almendros y corales

Faculty of Forest, Geo and Hydro Sciences: Institute of Forest Growth and Forest Computer Sciences
The effect of site selection on the growth of
Dipteryx panamensis
in timber plantations in Costa Rica and Panama
by
Fabian Schmidt
A thesis submitted in partial fulfillment of the requirements for the degree
Master of Science in Tropical Forestry and Management
Faculty of Forest, Geo and Hydro Sciences University of Technology, Dresden, Germany
Date of Submission:
30. September 2009
Scientific supervisor:
Prof. Dr. rer. silv. habil. Heinz Röhle
Institute of Forest Growth and Forest Computer Sciences
University of Technology, Dresden, Germany
Co-supervisor:
Dr. rer. silv. Hubertus Pohris
Institute of International Forestry and Forest Products
University Technology, Dresden, Germany
Local advisor:
Dr. Olman Murillo
Instituto Tecnológico de Costa Rica, Cartago, Costa Rica
Lending admitted / not admitted
Dresden, September 2009
TABLE OF CONTENTS
TABLE OF CONTENTS
TABLE OF CONTENTS ............................................................................................................ i
ABSTRACT ...........................................................................................................................iv
ACKNOWLEDGEMENTS ....................................................................................................... v
LIST OF ABBREVIATIONS .....................................................................................................vi
LIST OF FIGURES .................................................................................................................vii
LIST OF TABLES ................................................................................................................. viii
LIST OF EQUATIONS ............................................................................................................ix
1.
INTRODUCTION ..................................................................................................... 10
1.1
Research justification ................................................................................................ 11
1.2
Research objectives ................................................................................................... 12
1.3
Research questions .................................................................................................... 13
2.
LITERATURE REVIEW .............................................................................................. 14
2.1
Species information ................................................................................................... 14
2.2
Almendro in timber plantations ................................................................................ 16
2.3
Agroforestry and carbon forestry using Almendro ................................................... 19
3.
METHODOLOGY ..................................................................................................... 21
3.1
Study area .................................................................................................................. 21
3.2
Description of the sample plots................................................................................. 22
3.3
Data collection ........................................................................................................... 23
3.4
Data analysis .............................................................................................................. 24
3.5
Growth modeling ....................................................................................................... 28
3.6
Stand height curves ................................................................................................... 29
3.7
Site classification ....................................................................................................... 31
4.
RESULTS ................................................................................................................. 33
4.1
Growth of Almendro in Costa Rica and Panama ....................................................... 33
4.1.1 Site group 1, CR .................................................................................................. 33
4.1.2 Site group 2, CR .................................................................................................. 34
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TABLE OF CONTENTS
4.1.3 Site group 3, CR .................................................................................................. 35
4.1.4 Site group 4, CR .................................................................................................. 38
4.1.5 Site group 5, CR .................................................................................................. 42
4.1.6 Site group 6, CR .................................................................................................. 44
4.1.7 Site group 7, PA .................................................................................................. 46
4.1.8 Site group 8, PA .................................................................................................. 50
4.1.9 Site group 9, PA .................................................................................................. 52
4.2
Stand characteristics of Almendro plantations ......................................................... 53
4.2.1 Stem diameter distribution ................................................................................ 54
4.2.2 Stand height curves ............................................................................................ 56
4.3
Growth dynamics of Almendro ................................................................................. 58
4.3.1 Mean annual increment of Almendro................................................................ 59
4.3.2 Top height growth .............................................................................................. 60
4.4
Preliminary site indices for Almendro ....................................................................... 61
4.5
Top-height projections .............................................................................................. 63
5.
DISCUSSION ........................................................................................................... 66
5.1
Data basis................................................................................................................... 66
5.2
The effect of site selection ........................................................................................ 68
5.2.1 Site index calculation and top height projection ............................................... 70
5.2.2 Frequency of site index classes .......................................................................... 71
5.2.3 Promising regions for Almendro plantations ..................................................... 73
5.3
Silviculture ................................................................................................................. 73
5.3.1 Initial spacing and stand density ........................................................................ 74
5.3.2 Thinning and pruning ......................................................................................... 75
5.4
Timber production on Almendro plantations ........................................................... 77
5.5
Carbon forestry .......................................................................................................... 79
ii
TABLE OF CONTENTS
6.
5.6
Agroforestry ............................................................................................................... 81
5.7
Limitations of the present study ............................................................................... 83
5.8
Recommendations ..................................................................................................... 83
CONCLUSION ......................................................................................................... 84
BIBLIOGRAPHY .................................................................................................................. 85
APPENDICES...................................................................................................................... 94
Appendix 1 - Detailed information on sampled Almendro plantations ............................... 94
Appendix 2 - Stand diameter distribution ............................................................................ 95
Appendix 3 - Stand height curves......................................................................................... 98
Appendix 4 - Estimated Parameter values ......................................................................... 102
Appendix 5 - Photos ........................................................................................................... 104
EIDESSTATTLICHE ERKLÄRUNG.........................................................................................108
iii
ABSTRACT
ABSTRACT
Plantation forestry is of high importance in both Central American countries, Costa Rica and
Panama, who promote the establishment of timber plantations through government
incentive programs. While most plantation companies plant exotic tree species such as Teak
(Tectona grandis), local farmers tend to prefer native species, which are often better
adapted to low intensity management and poor soils. More and more companies also start
to diversify their product portfolios by using native species. The potential of native tree
species is enormous, but research is often site-specific and little is known regarding their
long term performance on timber plantations. This lacking knowledge about the silviculture
and performance on a multitude of sites, endangers the future of native tree species in
timber plantations.
One very promising native tree species that is planted across Costa Rica and Panama is
Almendro (Dipteryx panamensis), a keystone rainforest species and premium hardwood on
local timber markets. To address the research questions how the species develops over time,
how the site affects the growths and to identify promising regions for Almendro plantations,
growth records from 36 plantations, some of which have been agroforestry systems, were
collected and analyzed. Developments and stand characteristics of all plantations were
described and differences between climate zones became evident.
Performance in the Atlantic lowlands of Costa Rica was the greatest and high rainfalls, lower
elevations and soils with good drainage favor the growth of Almendro, whereas the growth
was restricted in dry climates, elevations higher 500 m and on poorly drained soils.
A preliminary site classification was developed, using five site index classes to describe the
growth of Almendro on different sites and a specific top height growth model was designed
for several plantations to validate these trends. Additionally, provisional recommendations
for silvicultural treatments were given and the potential of Almendro for carbon forestry and
agroforestry systems was assessed.
iv
ACKNOWLEDGEMENTS
ACKNOWLEDGEMENTS
First of all, I want to thank my supervisors Prof. Dr. Heinz Röhle and Dr. Pohris from the
University of Technology Dresden, Germany for their guidance and support from the early
ideas until the final thesis. Dr. Olman Murillo from the Instituto Tecnológico de Costa Rica in
Cartago has guided me through the Costa Rican world of forestry, which I’m more than
grateful for. The passion for Almendro connected us from the moment we first met and I still
remember our fruitful discussions about native species research and tropical forestry in
general. I would like to express my sincere gratitude to Dr. Klaus Römisch for his patient
assistance and comments about statistics, growth modeling and site classification, and Luis
Ugalde for his professional suggestions and training in MIRASILV.
During my quest for Almendro plantations in Costa Rica and Panama many people crossed
my way and I am so grateful for their practical support, technical inputs, suggestions and
encouragement. Without them, this thesis would never have been possible. As this thesis
made use of information that was generated by many plantations owners and scientists
across Costa Rica and Panama, they receive my utmost appreciation. In Costa Rica,
particularly to Adrian Delgado (Precious Woods), Rolando Camacho, Herster Barres (RTT),
Guillermo Navarro, Tamara Benjamin, Marvin Hernandez, Oscar Sanabria (CATIE), Orlando
Vargas, Ronald Vargas, Bérnal Matarrita, Deedra McClearn (OTS – La Selva), Daniel Piotto,
Florencia Montagnini (Yale University), Carlos Sandi, Raul Paniaqua, Ricardo Russo (EARTH),
Juan Pablo Jaramillo Castaño (Los Tucanes). In Panama to Jefferson Hall, Michiel Van Breugel
(PRORENA) and all my colleagues from ForestFinance, especially Yaels Camacho.
I am indebted to Dr. Marvin Castillo, Andres Castillo and Silke Berger for their valuable field
assistance. Finally, I want announce my greatest respect to Lucia Rodriguez (ITCR) for waking
my passion for native tree species research when I first worked in Costa Rica in 2007.
Financial support from the “DAAD - Deutscher Akademischer Austausch Dienst” and logistic
support from ForestFinance is gratefully acknowledged.
v
LIST OF ABBREVIATIONS
LIST OF ABBREVIATIONS
AGCL
Age class
CATIE
Centro Agronómico Tropical de Investigación y Enseñanza
CFS
CarbonFix Standard
CITES
Convention on International Trade in Endangered Species of Wild
Fauna and Flora
CO2
Carbon dioxide
COSEFORMA
Cooperación en los Sectores Forestales y Maderero
CR
Costa Rica
DBH
Diameter at breast height
EARTH
Esucela de agricultura de la region tropical humeda
ITCR
Instituto Tecnológico de Costa Rica
MAI
Mean annual increment
MINAE
Ministerio de Ambiente y Energia (Costa Rican ministry of environment
and energy)
m.a.s.l
Meters above sea level
OTS
Organization for Tropical Studies
PA
Panama
PRORENA
Proyecto de Reforestación con Especies Nativas
RTT
Reforest the tropics Inc.
SHC
Stand height curve
SI
Site index
SIGR
Site group
vi
LIST OF FIGURES
LIST OF FIGURES
Figure 1: Map of the study area ............................................................................................... 22
Figure 2: Stand diameter distribution in “Santa Cecilla” ......................................................... 54
Figure 3: Stand diameter distribution in “Buenos Aires” ........................................................ 55
Figure 4: Stand diameter distribution in “La Bomba”.............................................................. 55
Figure 5: Stand diameter distribution on the “Canadian Trial” ............................................... 56
Figure 6: Fitted Michailoff stand height curves. “Cope San Juan”........................................... 57
Figure 7: Fitted Michailoff stand height curve and observed values. “Canadian Trial” .......... 57
Figure 8: Fitted Michailoff stand height curve for D. panamensis in “San Juan” in a mixed
species plot together with A. hunsteini, E. deglupta and S. macrophylla........................ 58
Figure 9: MAI in top height (h50) of D. panamensis in timber plantations .............................. 59
Figure 10: MAI in top diameter (d50) of D. panamensis in timber plantations ........................ 60
Figure 11: Top height development of D. panamensis over age ............................................. 61
Figure 12: Site index curves for 5 different site qualities in CR and PA ................................... 63
Figure 13: Top height growth projection in comparison with site index curves ..................... 65
Figure 14: Fitted Michailoff stand height curves for D. panamensis, “Pampanillo” ............. 101
vii
LIST OF TABLES
LIST OF TABLES
Table 1: List of own measurements and data sources for growth data prior 2009 ................ 24
Table 2: List of age classes, their ranges and frequencies ....................................................... 25
Table 3: List of site groups and their attributes. ...................................................................... 25
Table 4: Growth of Almendro in SIGR 1 ................................................................................... 34
Table 5: Growth of Almendro in SIGR 2 ................................................................................... 35
Table 6: Growth of Almendro in SIGR 3, AGCL 3 ..................................................................... 36
Table 7: Growth of Almendro in SIGR 3, AGCL 3 ..................................................................... 38
Table 8: Growth of Almendro at “La Selva”, SIGR 4, AGCL 3 ................................................... 40
Table 9: Growth of Almendro for “EARTH” and “Los Tucanes”, SIGR 4, AGCL 2 and 3 ........... 42
Table 10: Description of the species mixtures on “Hacienda Las Delicias”, SIGR 4................. 43
Table 11: Growth of Almendro in SIGR 5, AGCL 2 and 3 ......................................................... 44
Table 12: Description of the species mixtures in “Mulas” and “San Juan”, SIGR 6. ................ 45
Table 13: Growth of Almendro in SIGR 6, AGCL 2 ................................................................... 46
Table 14: Growth of Almendro on the PRORENA plots “Las Lajas “, SIGR 7, AGCL 1 .............. 47
Table 15: Growth of Almendro on the PRORENA plots “Liquid Jungle Lab “, SIGR 7, AGCL 1 48
Table 16: Growth of Almendro on the ForestFinance plantations, SIGR 7, AGCL 2 ................ 49
Table 17: Growth of Almendro in “Los Santos”, SIGR 8, AGCL 1 ............................................. 51
Table 18: Growth of Almendro in “Rio Hato”, SIGR 8, AGCL 1 ................................................ 52
Table 19: Growth of Almendro in SIGR 9, AGLC 1 ................................................................... 53
Table 20: Cross table with the number of available growth records at certain age ............... 67
Table 21: Frequency of site index classes and age classes in each site group ........................ 72
Table 22: Proposed thinning regime for Almendro in timber plantations .............................. 78
Table 23: Overview and characteristics of Almendro plantations in Costa Rica ..................... 95
Table 24: Overview and characteristics of Almendro plantations in Panama......................... 95
viii
LIST OF EQUATIONS
LIST OF EQUATIONS
Equation 1: Volume calculation ............................................................................................... 27
Equation 2: Basal area calculation ........................................................................................... 27
Equation 3: Chapman - Richards function ............................................................................... 29
Equation 4: Petterson - height curve function ........................................................................ 30
Equation 5: Michailoff - height curve function ........................................................................ 30
Equation 6: CarbonFix equation .............................................................................................. 80
ix
INTRODUCTION
1. INTRODUCTION
Forest scientists worldwide recommend the use of native tree species for reforestation- and
restoration projects. It is said that native tree species generally have better site adaption,
better survival rates and fewer pests. They are also better adapted to low input forestry that
is often practiced by local farmers, in contrast to exotic species, which require more
intensive production systems and are regularly used by reforestation companies (Butterfield
and Fisher, 1994; Butterfield, 1995; Haggar et al., 1998; Jiménez et al., 2002).
