
0
0
0
0
0
0
1
15
0
1
1
59
0
0
0
4
0
0
0
0
28
29
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4
3
0
0
0
0
0
0
0
0
0
0
0
4
4
0
0
1
4
1
0
0
0
0
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
0
0
5
2
0
0
0
0
32
33
0
0
0
0
0
0
0
0
0
0
0
0
1
0
27
59
0
0
0
0
0
0
0
0
0
1
0
0
9
3
0
0
3
0
0
0
0
1
34
35
0
0
0
0
0
0
0
0
0
0
0
0
0
0
38
31
0
0
0
0
0
0
0
0
0
2
0
0
1
7
0
0
0
1
0
0
0
0
113
Table-VII Chinampero characteristics relating to study units in the urban area in
chinampas
Study
units
number
Borough
Ageb_ID
Study surface
(ha)
Population
Number of
houses
Number of houses
with drain
connection
1u
Tlahuac
0344
2
20
9
5
2u
Tlahuac
1427
3
391
91
83
3u
Xochimilco
0052
6
130
36
26
4u
Xochimilco
0090
90
4,348
1143
965
5u
Xochimilco
0279
38
1385
369
306
6u
Xochimilco
0527
60
2071
540
445
7u
Xochimilco
688
13
310
80
68
8u
Xochimilco
0724
26
567
130
101
9u
Xochimilco
1099
42
2439
591
534
10u
Xochimilco
1101
72
2438
618
490
11u
Xochimilco
1489
12
421
107
70
12u
Tlahuac
1395
54
1377
400
321
114
Acknowledgement
I wish to express my deepest gratitude to my advisor Professor Hiroyuki Kanekiyo for his
full support, expert guidance and encouragement throughout my studies and research. I will be
always grateful for his trust in me. Without his incredible patience and timely counsel, my thesis
work would have been a frustrating pursuit. I also express my appreciation to the Associate
Professor Masakazu Tani and Associate Professor Azahiro Kazuo for having served on my
committee thesis. Their thoughtful questions were always valued greatly.
I also thank my family. My parents have given me lots of support. I would not have been
able to complete this thesis without your love. Maruquita and Abelito, I want to say thanks for
being inspiring persons for me. To my brothers Jahaziel and Zury, I want to thank them for their
unceasing encouragement and support. I take this opportunity to dedicate this work to my dear
aunt Rosa, I hope we will meet again someday.
Special thanks to my amigo Etienne Garcia. I always will be grateful for his help and smart
comments on this work.
I also place on record, my sense of gratitude to one and all who, direct or indirectly, have
lent their help to me in this venture.
February, 2014
Jairo Agustin Reyes Plata
115