The immense biodiversity of native tree species especially in Central America provides a
resource to fill other production niches if a wider range of production systems is considered
such as agroforestry, mixed plantations or fuel wood lots (Wishnie et al., 2007). However,
relatively little information exists regarding the performance of these native trees on timber
plantations and as a result this knowledge gap still hinders the implementation in
reforestation schemes, for both famers and companies, on a larger scale.
Usually exotic species are preferred because of existing markets, good seed availability and
better scientific knowledge about the growth and management of these species (Butterfield
and Fisher, 1994; Butterfield, 1995). Likewise, forestry in Costa Rica and Panama is
dominated by the use of exotic species such as Teak (Tectona grandis) or Melina (Gmelina
arborea). Fortunately, research institutes in Costa Rica like the “Instituto Tecnológico de
Costa Rica” (ITCR), the “Centro Agronómico Tropical de Investigación y Enseñanza” (CATIE),
the “Esucela de agricultura de la region tropical humeda” (EARTH) or projects like the
“Proyecto de Reforestación con Especies Nativas” (PRORENA) in Panama, have been
studying a variety of promising tree species native to Central America.
For some native tree species such as Pilon/Zapatero (Hyeronima alchorneoides), Roble
Coral/Amarillo (Terminalia amazonia) or Pochote/Cedro espino (Bombacopsis quinata)
research is quite advanced and publications are available.
10
INTRODUCTION
As a result, forest management schemes were developed for these species, which facilitates
their use on timber plantations.
1.1 Research justification
The variety of native tree species is enormous due to the vast biodiversity in tropical
countries, yet little is known about some very promising trees or research outcomes are very
site specific (Butterfield and Fisher, 1994; Butterfield, 1995; Haggar et al., 1998; Aguilar and
Condit, 2001; Piotto et al., 2003; Wishnie et al., 2007).
One of these “unknown” species is Almendro (Dipteryx panamensis), which was selected for
this research for several reasons. The valuable timber is very dense and resistant to decay, it
also captures a high amount of carbon dioxide in the tree´s biomass (Redondo-Brenes and
Montagnini, 2006; Redondo-Brenes, 2007). In addition Almendro plays a vital role in
Neotropical ecosystems as an keystone species that provides food and shelter to
endangered species and other forest fauna (Bonaccorso et al., 1980; Flores, 1992; MongeArias et al., 2003).
Almendro holds great potential for the production of valuable timber on timber plantations
and the reduction of green house gases in the atmosphere, while contributing to biodiversity
protection and in the best scenario even reduced deforestation. This species has been
studied since the beginning of native tree species research in Costa Rica and Panama. Over
the past 25 years experience has been gathered on sample plots in natural forests and
scientific plantations. Nevertheless, most studies regarding the performances of Almendro
on plantations have been conducted within a relatively small geographic range, thus making
it difficult to extrapolate the results to areas with different climates.
This study will connect research that had formerly been limited to a small geographic range,
to derive growth predictions, which are valid for most parts of Costa Rica and Panama. These
finding can help to secure and increase the income from Almendro timber plantations
through improved forest management practices, while the general promotion of the species
11
INTRODUCTION
Almendro might stimulate the establishment of new Almendro plantations thus relieving
some pressure from natural old growth forests. Many plantations have been established by
local farmers who dedicated small portions of their farms to plantation forestry with mostly
native species (Haggar et al., 1998; Piotto et al., 2003; Streed et al., 2006). The majority of
farmers did not receive any training in intensive plantation forestry and knowledge about
the best management is lacking for native tree species, such as Almendro. Gathering data
about long-term performance of Almendro under varying management regimes is necessary
to reduce investments risk for farmers and other plantation owners (Piotto et al., 2003).
Through the development of a site classification, using site indices, based on data from plots
in both Costa Rica and Panama, forest managers will be able to classify and project stand
growth of their Almendro plantations.
It is likely that in the long run the demand for tropical hardwood produced on plantations,
will exceed supply and thus tropical hardwood plantations will have to produce an increasing
volume during the coming decades. If the good market potential is not realized the
opportunity to substitute wood and non-wood products will be lost (Varmola and Carle,
2002), but through proper site-classification and the development of forest management
schemes the wood production of timber plantations can be optimized.
To realize the potential of timber plantations, it is of highest importance to know as much as
possible about the commercial tree species. Consequently, studying how species like
Almendro perform on a multitude of sites is the next logical step in the ongoing
development of tropical forestry.
1.2 Research objectives
From numerous sites in Costa Rica and Panama data on actual tree growth was measured
and carried together to see if and how site selection of Almendro plantations influences the
growth performance. In both countries past measurements were kindly provided from
plantation owners and subsequently analyzed.
12
INTRODUCTION
As past and present research outcomes had been mainly valid for a small geographic range,
primarily the Atlantic lowlands of Costa Rica (Wishnie et al., 2007), the creation of time
series of the growth of Almendro for different climates based on own measurements and
existing, sometimes unpublished datasets, is the main objective of this study.
From these findings a site classification is developed through site index curves. Wherever
possible, growth projections will be developed using predictive modeling techniques and
finally, silvicultural regimes and possible yield of mature Almendro will be discussed together
with the species´ potential for production systems, such as carbon forestry and agroforestry.
1.3 Research questions
-
How does Almendro develop over time?
-
How does the site affect the growth of Almendro?
-
Which are the most suitable regions for Almendro plantations?
13
LITERATURE REVIEW
2. LITERATURE REVIEW
2.1 Species information
Almendro (Dipteryx panamensis) is a large canopy-emergent tree and rainforest keystone
species that occurs from Nicaragua to Colombia in the tropical wet- and moist forests all
along the Atlantic coast (Flores, 1992). The species belongs to the family Fabaceae
(Leguminosae), sub-family Papilionoidae and is internationally known as “Almendro” or
“Tonka Bean tree”. Local names are diverse and depend on the region, although “Almendro”
is the most common name (Costa Rica, Nicaragua, Panama, and Colombia). Other names
include “Almendro de montaña” (Northern Atlantic zone of Costa Rica, Panama), “Almendro
amarillo”, “Almendrón” and “Eboe” (Bribri; indigenous tribe in Costa Rica). This species is
also referred to as Coumarouna panamensis Pitt., Dipteryx oleiforma Benth. as well as
Oleiocarpon panamensis (Pittier) Dweyer (Vozzo, 2002; Cordero et al., 2003).
The species naturally exists along a precipitation- and temperature gradient from
24°C to 30 °C in mean annual temperature and 3500 – 5500 mm mean annual rainfall (Vozzo,
2002, COSEFORMA, 1999), while the vertical distribution ranges from 20 – 500 m.a.s.l
(Jiménez et al., 2002; Cordero et al., 2003).
Canopy-emergent trees like Almendro frequently appear in densities less than 1 adult tree
per hectare (Clark and Clark, 1987; Hanson et al., 2006; Hanson et al., 2008). Some regions
however support higher densities like the border region of Costa Rica and Nicaragua where
densities approach 2 adult trees per hectare (Chun, 2008), or parts of the “Corredor
biológico Río San Juan-Estación Biológica La Selva“, with the highest density ever recorded of
4 trees per hectare (Chaverri and López, 1998).
Almendro naturally grows on alluvial or sandy soils and occasionally on soils with an acid and
clay profile (Flores, 1992) with pH-values ranging from 4 to 5.5 (Vidal-Riveros, 2004).
14
LITERATURE REVIEW
Environmental conditions that support high densities of Almendro appear to be soils of the
Humult, Aquent, and Tropept‐Aquept sub-order (Chun, 2008).
The height of Almendro trees can reach a maximum of 50 m and diameters of up to 1.5 m.
Individuals may live close to 300 years with a theoretical maximum age of 654 years, as
found by Fichtler et al. (2003) based on 14C dating and tree ring counts.
Almendro trees have vertical lenticels on their reddish-brown and smooth bark and the stem
develops ample basal roots, but seldom buttresses. Branches are ascendant and the crown is
semispherical, consisting of alternate, pinnated leaves with 10 to 20 stippled leaflets,
opposite, and sub-opposite alternative (Flores, 1992; COSEFORMA, 1999; Jiménez et al.,
2002). Bright purple flowers appear with the beginning of the rainy season in late May and
flowering lasts until late August, with peak blooming occurring in mid
‐July
(Perry and
Starrett, 1980), although these blooming patterns vary among regions (Arnáez and Moreira,
1995). Immature fruits are green and turn brownish when ripe. The fruits are pods 6 to 8 cm
long, 4 to 5 cm wide, and 2 to 3 cm thick, encapsulating seeds ranging from 4.5 to 6 cm long,
3 to 3.5 cm wide, and 1 to 1.6 cm thick. The fruits and seeds are consumed by many animals,
highlighting the keystone function of Almendro (Mills et al., 1993; Ruiz et al., 2005).
Bonaccorso et al.(1980) recorded sixteen species of mammals and Flores (1992) observed
around 100 species of birds feeding on its fruits and seeds. The critically endangered great
green macaw (Ara ambiguus), of which less than thirty breeding pairs remain in Costa Rica
(Chassot et al., 2009), is among the associated fauna that depends on Almendro not only as
a food source, but moreover as nesting site (Monge-Arias et al., 2003; Madriz-Vargas, 2004;
Ruiz et al., 2005; Hanson et al., 2006). Boddiger (2003) summarized the conflicts and ongoing
great green macaw conservation efforts in Costa Rica.
Almendro is not only famous for its high ecological value, but mostly because of its economic
value. The very durable and medium-textured wood rates high in mechanical resistance and
has a brown-yellow sapwood and yellow-red heartwood. With wood densities between 0.83
and 1.09 g/cm3 (Vozzo, 2002; Carpio Malavassi, 2003) this species is considered extremely
15
LITERATURE REVIEW
heavy and valuable, reaching the highest wood prices on local markets (Rodriguez and
Chaves, 2008). The wood is difficult to saw due to its weight, density and crystalline deposit
content, hence commercial exploitation of Almendro could not start before the 1980s when
improved saws and milling technology had been introduced (Flores, 1992; Butterfield, 1995).
It is used for floorings, bridges, railroad ties, boats, marine construction, handicrafts,
veneers, industrial machinery, sport implements, springboards and agricultural tool handles
(Jiménez et al., 2002; Carpio Malavassi, 2003). Finally, Almendro is appreciated for its
excellent wood, but as one of the prettiest trees in the forest, Almendro with its purple
flowers has also great potential for use as an ornamental tree. Moreover, indigenous people
benefit from the medical use of parts of the tree, and its nutritious seeds are supposed to
taste delicious when roasted (Standley, 1937)
Almendro was once a widespread species, but suffered severely from habitat destruction
and timber extraction. In Costa Rica and Nicaragua this species is listed as an Appendix III
species by CITES, the Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES, 2008). Furthermore, the Costa Rican ministry of environment and
energy (MINAE, Ministerio de Ambiente y Energia) completely banned the exploitation and
extraction of Almendro from natural forests in September 2008 (Ávalos, 2008). Since that
time, the Costa Rican wood industry mainly processes Almendro from Nicaraguan sources.
2.2 Almendro in timber plantations
Research on native tree species for timber plantations in Costa Rica and Panama is relatively
young. Some 24 years ago, in 1985 the first experimental plots using Almendro were
established by the “Organization for Tropical Studies” (OTS) in La Selva, Sarapiqui, Costa
Rica. In the 1990´s more research projects followed, such as the “Cooperación en los
Sectores Forestales y Maderero” (COSEFORMA) project in the northern zone of Costa Rica,
and in 1991 the EARTH University in Guácimo also included Almendro in their research.
Shortly later the “Comision de Enlace para el Estudio de Especies Forestales Nativas de la
Zona Norte y Atlantica” was founded in 1992 to coordinate and support the research of
16
LITERATURE REVIEW
native species in Costa Rica
(Müller, 1993). Mora-Chacón (2002) has documented a
complete history of native species research in Costa Rica.
Only native species with the highest priorities for commercial plantations have been selected
for investigations and Almendro was included for its resistant and durable wood. In contrast
to other timber species, which only have national markets, Almendro was also selected
because of its potential as timber export (Müller, 1993).
Native species research in Panama was for the most part carried out by the Smithsonian
Institute and first research outcomes for Almendro on plantations were published by Condit
in 1993. Since 2001, the joint “Native Species Reforestation Project” (PRORENA) between
the Smithsonian Tropical Research Institute and the Yale School of Forestry is coordinating
ongoing research on trees native to Panama. Like in Costa Rica, Almendro was included in
native species research projects in Panama, because of its high commercial value (Ugalde
Arias and Gómez Flores, 2006).
Before the early 90´s, native species were not been recommended for commercial
reforestation programs as up to date information did not exist, but since this time many of
the identified research gaps have been filled. Information about seed sources, species site
requirements and silvicultural management are available for numerous native species.
Despite the great potential of Almendro determined long ago, the situation is completely
different. Neither silvicultural management schemes nor general growth models or site
classifications exist for Almendro.
Information for the first stages of plantation establishment such as the treatment of seeds
(González, 1999) or nursery seedling growth exist (Russo and Sandí, 1995). Also, studies
about the initial growth behavior were published for Costa Rica (Butterfield, 1995) and
Panama (Wishnie et al., 2007).
17
LITERATURE REVIEW
A few growth reports for older Almendro plantations were published, such as the growth in
mixed and pure plantations in humid tropical Costa Rica (Petit and Montagnini, 2006); the
growth characteristics on farms in humid lowlands of Costa Rica (Piotto et al., 2003) and in
silvopastoral systems (Montagnini et al., 2003); performance, growth equations and rotation
ages in mixed and pure plantations in the humid neotropics (Petit and Montagnini, 2004);
the effects of thinning for pure- and mixed plantations with Almendro (Piotto et al., 2003);
the response to reforestation strategies on abandoned farmland in Panama (Hooper et al.,
2002); and the performance of native species and preference of farmers in Costa Rica and
Nicaragua (Piotto et al., 2003).
A comprehensive study about the growth behavior of Almendro took place on the
COSEFORMA plots in the Northern Zone of Costa Rica. These findings were published by
Delgado et al. (2003). Growth results after 11 years for three different sites (humid Ultisol,
very humid Ultisol and very humid Inceptisol) were presented along with a growth model to
predict diameter and height-growth based on the Schumacher model. His results indicated
that after 11-years Almendro performed the best on sites with an Ultisol soil profile.
However, the rotation time of D. panamensis is assumed to be 25 to 35 years according to
Petit and Montagnini (2004), while Montagnini et al. (2003) estimate a rotation period of 22
to 32 years. Through third-degree polynomial regression analysis growth equations for a
number of native tree species in the Atlantic lowlands of Costa Rica were developed (Petit
and Montagnini, 2004), but the growth of Almendro was to premature for extrapolative
modeling, hence only interpolative equations in the form of second-degree polynomials
were assigned to this species. Finally, model projections of Almendro are limited to 11-years
Delgado et al. (2003) and 12-years Petit and Montagnini (2004), thus covering only half of
the predicted rotation time and both models are not suitable for extrapolations.
Several publications, which are focusing more on the general effects of timber plantations
than on silviculture, mention Almendro as well. Many authors (Fisher, 1995; Parrotta et al.,
1997; Carnevale and Montagnini, 2002; Butler et al., 2008) emphasize that timber
plantations of indigenous tree species can support secondary forest succession by improving
18
LITERATURE REVIEW
soil conditions, attracting seed-dispersal agents, and providing shade necessary for
understory growth.
Also leaf litter decomposition and mulch performance of Almendro have been described
(Byard et al., 1996) as well as the direct effect of Almendro on soils (Montagnini and Sancho,
1994; Montagnini, 2000). Almendro is a leguminous tree, although Montagnini (200) could
not find any N-benefits, which can perhaps be ascribed to missing Nodulates on the roots.
However, higher levels of K were found under plantations of Almendro in a trial at La Selva,
Sarapiqui in the Atlantic lowlands of Costa Rica (Montagnini, 2000), underlining the direct
effect that timber plantations can have on soils.
2.3 Agroforestry and carbon forestry using Almendro
Various authors highlight the potential of Almendro for agroforestry systems and carbon
forestry projects.
It has been established that Almendro is a useful tree for agroforestry systems, (Haggar et
al., 1998; Haggar et al., 2003), referring to crop-tree combination with Pineapple (Ananas
spp.). Montagnini et al. (2003) described growth characteristics of Almendro in silvopastoral
systems, an agroforestry system where the production of livestock and trees takes place on
the same land-unit (Klopfenstein et al., 1997). Because of its open crown architecture,
Almendro builds a relatively translucent canopy that produces only moderate shade, thus
allowing the simultaneous growth of crops like pineapple, cacao and other cash or forage
crops. With its good timber quality and high economic value, Almendro can generate extra
income for local farmers and may therefore be a good choice for many kinds of agroforestry
systems.
Besides the production of timber, or timber in combination with crops and cattle in
agroforestry systems, timber plantations provide additional environmental services, such as
carbon sequestration (Montagnini and Porras, 1998; Shepherd and Montagnini, 2001;
Montagnini and Nair, 2004). Therefore, timber plantations in tropical countries, like Costa
19
LITERATURE REVIEW
Rica or Panama, have been proposed as one feasible option to offset emissions to mitigate
climate change. Through photosynthesis carbon dioxide (CO2) is fixed in the biomass of the
tree and sequestered in the key components of forest ecosystems, both as aboveground
biomass and belowground biomass (Montagnini and Porras, 1998).
Almendro has been identified as the best option and most promising species for long term
carbon sink reforestation projects in Costa Rica (Redondo-Brenes and Montagnini, 2006;
Redondo-Brenes, 2007). The study results indicate that fast-growing species accumulate
more carbon in the short-term (less than 10 years), but in the long-term slower growing
species such as Almendro accumulate more carbon due to different growth-patterns and
their high specific wood gravity.
20
METHODOLOGY
3. METHODOLOGY
3.1 Study area
Investigations covered timber plantations in the two Central American countries Costa Rica
and Panama. The majority of sample plots (68%) were located in Costa Rica, in particular in
the Atlantic lowlands of Costa Rica.
Panama with 77.382 km² has a greater land surface than Costa Rica (51.100 km²), but the
climatic conditions in Costa Rica and Panama are broadly similar. These countries belong to
the Neotropics and their climate is mostly tropical and in few parts subtropical. Due to
considerable relief within these two rather small countries, significant climate diversity over
relatively short distances can be discovered. Both countries have a central mountain range
and border two oceans. The Caribbean side is usually more humid than the Pacific side and
temperatures are lower at higher elevations. The numerous vegetative regimes contribute to
the country’s biodiversity and are often a direct result of elevation differences and
associated temperature and precipitation patterns. Still, two seasons can be distinguished,
the dry season from early December through late April and the wet season from late April
until the end of November.
Both countries are, as part of the isthmus between North- and South America, geologically
young, diverse and important in the context of geological history (Webb, 1991). Soils are
frequently derived from volcanic rocks (Palka, 2005). In Costa Rica 43 soil types are found
and in Panama 38 soil types, Inceptisols and Ultisols among the most common ones (FaoUnesco, 1990; Mata-Chinchilla, 1991).
Kapp (1999) provides a comprehensive summary of the climatic, geographic and edaphic
conditions of both countries and described their forestry sectors. The forestry sector is
generally more developed in Costa Rica, even if the total plantation area is bigger in Panama.
21
METHODOLOGY
3.2 Description of the sample plots
A total number of 131 sample plots, covering different physiographic, edaphic and climatic
conditions in both Costa Rica and Panama, were included in this study. Most of them were
permanent sample plots (PSPs), but 9 temporary sample plots (TSPs) were established on
plantations without any sample plots or on plantations where the original PSPs could not be
located anymore. 19 PSPs were abandoned and were re-measured for this study after
identifying the original tree numeration. Depending on the actual stocking, these sample
plots had been variable in size, mostly of rectangular shape and few circular ones. The
sample plots contained generally 25 trees or more. The northernmost sample plot was on
the plantation “Santa Cecilla” (11°11’N, 85°43’W) at the border of Costa Rica and Nicaragua
and the southernmost, “Soberania”, in the Panama Canal Region.
Figure 1: Map of the study area. Black dots indicate Almendro plantations included in this study.
Sample plots were distributed from 45 m.a.s.l up to 950 m.a.s.l and covered a precipitation
gradient from 1110 mm to 4500 mm.
Past land-use on plantations had been largely pasture and dominant soil types where either
Ultisols or Inceptisols. In both Costa Rica and Panama, the seed planting material originated
from identified Almendro seed trees in natural forests. Almendro plantations in Costa Rica
22
METHODOLOGY
were by and large established with seeds from identified seed trees in the Sarapiqui and
Guácimo region in the Atlantic lowlands and in Panama from seed trees in the Panama
Channel region (Butterfield, 1995; Russo and Sandí, 1995; Wishnie et al., 2007).
Plantations were typically established in 3 x 3 m spacing, few in 2 x 2 m spacing and some
individual ones 4 x 4 m, 5 x 5 m up to 6 x 6 m. The mixed Almendro plantations were
frequently spaced asymmetrical, such as 3 x 5 m or 3 x 4 m.
Plantation establishment normally included manual weeding and cleaning in the first years,
however sometimes also Glyphosphat was used to remove competing vegetation.
Management was concentrated primarily on the establishment, but silvicultural intervention
like thinning and pruning did not take place in most of the plantations.
3.3 Data collection
Growth data from 36 timber plantations, scattered in Costa Rica (26) and Panama (10), was
collected from March 2009 until the end of May 2009. Overall, this study covers a total of
131 sample plots as mentioned before.
Wherever necessary and possible, stands had been re-measured either on existing PSPs or
on newly established TSPs. All plots were mapped using a GPS handheld (Garmin - GPSmap
60Scx) and altitude was measured with the device´s barometric altimeter. Recordings were
taken of diameter at breast height (DBH) and the total tree height (h). The diameter was
measured with diameter tape, but on a few plantations (<20%) a caliper was used. Tree
heights were measured using a clinometer (SILVIA - Clino Master). For 8 plantations, only a
representative amount of tree heights (+/- 25) could be collected due to time constraints.
For these plantations, missing tree heights have been generated using the Michailofffunction, see chapter 3.6.
For the creation of growth series, scientists and plantation owners provided their growth
records as Excel files, for years prior to 2009. These Excel files were then processed with the
23
METHODOLOGY
software MIRASILV 3.2 (Sistema de manejo de información sobre recursos arbóreos en el
componente de silvicultura) to clean and organize the data for analysis (including more than
22000 measurement records). MIRASILV was developed at CATIE under the supervision of
Ugalde (2003). MIRASILV was used for a plausibility check of all records, and accordingly
negative growth records and outliers were excluded before starting the data analysis. A list
with detailed description of all plantations can be found in Annex 1.
Table 1: List of own measurements and data sources for growth data prior 2009
Country Institution
Data source
# of plantations
CR
OTS – La Selva
Own measurements + external 3
CR
ITCR / COSEFORMA
Own measurements + external 7
CR
RTT
External data
3
CR
CATIE
External data
5
CR
EARTH
Own measurements + external 4
CR
PRECIOUS WOODS
External data
1
CR
LOS TUCANES
External data
1
PA
FOREST FINANCE
Own measurements + external 6
PA
PRORENA
External data
6
3.4 Data analysis
The methodology had to be adapted to account for the fact that the data sets provided
originated from heterogenic plantations in terms of site, age, initial spacing and silvicultural
management. Various forest mensuration methods were used on all plantations and the
provided data set were not always consistent.
All plantations were clustered into 9 site groups (SIGR) and 3 age classes (AGCL), based on
their location and age. The SIGRs were then numbered from north to south and east to west.
24
METHODOLOGY
Table 2: List of age classes, their ranges and frequencies
Age class
Range
# of Plantations
in CR
in PA
1
<8 years
17
12
5
2
8-16 years
13
8
5
3
>16 years
6
6
-
The classification of SIGR in Costa Rica incorporated biotic units, soil types, geology, life
zones and relief (Ortiz and Cordero, 2008), whereas in Panama the grouping was based on
Isohyets, Isotherms and elevation (Hydromet, 2009) due to different data availability.
Table 3: List of site groups and their attributes.
STGR
Annual precipitation
# of dry
Elevation
Dominant soil
# of
Nr.
(mm)
months*
(m)
type**
plantations
COSTA RICA
1
2000 - 2500
3-4
<400
Ultisol
3
2
2500 - 3000
1-2
<200
Inceptisol
2
3
3000-4000
1
<200
Ultisol
6
4
4000-5500
0
<200
Inceptisol
8
5
3000-3500
0-1
300 - 400
Inceptisol
3
6
2500-3000
0
600 - 1000
Ultisol
4
PANAMA
7
3000-3500
2-4
<200
Ultisol
7
8
<2000
4-6
<300
Alfisol
2
9
2000 – 3000
2
<200
Ultisol
1
* Months with less than 100mm rainfall
** Detailed information about soil types in Panama could not been obtained, as a country
wide soil type mapping never took place. The used information for Panama originate from the
Harmonized World Soil Database (Fischer, 2008). Soil data from the Digital Atlas de Costa Rica
was used for all sites in Costa Rica (Ortiz and Cordero, 2008)
Data analysis was then conducted using MIRASILV v.3.2., the Statistical Package for Social
Science (SPSS, Version 16) and Microsoft Excel 2007 (Harris, 1998).
25
METHODOLOGY
Stand parameters for each plot and plantation were calculated, such as mean diameter (dg),
mean height (hg), top diameter (d50), top height (h50), basal area (G) and Volume (V). For
plantations with more than one sample plot, average values from all sample plots were
calculated. All stand parameter where finally extrapolated to hectare values. To illustrate the
availability of trees with diameters suitable for commercial use, diagrams of the stand
diameter distribution were drawn using a 2 cm scale. These diagrams are also supposed to
illustrate the great variety of Almendro stand scenarios.
The methodology aimed to harmonize all measurement records and to present stand
parameters, which allow a comparison between sites and management schemes. This would
have not been possible when using mean values, which are in general strongly influenced by
stand management schemes. Therefore, primarily top height and top diameter are
presented in the results chapter instead of mean height and mean diameter. With these top
values, the potential of Almendro plantation can be expressed independently from
insufficient management interventions.
To save time and money, several plantation owners measured representative tree heights
and generated tree heights for the rest of the stand using stand height curves (SHC). This
approach had to be adopted also for the calculation of the top height, the average total
height of a specified number of the thickest trees in a stand.
Top height (h50) and top diameter (d50) were calculated for the 50 strongest trees, as it was
assumed that at the end of the rotation age no more than 200 Almendro trees per hectare
remain on a plantation. Teak (Tectona grandis) plantations in Costa Rica normally yield 120
to 185 final crop trees according to Bermejo et al. (2004). In this case, 100 trees would
represent more than half of all trees, thus not representing the strongest ones.
As mentioned before, stand-height curves were used to calculate the top height (h50). For
that reason, the quadratic-mean diameter of the largest 50 trees, the top diameter (d50), was
entered into the Michailoff-function (see Chapter 3.6.) to estimate the corresponding top
26
METHODOLOGY
height. Similar approaches are adopted in New Zealand and the UK to avoid subjective
selection of the tallest trees (Brack, 2000). Dominant height (hdom) could not be taken into
account, hence not all tree heights were measured on all plantations, but in very young
plantations where no diameter values were available, the dominant height had to be used
instead of the top height, thus representing the mean height of the 50 tallest trees per
hectare.
For tree volume (V) and basal area (G) calculation the following formulas were used:
Equation 1: Volume calculation
Where: V = tree volume, d = DBH, h = measured tree height and f = form factor*
*As no species specific form factor is available for Almendro, a form factor of 0.45 was assumed.
Equation 2: Basal area calculation
Where: G = tree basal area and d = DBH
The respective hectare values were then calculated as the sum of all single tree values.
After the calculation of all stand characteristics, the following steps were taken:
-
Development of stand height curves, using the Michailoff-function, see chapter 3.6.
-
Creation of site index curves based on the top height/plantation age ratio using the
Chapman - Richards function (chapter 3.7)
-
Projection of top-height growth for one rotation period of 25 years, using the
Chapman - Richards function (chapter 3.5)
27
METHODOLOGY
3.5 Growth modeling
Reliable estimates of wood production are fundamental for sustainable forest management
on any forest level. These forecasts of growth and yield depend on silvicultural practices,
estimates on site productivity and the models used.
The evolution of growth modeling started with “static” growth models at the beginning of
the 18th century. They had the form of basic yield tables and were rather simple growth
predictions, only valid for pure-, even-aged stands, on particular sites under standardized
silvicultural treatments (Alder, 1980; Tesch, 1981).
A substantial change in growth and yield determination began around 1935 when statistical
techniques where applied on growth data and growth formulas evolved that were able to
project growth for many situations (Tesch, 1981).
Nowadays, some forest growth models are more “dynamic” and not only able to predict
future yield, in addition they even allow forest managers to explore several silvicultural
options, like forest simulators in Germany, such as SILVA (Pretzsch et al., 2002) or BWinPro
(Nagel et al., 2002). Growth models form a continuum from yield tables to single tree models
(Leary, 1991) and their development over the last 200 years had been profoundly described
by Tesch (1981) and Skovsgaard and Vanclay (2008).
Nevertheless, the situation in tropical countries is exceptional as advanced growth modeling
is relatively rare. Only a few provisional yield tables and some growth models exist, and
generally only for widely used commercial species like Teak (Tectona grandis), Eucalyptus
spp. or Pinus spp.. In Costa Rica and Panama, growth models are available for exotic species
such as Teak (Bermejo et al., 2004; Perez and Kanninen, 2005) and for few native species
(Somarriba et al., 2001; Cordero et al., 2003), but as mentioned in chapter 2.2, no reliable
growth models that are applicable on various sites exist for Almendro.
28
METHODOLOGY
Numerous growth functions, able to describe plant growth processes, are available
(Bredenkamp and Gregoire, 1988; Garcia, 1988; Zeide, 1993). The Chapman-Richards
function (Richards, 1959) embodies commonly used growth functions such as
monomolecular, Gompertz, and logistic equations and has been widely applied in forestry
due to its flexibility, accuracy, and meaningful analytical properties (Pienaar and Turnbull,
1973; Shifley and Brand, 1984; Yuancai et al., 1997; Zhao-gang and Feng-ri, 2003).
The Richards function has been used as well in this study to develop growth curves of topheight growth.
Equation 3: Chapman - Richards function
Where: H = height, a = upper asymptote, t = time, and b, c, d = parameters
Further aspects of growth modeling have been described by many authors (Vanclay, 1992;
Vanclay, 1995; Vanclay, 1997; Vanclay and Skovsgaard, 1997).
3.6 Stand height curves
Stand height curves represent the correlation between tree height and DBH in a forest or
timber plantation. In a scatter diagram with the measured DBH on the X-axis and the
measured height on the Y-axis the correlation between the two variables (DBH and height) is
visualized in a point cloud, which can be fitted to a stand height curve either graphically or
mathematically. The mathematical methods follow the “least squares method” and a variety
of equations have been proposed to fit height curves (Schmidt, 1967), each suited to
different forest types, stand ages and structures.
29
METHODOLOGY
The shape of the curve changes with the development and growth stage of the stand,
indicating the following (Brack, 2000; Kramer and Akça, 2002):
-
Steep sloped curves indicate a young stand, which is still sorting out dominance.
-
Shallow or flat slope may indicate a mature to over-mature stand, or a stand
modified by thinnings.
-
A right-hand-side of the curve that is relatively high indicates a good site.
As the nature of the curve changes with age, no single method is likely to be satisfactory for
all situations.
For this study the Michailoff and Petterson equations (Michailoff, 1943; Kramer and Akça,
2002) were used to fit the observed values to a curve. Especially the Petterson function is
suitable for all-aged stands with wide diameter class dispersion, like the unthinned
Almendro plantations in Costa Rica and Panama.
Equation 4: Petterson - height curve function
Where: h = (predicted) tree height, ao, a1 = regression coefficients, d = diameter at breast height
However, the Michailoff-function showed better fit for most of the Almendro stands and
was therefore used in this study.
Equation 5: Michailoff - height curve function
Where: h = (predicted) tree height, ao, a1 = regression coefficients, d = diameter at breast height
Measuring the height of all trees in a stand is time consuming and therefore stand height
curves were used to predict the height of trees where only the height of a representative
30
METHODOLOGY
limited number of trees was measured. This was the case for the 2009 measurements on
seven plantations from the COSEFORMA project (“Los Almendros”, “Buenos Aires”, “Cope
San Juan”, “Montealegra”, “E. Romero”, “O. González”, “O. Rodriquez”) and the plantation
“Santa Cecilla”. The determination of tree heights through this method is facilitated by the
relative strong stochastic relationship between the DBH and tree height for each tree species
in a stand.
Besides, the Michailoff height curve function was used to determine the top height for the
50 strongest trees in all stands, as described in chapter 3.4.
3.7 Site classification
Forest yield determination and site classification were ever closely linked, as on some sites,
forests grew better than on others. Differences of soil conditions (e.g. fertility, drainage),
climate (rainfall and temperature patterns) and topography (e.g. altitude, slope) are
reflected in tree performance, requiring an evaluation of these site varieties to be able to
give reliable forecasts of growth and yield (Vanclay, 1992). Various sites classifications exists,
such as site index, site quality, and site class or site productivity. An uncomplicated method
for site classification is a visual assessment of the site quality into relative classes (i.e. good,
poor). Site class is a more objective classification into a number of classes and site
productivity is a general term for the potential of a certain tree species to produce timber.
The most common way to assess the site quality is the site index, but as for site quality and
site class it is an approximate measure of the true site productivity (Vanclay, 1992). For a
review of the history and basic principles of site classification see Skovsgaard and Vanclay
(2008).
The productive capacity of the site affects both the volume of timber production per hectare
and the age of maximum mean annual increment (MAI) culmination. Good sites take a
shorter time to reach MAI culmination age and produce more timber as compared to poor
sites (Pandey, 1987). Besides the influence on growth factors, site selection also affects
31
METHODOLOGY
susceptibility to forest pest. Planting trees on unsuitable sites favors a high probability of
pest outbreaks (Speight and Wylie, 2001).
In the tropics, direct methods to determine the productive potential, such as quantifying
climate, soil or indicator plants, are rather uncommon; instead site indices (SI) are used to
determine site classification. The site index (SI), is represents the stand top height at a
specific age, and is often estimated using a top height-age curve. Although true site
productivity may not be fully represented by SI, SI is the most widely accepted and probably
the most simple method for estimating site productivity (Sharma et al., 2002).
The top-height is widely accepted as site productivity indicator for even-aged forests as it is
little influenced by silvicultural interventions, given that thinnings are not from above (Brack,
2000; Evans and Turnbull, 2004). Trees used in the estimation of site index should rank
among the upper social classes and top heights represent those leading trees, thus being a
very stable height-based indicator of site productivity (Skovsgaard and Vanclay, 2008;
Kramer and Akça, 2002; Sharma et al., 2002; Vanclay, 1992).
Growth models allow foresters to locate the equivalent top height-age curve to classify and
project the growth of their stands, based on measured top height and known age of a stand
(Avery, 1994). Because of its flexibility, the Chapman-Richards equation is often used to
model this top-height growth pattern. This study makes use of this equation for similar
reasons, see Chapter 3.6.
Site indices exist for few species in Costa Rica and Panama, such as Tectona grandis (Bermejo
et al., 2004; Perez and Kanninen, 2005), Cordia alliodora (Somarriba et al., 2001),
Bombacopsis quinata (Cordero et al., 2003) or Terminalia amazonia (De los Santos-Posadas
et al., 2006).
32
RESULTS
4. RESULTS
In this chapter, growth records from all plantations in each site group are presented and
stand characteristics for selected plantations are described. Subsequently the top-height
growth dynamics of Almendro are illustrated for all development phases (young-, medium
and older plantations). Site indices are developed on the basis of the top height growth,
together with growth projections of top height for one rotation period.
4.1 Growth of Almendro in Costa Rica and Panama
4.1.1 Site group 1, CR
In the north-easternmost region of this study, bordering Nicaragua, three commercial
Almendro plantations (all AGCL 1) were visited. The plantations are located in the climatic
transition zone between the dry climate of the Pacific lowlands and the wet Atlantic
lowlands climate. With annual rainfall ranging from 2000 - 2500 mm and 3 - 4 dry months,
the climate is the driest in comparison to all other site groups in Costa Rica.
“Santa Cecilla” is managed by the Swiss based tropical forests management company
Precious Woods (http://www.preciouswoods.com). The plantation is mainly stocked with
Teak (Tectona grandis) and native species have been typically planted on a trial basis, except
for Pochote (Bombacopsis quinata), the most frequently used native species for commercial
purposes on their plantations.
A small patch of 2 ha, 110 m.a.s.l, was reforested with Almendro in 2001 on flat terrain. The
spacing was 3 x 3 m and two thinnings have been conducted so far. 120 trees per hectare
were removed in 2006 and another 200 trees per hectare in 2008. The thinnings have not
been from below as one could expect for this stage of plantation development. During both
thinnings, trees of the upper classes were removed, as well as trees on the sample plot,
which were used for exemplary height measurements (chapter 3.6).
33
RESULTS
Two more plantations were situated in this site group, but on higher elevations between
300 to 400 m.a.s.l. These educational plantations are owned by a scientist working at CATIE,
who is demonstrating multiple use forestry, primarily with native species. Overall, more than
50 different native species are planted on these plantations and some of them in
agroforestry systems, along with Cacao (Theobroma cacao) and Vanilla (Vanilla planifolia).
On the plantations “Orosi” and “Cacao”, Almendro was planted basically in line plantings inbetween a great number of various native species.
Growth data was provided and subsequently analyzed. Table 4 shows the growth of
Almendro in this site group.
Table 4: Growth of Almendro in SIGR 1
Plantation
Santa Cecilla
Orosi
Cacao
Years Months
d50
h50
G
V
-1
3
Stocking
-1
(cm)
(m)
(m² ha )
(m ha )
trees ha-1
1.6
19
4.3
3.5
0.7
1.0
920
2.6
31
7.1
6.7
1.7
4.4
900
3.6
43
10.2
9.0
3.6
13.0
900
4.7
56
13.3 11.5
6.3
29.6
900
5.6
67
15.5 11.7
8.0
40.0
780
6.8
81
16.1 15.6
9.3
61.4
780
7.8
93
18.2 16.0
9.8
66.8
580
3.0
36
5.3
5.6
0.5
0.9
542
4.0
48
8.0
7.1
0.9
2.4
542
4.0
48
6.0
5.8
0.4
0.8
667
5.0
60
8.8
7.1
0.7
2.2
333
4.1.2 Site group 2, CR
A short dry period of 1 - 2 month, annual rainfalls of approximately 3000 mm and Inceptisols
as dominant soil type are characteristic for this site group. In a 4-year old agroforestry
system (“Tamara AFS”), where Almendro was planted together with Cacao (Theobroma
34
RESULTS
cacao) and Banana (Musa spp.) in a 12 x 12 m spacing, high initial growth rates were
observed of 1.9 m per year in top height and 2 cm in mean DBH (2.3 cm per annum for d50).
Compared to the other Almendro plantation in the same site group (“Montealegra”: 18
years old, 3 x 3 m spacing), the agroforestry system showed faster initial diameter growth,
but slower height growth. The plantation in “Montealegra” was managed as silvopastoral
system and reached equal values around two years later.
Table 5: Growth of Almendro in SIGR 2
Plantation
Tamara AFS
Montealegra
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
3.8
46
8.6
7.1
0.3
0.9
69
2.1
25
4.2
4.0
0.6
0.8
1111
3.1
37
7.3
5.8
1.6
3.3
1100
4.1
49
9.4
8.6
3.0
9.3
1100
5.1
61
10.2 10.3
3.8
14.5
1089
6.1
73
11.8 11.1
5.0
20.8
1033
7.1
85
13.6 12.7
5.8
27.4
967
8.1
97
13.9 13.1
6.2
30.6
956
11.1
133
16.9 16.8
9.5
61.0
867
18.4
221
22.0 18.2
11.7
76.3
700
4.1.3 Site group 3, CR
Site group 3 contains the greater part of the Almendro reforestations that had been
established during the COSEFORMA project. The COSEFORMA project was a German – Costa
Rican development project between the German Technical Cooperation and local forest
authorities, promoting sustained and efficient use of forest resources.
35
RESULTS
Table 6: Growth of Almendro in SIGR 3, AGCL 3
Plantation
Oscar Rodriquez
Los Almendros
Cope San Juan
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
2.0
24
3.8
3.7
0.7
1.0
1100
3.0
36
5.4
5.0
1.6
3.1
1100
4.0
48
7.1
6.3
2.7
6.9
1100
5.0
60
9.6
9.1
5.2
19.5
1100
6.0
72
11.0 10.9
6.5
29.9
1089
7.0
84
12.8 12.5
7.1
37.1
956
8.0
96
13.7 13.3
8.1
45.4
956
11.0
132
16.8 14.5
11.0
65.4
956
18.4
221
22.7 19.7
12.0
94.1
667
2.8
34
3.5
3.5
0.1
0.1
1067
3.8
46
5.4
5.3
0.3
0.4
1044
4.8
58
8.7
7.3
1.4
3.2
1022
5.8
70
10.6
8.8
2.3
7.0
1000
6.8
82
12.8
9.7
3.8
13.6
944
7.8
94
13.9 10.8
4.8
20.0
944
10.8
130
19.9 13.4
8.8
45.3
919
18.4
221
28.7 20.7
15.1
117.1
889
1.8
22
3.9
4.3
0.4
0.6
1111
2.8
34
6.6
6.8
1.5
3.6
1100
3.8
46
8.4
9.0
2.7
8.9
1100
4.8
58
11.0 11.7
4.5
19.3
1089
5.8
70
12.1 13.9
5.2
26.4
1078
6.8
82
13.6 15.2
6.4
35.8
1044
7.8
94
14.4 15.3
7.1
41.2
1044
10.8
130
18.0 18.7
10.0
71.4
989
18.4
221
23.4 22.3
14.4
126.3
956
36
RESULTS
In early 1990, reforestations with native species were initiated on private farmland in the
northern zone of Costa Rica, with funds from the COSEFROMA project. Soils in this site group
belong to the Ultisol order and annual rainfall fluctuates around 3000 mm.
All experimental plantations were planted in 3 x 3 m spacing on former pasture land and
have similar management histories (cleaning and weeding in the first years, no thinning). The
three plantations “Edwin Romero”, “Olman González” and the plantation “Buenos Aires”
were established in 1994, thus belong to AGCL 2. The others were planted in 1990 (“Cope
San Juan”, “Los Almendros” and “Oscar Rodríquez”) and respectively belong to AGCL 3. More
detailed descriptions of all plantations can be found in Delgado et al. (2002).
All plantations were established on private farmland in cooperation with local farmers. Some
of them used the reforested area for cattle crazing, so that three plantations (“Los
Almendros”, “Edwin Romero” and “Olman González”) can be considered as a silvopastoral
systems. For a general description of silvopastoral systems see Klopfenstein (1997). “Cope
San Juan” supported the highest total stand volume, as 965 trees remained on the
plantation after 18 years. Mean diameter (dg) was respectively the lowest, but trees the
highest (h50), when compared to the other plantations of the same site group.
The highest top diameter (d50) of 28.7 cm was observed in “Los Almendros“. Considering h50,
“Cope San Juan” ranked first, “Los Almendros” second and “Oscar Rodriquez” third.
From the three younger plantations, Buenos Aires had the largest diameter and biggest
height values. Mean diameter (dg) in Buenos Aires was the largest in this site group and
exceeded the values of the older plantations. Plantation “Edwin Romero” performed better
than “Olman González”. For the whole site group basal area (G) was the highest on the
plantation “Edwin Romero”. With 850 trees per ha and a total standing volume (V) of 121.7
m³/ha, V in “Edwin Romero” was only 4.6 m³/ha lower compared to the plantation “Cope
San Juan”, which was three years older and had the highest standing volume of the site
37
RESULTS
group. The lowest current stocking of 590 trees/ha was observed on plantation “Olman
González”.
Table 7: Growth of Almendro in SIGR 3, AGCL 3
Plantation
Buenos Aires
Edwin Romero
Olman González
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
1.3
16
2.8
2.8
0.2
0.2
1111
2.3
28
6.4
6.0
1.4
3.0
1070
3.3
40
8.1
7.6
2.4
6.8
1056
4.3
52
10.4
9.5
4.2
15.4
1056
7.3
88
16.1 12.5
9.0
45.5
1043
14.8
178
24.2 20.9
13.8
115.4
617
1.3
16
4.3
4.3
0.7
1.2
1029
2.3
28
6.4
6.3
1.7
4.1
1029
3.3
40
9.4
9.1
3.7
12.4
1015
4.3
52
10.2 10.0
4.5
16.9
1015
7.3
88
14.9 14.8
9.4
57.7
933
14.8
178
21.0 20.1
16.1
121.7
850
1.3
16
2.0
2.4
0.0
0.0
1084
2.3
28
4.4
4.8
0.5
0.8
837
3.3
40
6.9
6.8
1.2
3.0
741
4.3
52
8.2
7.7
1.7
5.1
700
7.3
88
14.2 11.5
5.0
22.3
700
14.8
178
19.5 16.5
7.5
48.1
590
4.1.4 Site group 4, CR
This site group covers the Atlantic lowlands of Costa Rica. The region is characterized by high
annual rainfalls of 4000 to 5500 mm and soils of better productivity, such as Eutropepts or
Dystropepts. Most soils under Almendro in this site group however, belong to the Ultisol
38
RESULTS
order. One commercial plantation (“Los Tucanes”) and seven scientific plantations are part
of SIGR 4.
Numerous publications are available for this climatic zone as the major part of research on
Almendro was conducted in this region, yet most of the scientific plantations did not receive
constant silvicultural management.
Still, groundbreaking information about the performance of Almendro in natural forests .
(Clark and Clark, 1987; Fichtler et al., 2003; O'Brien et al., 2008) and on timber plantations
(Montagnini and Sancho, 1994; Butterfield, 1995; Stanley and Montagnini, 1999; Carnevale
and Montagnini, 2002; Petit and Montagnini, 2004; Petit and Montagnini, 2006; RedondoBrenes and Montagnini, 2006) were gathered especially, on the sample plots in the research
station La Selva (10°26’N, 86°59’W), managed by the Organization for Tropical Studies (OTS).
The mean altitude of the mostly flat terrain is 50 m, mean annual temperature is 24 °C and
the mean annual rainfall amounts 4000 mm. The “Canadian Trial” and “Montagnini” plots
were established on deep, well-drained and stone free Fluventic Dystropepts derived from
volcanic alluvium with pH values below 5. Sample plot “J. Haggar” was established on
Ultisols. For a in depth description of the soils of the research station La Selva see Sancho
and Mata (1987).
The oldest reforestation in Las Selva using Almendro was established in 1985 as part of the
TRIALS project (Butterfield and Fisher, 1994). This plot (“Canadian Trial”) was planted with
49 Almendro trees in 2 x 2 m spacing and the plot descriptions and early growth results can
be found in Butterfield (1995). After 24 years, 14% of the originally planted Almendro trees
survived. Seven trees remained on the plot (sample plot size: 196 m²), thus representing 357
trees per hectare. The measured mean DBH (dg) was bigger 30 cm and the tree in the highest
diameter class (d50) measured 39.6 cm. Basal area (G) was 27.6 m²/ha and total stand
volume 410 m³/ha. All trees were straight and of good form. Measured heights until the first
branch, the commercial height, averaged 14.2 m.
39
RESULTS
Based on the observations from this plot, the rotation age for Almendro was assumed to be
25 years as this species can produce a target diameter of over 30 cm in this period. This
assumed rotation age resembles the assumptions from Petit and Montagnini (2004).
Table 8: Growth of Almendro at “La Selva”, SIGR 4, AGCL 3
Plantation
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
Canadian Trials
24.0
288
39.6 33.7
27.6
410.0
357
Jeremy Haggar
14.8
178
29.9 23.9
19.1
188.3
500
2.3
28
5.8
5.8
1.7
3.7
1860
3.3
40
9.1
9.1
5.0
17.4
1786
4.3
52
11.6 11.3
5.8
26.5
1131
6.8
82
16.1 16.5
7.3
46.0
833
7.9
95
17.5 18.4
10.4
72.0
833
9.9
119
18.7 19.0
11.3
84.4
670
17.6
211
25.1 29.3
18.2
196.6
1094*
2.3
28
6.1
6.5
2.0
4.5
2068
3.3
40
9.4
9.4
5.4
19.0
2024
4.3
52
12.1 12.4
8.1
38.3
2024
6.8
82
16.1 16.0
11.7
67.5
1994
7.9
95
18.7 17.2
14.0
85.0
1994
9.9
119
21.1 18.6
12.1
84.4
863
17.6
211
21.3 25.9
27.2
260.4
1875*
Montagnini
(Thinned)
Montagnini
(Unthinned)
*These values originate from TSPs and will be discussed in Chapter 5.1.
Growth on the “Montagnini” and “J. Haggar” plots was measured as well. For the
“Montagnini” plots older growth data was available for almost 10 years of one thinned and
one unthinned block.
Trees on the “J. Haggar” plot were planted in 4 x 4 m spacing and in 2 x 2 m on the
“Montagnini” plots. The original permanent sample plots could not be found anymore as the
40
RESULTS
tree numeration was not visible anymore. Therefore, temporary sample plots had to be
established, although their size and amount were limited due to time constraints and
difficult access.
Some 50 km away from La Selva, four Almendro plantations on the campus (10°12’N,
83°37’W) of the EARTH University (Esucela de agricultura de la region tropical humeda) were
measured on temporary sample plots as well. These plantations were established for
investigations, commercial timber production and carbon sequestration. Some of the
Almendro plantations help to offset green house gas emissions of the University´s vehicle
fleet and the city of Rotterdam, the Netherlands. Since 1991 more than 400 hectares have
been reforested with native species on the campus of the EARTH University (Russo, 2002).
The terrain on the EARTH campus is flat at a mean altitude of 90 m.a.s.l. Mean annual
temperature is 26 °C and annual precipitation fluctuates around 3400 mm. The mainly
alluvial soils were derived from sediments and volcanic rocks.
“La Bomba”, the oldest plantation planted 17 years ago, was established in 3 x 3 m spacing
and management was primarily focused on the early years after plantation establishment.
Weeding and tending in the first years was not followed by a regular thinning regime, typical
for all other Almendro plantations at the EARTH University. Stem numbers at “La Bomba”,
were almost the same as on the seven years younger, but thinned “Montagnini” plot in La
Selva at an age of ten years. Trees with DBH smaller 5 cm were found together with trees
greater 30 cm in DBH, indicating the large range of tree diameters. Early growth data for this
stand was published by Russo (2002). Growth data for all “EARTH” plantations is given in
table 9.
The mean DBH of the medium aged plantation “Y-Griega” (9.3 years, AGCL 2, initial spacing:
3.5 x 3.5 m) was with 17.5 cm, 0.5 cm smaller than on the eight years older plantation “La
Bomba”, which had a higher initial stocking density.
41
RESULTS
One temporary sample plot was established on the plantation “Puente Hamaca”, on flat
terrain in close proximity of a river. The measured spacing was 4 x 4 m and mean DBH was
bigger than on the slightly younger plantation “Tiro al blanco”, which was established with
an initial spacing of 3.5 x 3.5 m.
Table 9: Growth of Almendro for “EARTH” and “Los Tucanes”, SIGR 4, AGCL 2 and 3
Plantation
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
La Bomba
17.3
208
28.6 23.1
17.6
151.2
691
Y-Griega
9.3
112
21.4 16.3
13.1
86
544
Tiro al blanco
4.6
55
12.8 12.3
5.6
28.7
663
Puente Hamaca
4.8
58
16.9 14.4
3.1
19.6
180
Los Tucanes 1
4.8
58
14.3 12.5
5.9
28.3
556
Los Tucanes 2
4.1
49
13.3 12.4
3.8
18.0
556
Data was also provided for “Los Tucanes”, the easternmost Almendro plantation in Costa
Rica (09°98´ N, 83.17’ W). This commercial Almendro plantation was established in 2004 at
an altitude of 175 m.a.s.l., on land that was formerly used for a timber plantation. After the
harvest of Eucalyptus (Eucalyptus spec.) and Laurel (Cordia alliodora), the land was replanted
with Almendro in a 3 x 4 m spacing.
On both sample plots, few Laurel trees remained, which overtopped the newly planted
Almendro trees. Almendro plots were planted at two different times, thus they are
considered separately even if management and spacing are the same. In the 9 months older
plot “Los Tucanes 1”, the top diameter was 1 cm bigger than in the younger plot “Los
Tucanes 2”.
4.1.5 Site group 5, CR
Mixed species Almendro plantation for carbon sequestration and timber production have
been established by the applied research organization Reforest the Tropics (RTT) on the
northern foothills of the Turrialba Mountains.
42
RESULTS
In cooperation with local farmers, RTT is planting new tropical forest with donations from US
sponsors to offset US-generated carbon dioxide (CO2) emissions. At present RTT balances the
CO2 emissions of over 50 US sponsors on a total number of 9 farms in Costa Rica
(http://reforestthetropics.org).
Data from three sample plots was provided for their “Hacienda Las Delicias“ (10°12’ N,
83°37’ W), 5 km away from the EARTH University (SIGR 4). Mean annual rainfall of 3414mm
was similar, although elevation was higher (mean altitude 320 m.a.s.l.) and mean annual
temperatures lower (21°C).
Table 10: Description of the species mixtures on “Hacienda Las Delicias”, SIGR 4.
Mohegan
ConCol
Trees
Spacing
/ha*
(m)
D.panamensis
625
4x4
A. hunsteini
312
4x8
E. deglupta
78
8 x 16
S.macrophylla
78
8 x 16
Species
CMEEC
Trees
Spacing
/ha*
(m)
D.panamensis
339
4x6
A. hunsteini
749
4x8
Species
Trees
Spacing
/ha*
(m)
D.panamensis
354
4x4
A. hunsteini
578
4x4
Species
*Tree numbers per ha at last measurement in March 2009.
RTT is planting Almendro in pure plantations and mixtures with native species, such as
Mahogany (Swietenia macrophylla) and exotic species, such as Klinkii pine (Araucaria
hunsteini) and Eucalyptus (Eucalyptus deglupta). The mixtures are explained in table 10 and
respective growth data for the forests in which the Connecticut College (“ConCol”), the
Connecticut Municipal Electric Cooperative (“CMEEC”) and the Mohegan Tribe of Uncasville
Connecticut (“Mohegan”) balance their CO2 emissions are given in table 11.
43
RESULTS
Table 11: Growth of Almendro in SIGR 5, AGCL 2 and 3
Plantation
CONCOL-00
CMECC
MOHEGAN
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
7.3
88
20.1 14.2
4.7
27.7
339
8.1
97
21.6 17.6
5.7
40.1
339
2.3
28
-
4.4
-
-
380
3.3
40
7.2
6.6
0.7
1.7
367
4.3
52
10.4
8.0
1.4
4.5
362
5.2
62
13.3 10.0
2.5
10.4
354
6.3
76
15.8 12.2
3.8
19.4
357
7.3
88
17.9 14.1
4.8
28.5
354
8.3
100
18.7 15.9
5.2
34.3
354
0.8
10
-
1.1
-
-
563
1.8
22
4.4
4.9
0.4
0.7
617
2.8
34
7.0
6.7
1.1
2.9
605
3.7
44
9.3
8.9
2.1
7.4
602
4.7
56
11.7 11.0
3.3
14.4
602
5.8
70
13.9 13.1
4.6
24.3
594
6.8
82
16.0 15.9
5.5
34.9
582
4.1.6 Site group 6, CR
In the highlands of Costa Rica near the town of Turrialba (9°38’ N, 83°38’ W), Almendro
plantations were established by RTT and the Centro Agronómico Tropical de Investigación y
Enseñanza (CATIE).
Typical for this region are a distinct season with warmer temperatures from May to
November and a colder season from December to March. Mean annual temperatures are
22.5 °C and mean annual precipitation 2645 mm. The plantations “Mulas”, “CACTU” and “Las
Peñas” were situated on CATIE´s experimental Farm, 600 m.a.s.l. and one plantation (“San
Juan”) was established at 942 m.a.s.l., on hilly terrain that was formerly used as a dairy farm.
44
RESULTS
Soils in San Juan had good drainage and higher nutrient levels, while CATIE´s experimental
farm was formerly used for sugarcane production and soils were depleted, had poor
drainage and soils exhibit high water tables during the rainy season (Cuenca, 2009). Table 12
explains the species mixtures and in table 13 all growth records for this site group are listed.
Table 12: Description of the species mixtures in “Mulas” and “San Juan”, SIGR 6.
Mulas
Species
Trees
/ha*
San Juan
Spacing (m)
Species
Trees /ha* Spacing (m)
D.panamensis
360
5x5
D.panamensis
325
5x5
A. hunsteini
280
4x8
A. hunsteini
255
4x8
E. deglupta
40
10 x 20
E. deglupta
30
10 x 20
S.macrophylla
50
10 x 20
S.macrophylla
50
10 x 20
*Tree numbers per ha at last measurement in March 2009.
Performance of Almendro was better on the site in “San Juan” and very poor in “Mulas”. In
the mixed system in “Mulas”, Almendro grew inferior to all other species. Height growth in
“San Juan” differed and Almendro ranked second after E.deglupta.
Two more plantations of Almendro exist on CATIE´s experimental farm. They have never
been measured, as growth was lacking and the replanting with another tree species is
already planned. These plantations were visually assessed and average tree heights were
below 3 m.
Overall, the performance of Almendro in this site group was inferior, when compared with
all other site groups in Costa Rica.
45
RESULTS
Table 13: Growth of Almendro in SIGR 6, AGCL 2
Plantation Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
CACTU
7.6
91
8.9
5.8
1.1
2.4
486
Las Peñas
6.0
72
4.6
4.2
0.6
1.1
400
1.7
20
-
1.8
-
-
360
2.7
32
-
3.2
-
-
360
4.8
58
5.7
4.8
0.4
0.7
360
5.6
67
6.9
5.5
0.6
1.3
360
6.6
79
8.2
5.8
0.8
1.9
360
1.5
18
2.5
2.4
-
-
350
2.4
29
3.8
-
-
-
350
4.6
55
8.3
7.2
0.7
1.8
335
5.4
65
9.9
8.9
0.9
3.0
330
6.4
77
11.9 9.9
1.3
5.0
325
Mulas
San Juan
4.1.7 Site group 7, PA
The northernmost site group in Panama is classified by annual rainfall over 3000 mm and
covers the eastern part of the Chiriquí province and western part of the Veraguas province.
Five Almendro plantations, managed by the German forest investment company
ForestFinance (http://www.forestfinance.de/index.php?id=80&L=1) and one site of the
PRORENA project are situated close to the village Las Lajas (81°53’ W, 8°15’N), some 8 km
away from the Pacific Ocean. Another site (“Liquid Jungle Lab”) of the PRORENA project was
located near the small village Pixvae, in the Veraguas province.
Mean altitude of the plantations in Las Lajas is 50 m.a.s.l., mean annual temperature 26.7°C
and annual rainfall ranges between 3000 to 3500 mm with a distinct dry period of 4 months
from January until April. Rainfall and mean annual temperature are in the same range at the
46
RESULTS
Liquid Jungle Lab, but soils were Nitisols, which are considered to be among the most
productive soils of the humid tropics (WRB, 2007).
Table 14: Growth of Almendro on the PRORENA plots “Las Lajas “, SIGR 7, AGCL 1
Plantation
Las Lajas - B19
Las Lajas - B20
Las Lajas - B21
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
0.2
2
-
0.4
-
-
1111
1.2
14
-
1.4
-
-
1111
2.0
24
2.8
3.4
0.1
0.1
703
4.8
58
4.7
5.9
0.2
0.4
388
0.3
4
-
0.6
-
-
1111
1.2
14
-
1.4
-
-
963
2.1
25
2.5
3.5
0.1
0.1
944
4.8
58
5.7
6.4
0.6
1.4
537
0.3
4
-
0.4
-
-
1111
1.2
14
-
1.8
-
-
796
2.1
25
3.6
3.8
0.2
0.3
796
4.8
58
11.8 9.1
2.2
8.0
537
PRORENA plots always followed the management scheme (e.g. spacing of 3 x 3 m) as
described by Wishnie et al. (2007). Blocks at the “Liquid Jungle Lab” represent topographical
units (B1: lower terrace; B2: slope; B3: upper terrace), although in “Las Lajas” the terrain is
flat on all plantations. On the “Liquid Jungle Lab” plots, top height growth was the best in
block 1 (B1) that resembled a lower terrace, while height growth in the blocks on the slope
or upper terrace was inferior.
The three blocks of the PRORENA project in “Las Lajas” are situated in ForestFinance
plantations, but were not actively managed by ForestFinance. Top height on the PRORENA
plots in Las Lajas varied considerably and was the highest in Block 21 (B21) with 9.1 m at age
4.8 years and the lowest in block 19 (B19), where trees were around 3 m smaller at the same
age.
47
RESULTS
Table 15: Growth of Almendro on the PRORENA plots “Liquid Jungle Lab “, SIGR 7, AGCL 1
Plantation
Liquid Jungle Lab - B1
Liquid Jungle Lab - B2
Liquid Jungle Lab - B3
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
0.2
2
-
0.5
-
-
1093
1
12
1.6
2.2
-
-
722
2
24
3.4
4.0
0.3
0.4
722
0.2
2
-
0.5
-
-
1111
1
12
1.9
2.3
0.1
0.1
1111
2
24
4.1
3.1
0.6
1.0
1019
0.2
2
-
0.5
-
-
1111
1.0
12
1.9
2.3
0.1
0.1
1093
2.0
24
4.1
3.1
0.6
1.0
1074
Management on the ForestFinance plantations was more profound than on all other
Almendro plantations.
This company uses predominantly native species and aims to create functional forest
ecosystems. As part of their ecological forestry techniques not all of the existing vegetation
is removed, during the establishment of the plantations. Valuable old-growth trees remain
on the plantations and grasses are removed only in the planting lines, but not in-between
the planting rows, like on most of the conventional timber plantations. On the plantations
“Los Monos” and “Pampanillo” organic fertilizer was applied in the first 3 years. This fertilizer
contained chicken droppings, rice husks, saw dust and ash.
Trees were planted in small blocks or sometimes single-lines, in pure and mixed stands. In
“Los Monos”, Almendro was planted in a pure block with 6 x 6 m spacing. In “Los Rios 1” and
“Los Rios 2” tree were spaced 5 x 5 m, while the spacing in “Los Rios 3” was 4 x 5 m. In
“Pampanillo” data was collected on a PSP in a mixed block, containing Almendro planted in a
3 x 5 m spacing together with Bombacopsis quinata. In a second block in Pampanillo, which
was pure and planted 5 x 5 m, another TSP was established.
48
RESULTS
Table 16: Growth of Almendro on the ForestFinance plantations, SIGR 7, AGCL 2
Plantation
Los Monos
Los Rios 1
Los Rios 2
Los Rios 3
Pampanillo (3x5)
Pampanillo (5x5)
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
1.5
18
5.0
7.3
0.4
1.0
350
2.5
30
6.3
7.5
0.7
2.2
350
3.5
42
9.3
9.4
1.4
5.6
350
5.5
66
11.8 11.3
2.4
11.3
350
7.6
91
17.2 15.0
4.9
30.1
350
9.5
114
20.1 16.9
6.7
47.1
350
12
144
24.0 21.0
9.1
78.9
350
2.5
30
4.4
5.0
0.3
0.5
5
3.6
43
6.0
6.3
0.4
1.0
425
5.7
68
8.8
9.1
1.1
3.6
425
7.8
94
12.2 11.9
2.4
11.5
425
10
120
15.0 14.5
3.6
20.6
400
3.5
42
3.2
4.1
0.1
0.1
350
5.3
64
4.7
5.4
0.2
0.4
350
6.8
82
7.8
7.7
0.5
1.6
300
8.8
106
9.8
9.6
0.8
3.0
300
2.5
30
1.5
1.9
0.0
0.0
475
4.3
52
2.2
2.6
0.1
0.1
450
5.8
70
4.3
5.6
0.2
0.5
375
7.8
94
6.6
7.1
0.6
1.7
375
9.8
118
9.9
12.6
1.3
6.5
375
4.5
54
3.2
5.8
0.1
0.3
400
6.3
76
13.7
9.6
3.0
11.9
400
7.6
91
17.3 14.3
5.4
31.6
400
12
144
24.5 20.8
7.4
65.1
225
11.9
143
23.1 13.1
11.7
66.2
495
49
RESULTS
Both plots had been established in 1997, but Almendro in the pure plot had larger crowns
and generally lower tree heights. The difference in top-height to the mixed plot with a
denser spacing was 7 m while the top-diameters rather similar.
In the widest spacing of 6 x 6 m in “Los Monos” however, trees were the highest. These trees
grew in a wide spacing, but ground competition was high in the early years, due to
surrounding vegetation, such as bushes and grasses. Trees were liberated when surrounding
vegetation started to suppress the trees´ growth
Based on a rapid visual soil assessment it can be said that soils in “Los Monos” were sandy
loams, with good drainage, low stone content and high organic matter content. In
“Pampanillo” soils had been clayey, organic matter content was lower and drainage
appeared to be lower on the plot with 5 x 5 m spacing compared to the plot with 6 x 6 m
spacing.
Negative border effects were observed in all plantations in Los Rios, as the surrounding trees
often were Terminala amazonia, which mostly grew higher than Almendro. No thinning of
these trees took place and growth of Almendro was therefore hindered in some cases.
4.1.8 Site group 8, PA
This site group with the overall driest climate, an annual rainfall of less than 2000 mm,
contains the two experimental plantations “Rio Hato” and “Los Santos” from the PRORENA
project.
The driest site of this present study is the plantation “Rio Hato” at the Pacific coast of
Panama. This region has a distinct dry period of 6.7 dry months per year and an annual
rainfall of 1107 mm. Soils are shallow, nutrient poor and variable in texture, generally sandy
or silty clays (Wishnie et al., 2007).
50
RESULTS
“Los Santos” is the second driest plantation of this study, 5.2 dry months and a mean annual
rainfall of 1946 mm. Soils are tropical Alfisols with high concentration of P, Ca and Mg and
rich compared to all other PRORENA plantations (Wishnie et al., 2007).
Table 17: Growth of Almendro in “Los Santos”, SIGR 8, AGCL 1
Plantation
Los Santos - B7
Los Santos - B8
Los Santos - B9
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
1.3
16
-
1.4
-
-
630
1.9
23
2.1
2.2
0.1
0.1
370
3.2
38
4.4
4.6
0.3
0.6
370
4.0
48
5.6
6.2
0.5
1.1
352
5.8
70
6.2
6.9
0.6
1.8
352
1.3
16
-
1.6
-
-
481
2.0
24
2.2
2.6
0.1
0.1
407
3.3
40
4.8
5.2
0.4
0.7
407
4.3
52
6.0
6.7
0.6
1.6
407
1.2
14
-
1.5
-
-
722
2.3
28
2.8
2.9
0.2
0.2
703
3.1
37
5.1
5.2
0.5
1.0
500
4.3
52
6.8
6.7
0.9
2.4
500
Mortality of “Rio Hato” was extremely high and after 6 years only 56 trees per hectare
remained in Block 4. In Block 5 and 6 all trees died before, indicating that Almendro in “Rio
Hato” does not perform well. The overall growth was better in “Los Santos” and mortality
was lower in comparison to “Rio Hato”.
Nevertheless, with a mortality that reached more than 50% after 4 years, this site cannot be
considered suitable for Almendro.
51
RESULTS
Table 18: Growth of Almendro in “Rio Hato”, SIGR 8, AGCL 1
Plantation
Rio Hato - B4
Rio Hato - B5
Rio Hato - B6
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
1.3
16
-
1.0
-
-
870
1.9
23
-
1.6
-
-
667
3.1
37
-
1.7
-
-
278
4.3
52
-
1.9
-
-
203
5.8
70
-
1.5
-
-
56
1.0
12
-
0.9
-
-
704
2.0
24
-
1.1
-
-
333
3.2
38
-
1.3
-
-
92
4.3
52
-
1.1
-
-
37
1.1
13
-
0.9
-
-
778
2.0
24
-
1.3
-
-
352
3.3
40
-
0.8
-
-
19
4.1.9 Site group 9, PA
The PRORENA sample plots in the Soberania National Park, located in the Panama Channel
Region, form site group 9. Soberania is the only plantation on the Caribbean side of Panama.
Soils in this region belong to the Ultisol order and the climate is characterized by 4.1 dry
months per year and 2226 mm mean annual rainfall.
Top height development was better than in SIGR 8 and comparable to the development in
SIGR 7, although mortality was high compared to all other sites as around 50% of all trees
died in the first 6 years. Only SIGR 7 had a higher mortality. Reasons for this high mortality
could be ground competition with exotic grasses that have invaded abandoned agricultural
lands in the Panama Channel Region for decades. Soberania has not been farmed for 10
years and was dominated by the exotic invasive grass Saccharum spontaneum that
aggressively competes with regenerating tree seedlings preventing natural forest
regeneration (Wishnie et al., 2007).
52
RESULTS
Table 19: Growth of Almendro in SIGR 9, AGLC 1
Plantation
Soberania - B1
Soberania - B2
Soberania - B3
Years Months
d50
h50
G
V
Stocking
(cm)
(m)
(m² ha-1)
(m3 ha-1)
trees ha-1
1.0
12
-
1.2
-
-
926
2.0
24
3.3
3.4
0.3
0.4
907
3.3
40
5.7
6.7
0.6
1.4
556
4.2
50
7.0
8.0
0.9
2.5
537
5.8
70
9.3
8.7
1.3
4.1
537
1.0
12
-
1.1
-
-
741
2.0
24
2.8
3.1
0.1
0.1
741
3.0
36
5.1
5.2
0.4
0.8
556
4.3
52
7.1
9.6
0.8
2.4
556
5.8
70
10.9 9.5
1.4
4.8
481
1.1
13
-
0.9
-
-
777
2.0
24
2.1
2.3
-
0.04
722
3.3
40
3.5
3.9
0.2
0.3
537
4.3
52
4.9
5.5
0.3
0.6
500
5.8
70
7.4
7.2
0.6
1.6
500
4.2 Stand characteristics of Almendro plantations
Stand characteristics on all 36 Almendro plantations were very diverse, due to the
heterogeneity of the stands. Spacing and management varied, consequently the number of
stems per hectare and their respective diameter distribution differed even in plantations of
the same age. For every site group, characteristic plantations from mostly AGCL 2 and 3
were selected. For Panama, only site group 7 can be presented as plantations in all other
SIGR were too young.
Few plantations, which demonstrate the great variety in stem diameter distribution and
have similar spacing, are described in the following chapter 4.2.1 and Appendix 2. Their
respective stand height curves are presented in chapter 4.2.2 as well as in Appendix 3.
53
RESULTS
4.2.1 Stem diameter distribution
The only stand that received regular thinning was “Santa Cecilla” in SIGR 1 (figure 2). With an
age of 7.8 years it still belongs to AGCL 1, but for the demonstration of the effect of thinning
it is shown below.
Figure 2: Stand diameter distribution in “Santa Cecilla” with 7.8 years, 3 x 3 m spacing, regular thinning, SIGR 1,
AGCL 1
In two thinnings, 120 trees per ha were removed in 2006 and another 200 trees per hectare
in 2008, as described in chapter 4.1.1.
Trees of the smaller diameter (6 - 14 cm) classes are rare and more than half of the total
stems per hectare present at age 7.8 ranges in diameter classes greater 14 cm. The total
range of all DBH’s covered 12 cm.
It should be emphasized that thinning of Almendro plantations can result in 40 trees per
hectare with diameters in-between 18 to 20 cm after less than 8 years.
“Buenos Aires” in STGR 3 (figure 3) is unthinned and covers a DBH range of 20 cm (6 - 26 cm)
at age 14.8. After half of the assumed rotation time of 25 years has passed already, more
than 40 trees with DBH’s smaller 6 cm can still be found. These trees have no commercial
value. On the other hand, 41 trees of the largest diameter class (24 – 26 cm) are present in
“Buenos Aires” as well.
54
RESULTS
Figure 3: Stand diameter distribution in “Buenos Aires” with 14.8 years, 3 x 3 m spacing, no thinning, SIGR 3,
AGCL 2
The widest diameter range was found in “La Bomba” in SIGR 4 (figure 4). With an age of 17.3
years, 30 trees per hectare were smaller 6 cm, while 30 other trees measured 30 cm in DBH. A
similar situation was found in “Cope San Juan” (SIGR 3, age 18.4, see Appendix 2). The dominant
diameter class in “La Bomba” was the range 10 to 12 cm with 120 trees.
Figure 4: Stand diameter distribution in “La Bomba” with 17.3 years, 3 x 3 m spacing, no thinning, SIGR 4,
AGCL 3
The oldest plantation of this study, the “Canadian trial”, has been established in a 2 x 2 m
spacing and showed the following DBH distribution after 24 years without any thinning
interventions.
55
RESULTS
Figure 5: Stand diameter distribution on the “Canadian Trial” with 24 years, 2 x 2 m spacing, no thinning, SIGR
4, AGCL 3
DBH of all trees was larger 20 cm and 102 trees with DBH’s between 38 and 40 cm are
available on such sites with little management.
4.2.2 Stand height curves
Stand height curves (SHCs) have been developed to describe the stand structure, in
particular the relationship between diameter and height growth of selected Almendro
plantations.
Diameter and height were plotted in a scatter diagram and fitted to a SHC using the
Michailoff function (chapter 3.7). Parameter estimates and statistical data for all SHC are
listed in Appendix 3.
Steep curves in young ages indicate rapid height growth, but because of the retention of a
low numbers of small individuals, older curves rather showed an “extension” than a “shift”
to the right. In thinned stands, where smaller individuals are normally removed, curves shift
more to the right while moving up with increasing age.
“Cope San Juan” is a typical example of a plantation of AGCL 3 in SIGR 3. The stand
development from age 2.8 until age 18.4 is illustrated below.
56
RESULTS
Figure 6: Fitted Michailoff stand height curves. “Cope San Juan”, 18.4 years, 3 x 3 m spacing, no thinning,
SIGR 3, AGCL 3
Figure 7: Fitted Michailoff stand height curve and observed values. “Canadian Trial”, 24 years, 2 x 2 m spacing,
no thinning, SIGR 4, AGCL 3
57
RESULTS
The typical near flat and linear behavior of SHC for old plantation was observed on the oldest
Almendro plantation of this study. The fitted Michailoff curve and observed values are
shown in figure 7.
How SHC develop on poor sites became apparent in “San Juan” in SIGR 6 in figure 8. The
diagram was adapted for better clarity, as the SHC lie on top of each other. Height growth
and diameter growth for most of the smaller trees was arrested and only a small number of
dominant trees grew in diameter and height, thus extending the SHC to the right without
shifting up. The arrows in the diagram mark the range of the SHC at different ages.
Figure 8: Fitted Michailoff stand height curve for D. panamensis in “San Juan” in a mixed species plot together
with A. hunsteini, E. deglupta and S. macrophylla, age 6.5 years, 5 x 5 m spacing, no thinning, SIGR 6, AGCL 1
Stand height curves for all other SIGR are listed in Appendix 3.
4.3 Growth dynamics of Almendro
The growth pattern of Almendro was analyzed by focusing on the MAI in top height and top
diameter. Often MAI refers to stand mean values or volume per hectare, but in the present
58
RESULTS
study the resulting values would not have allowed a comparison between the Almendro
plantations as they all had different silvicultural management schemes, initial spacing and
current stocking, see chapter 3.3.
4.3.1 Mean annual increment of Almendro
Figure 9, indicates the fast initial growth that Almendro can achieve. Trees of the highest
diameter class are able to grow in average up to 3 m in top height per year, in the first 5
years after planting. This rapid development slows down until age 10 from which the MAI in
top height ranges in-between 1 to 2 m/year. The oldest plantation of this study (“Canadian
Trial”) had a MAI in h50 of 1.4 m/year.
Figure 9: MAI in top height (h50) of D. panamensis in timber plantations across CR and PA
This growth pattern seems to be similar to the top diameter development (figure 10). MAI in
d50 is also accelerated in the first years and slows down until age 10. Top diameter growth
can reach up to 3.5 cm/year at age 4.8, for example on the plantation “Puente Hamaca” in
SIGR 4 and 1.7 cm/year at age 24 on the “Canadian Trial”. However, one needs to bear in
mind that dominating influences for diameter growth are stocking, spacing and thinning
(Evans and Turnbull, 2004).
59
RESULTS
Figure 10: MAI in top diameter (d50) of D. panamensis in timber plantations across CR and PA
4.3.2 Top height growth
Most growth records originated from younger plantations (AGCL 1) and only few are
currently available for plantations of AGCL 2 or 3. The mean age of all growth records was
8.8 years, which is rather low considering a rotation time of 25 years.
Still, trends in growth are obvious and based on these observed values lines can be
computed to represent the data.
On one hand, sites can be classified based on the observed top height / age relation (chapter
4.4) and on the other hand the observed trend in top height growth can be projected for a
certain period to see how the top height might develop, for example until the end of a
rotation period as demonstrated in chapter 4.5.
In figure 11, measured top heights of all plantations are plotted against age
60
RESULTS
Figure 11: Top height development of D. panamensis over age
4.4 Preliminary site indices for Almendro
For the classification of Almendro plantations as well as to improve yield estimations, site
indices were derived through statistical curve-fitting procedures. This approach is called the
“guided curve method” and for the development of anamorphic top height curves the
Chapman - Richards function (Equation 3) was used. Based on the observed top-height
values, the index age was set to 15 years and five site index – classes in 2 m intervals were
defined after the visual assessment of trends in the observed top heights, see figure 11.
Each site index class covers a range of 1.99 m, e.g. the highest class (SI 25) covers the range
from 24 to 25.99 m of top-height at index age 15, and accordingly SI 17 covers the range 16
to 17.99 m.
61
RESULTS
Close to the index age, top height measurements with a distinctive increment were
available. Accordingly, the Chapman-Richards model was constrained that predominant
height equals the observed top height values at the previously defined index age.
First, using the Microsoft Excel Solver function, the parameter c was estimated after
transposing the Chapman-Richards equation accordingly (model 1). Once the coefficients c
and d are known, the Chapman-Richards equation can directly predict the site index curves
at a given age. Therefore, the previously estimated parameter c was inserted in model 2 to
receive parameter d to guide the curve through a second point. The site index curves were
then guided at age 10 and index age 15 by setting parameter t to 15 and using the previously
calculated parameter d at age 10 (d10), from model 2. The respective SI - curve were then
calculated with model 3.
Model 1:
Where: Hi = top height at index age, h1 = presumed top height at age 10, h2 = presumed top height at rotation
age 25 and c = parameter
Model 2:
Where: dt = parameter d at age t (guiding point was set at age 10, thus t=10), h1 = presumed top height at age
10, h2 = presumed top height at rotation age 25 and c = parameter
Model 3:
Where: t= index age 15, dt = parameter d at age 10 (calculated with model 2), h1 = presumed top height at age
10, h2 = presumed top height at rotation age 25 and c = parameter
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RESULTS
For example, the curve for SI-17 was calculated with the equation below:
Parameter estimates and attributes of all preliminary Almendro site index curves are listed in
Appendix 4. The resulting site index curves, together with all top-height measurement of
each plantation are illustrated below:
Figure 12: Site index curves for 5 different site qualities in CR and PA
Most of the observed values are covered by the range of the site index curves, yet some top
heights range below the lowest SI-class (SI-17) and above the highest SI-class (SI-25)
4.5 Top-height projections
Projections of top height to a rotation length of 25 years were developed using the Chapman
- Richards model (Equation 3), to show how Almendro plantations might develop until the
63
RESULTS
end of a rotation period and to compare their trend with the site index classes. Most of the
Almendro plantations were too young for predictive modeling or did not have a sufficient
amount of consecutive measurements. Therefore, only the growth of plantations in AGCL 3
could be projected. These plantations were situated in SIGR 3 and 4 and the resulting growth
projections were then compared with the previously developed site index curves.
It became necessary to constrain the model parameters a and b in order to converge on a
proper solution. The model did not return a solution of 1 in each case for parameter b,
causing curves to start in different points. Parameter b was for that reason constrained to
equal 1 and additionally parameter a was constrained to be equal or smaller than 40 to
obtain realistic growth projections on the long run (see chapter 5.2.1). All model parameters
of the growth functions for the six plantations of AGGR 3 are listed in Appendix 4.
Projections for all plantations showed polymorphic-nondisjoint curves indicating the rapid
top height growth in the first years that began to reduce after 10 to 15 years. The plantation
“Oscar Rodriquez” showed reduced top height growth already after 5 years and finally
reached the same top height like the plantation “Los Almendros” at the end of the rotation
period. Overall, projected growth for “Los Almendros” was the lowest.
Plantations from SIGR 4 grew better than plantations from SIGR 3 according to the
projections. The “Montagnini” plantation, where a thinning trial took place, developed the
best. The unthinned areas of this scientific plantation outperformed the thinned areas in the
first 7 years, until a shift in top height growth took place. From that point, top height growth
of the thinned areas was clearly higher in the following years and the difference between
the projected top height of thinned and unthinned areas at the end of the rotation period
was almost 5 m, according to the projections.
64
RESULTS
Figure 13: Top height growth projection in comparison with site index curves for six plantations in AGCL 3
In comparison to the site index curves, two plantations ranked in the lower classes, two in
the middle and two in the upper site index classes. The curve of the “Montealegra”
plantation reflected the development of site index class 21 almost exactly.
However, other plantations seem to follow the development of the site index curves in the
first years and deviate later on. As a consequence they typically switch to the next lower site
class. “Cope San Juan” even started in SI 25, switched in-between year 5 to 10 to SI 23 and
ended finally in SI 21.
Nonetheless, all projected top height curves stayed in the respective site index class they
had at index age 15.
65
DISCUSSION
5. DISCUSSION
In this chapter, the presented results are critically discussed in reference to other studies.
This present study is of explorative character and therefore comparison is drawn to tropical
forest ecology and other commercial timber species, as no publications exist regarding
Almendro in older timber plantations. As a final point, limitations of the study are identified
and further recommendations for future research are given.
5.1 Data basis
Through the monitoring of Almendro plantations in Costa Rica and Panama, important
information about the growth of this tree species was generated by both plantation owners
and scientist. For this study a vast data pool was established based on these existing, but
also on new datasets. However, measurement data originated from plantations that were
treated and monitored in various ways. The data pool was prepared for data analysis as
described in chapter 3.3, yet even after removing false values and outliers, some unclear
developments occurred on few timber plantations, which could not be verified afterwards.
PSPs could not be restored in some cases and the established TSPs did not succeed in
describing the stand density in two cases, in particular on the “Montagnini” plantation,
leading to unreliable volume values from these plots. Moreover, in the provided dataset of
the same plantation, an unrealistic drop in the stocking took place at age 9.9 from 1994 to
863 trees per hectare. This event would comply with a sudden mortality of more than 50%
and does not match the density per hectare of 1875 trees / ha-1 that was recorded
personally on a TSP in 2009, almost 9 years later.
It also needs to be mentioned that border effects were observed on PSPs, especially on
plantations where small pure patches of Almendro had been mixed with other species in
blocks or lines, such as the Los Rios plantations in Panama, SIGR 7. Positive border effects
were filtered out during the data preparation phase, but negative border effects have not
been excluded from the data set as they seem to be common in Almendro line mixtures or
66
DISCUSSION
small sized block mixtures, where no thinning interventions of the surrounding stands have
taken place.
To give details about the great variety of the underlying data set a statistical analysis
(regression and correlation) was tried, but overall sample size and the distribution of the
measurements was suboptimal as most of the plantations were too young, thus not allowing
a precise statistical description of variations or influencing site factors for the whole dataset.
Data for young Almendro plantations in particular at 2 years of age, was exceptionally
frequent, as shown in table 20. Using a reference age of 2 years for statistical comparisons
would not have made any sense. Total number of measurements for each age and
precipitation group is given in the following cross-table.
Precipitation Group
Age
1000 – 1999 2000 – 2999 3000 – 3999 >4000
(mm)
(mm)
(mm)
(mm)
N
0
1
2
3
4
5
6
7
8
9
10
11
12
15
17
18
24
6
6
7
7
7
1
3
1
1
0
0
0
0
0
0
0
0
3
3
7
6
6
5
7
2
2
0
0
1
0
0
0
1
0
6
9
13
10
11
12
9
9
9
2
3
3
3
2
1
3
0
0
1
3
3
4
1
0
3
2
0
2
0
0
2
0
2
1
15
19
30
26
28
19
19
15
14
2
5
4
3
4
1
6
1
Total
39
43
105
24
211
Table 20: Cross table with the number of available growth records at a certain age in different precipitation
groups across CR and PA
67
DISCUSSION
The situation was similar with other site parameters, such as soil type and altitude.
Furthermore, site factors could not be assessed locally on every plantation. Local
precipitation values from “Santa Cecilla” in SIGR 1 (annual rainfalls of 3649 mm in the period
from 2002 until 2006) for example, were significantly higher than shown in climatic maps of
Costa Rica (Ortiz and Cordero, 2008), where annual rainfall of 2000 - 2500 mm is given for
this region. Soil data as well originated from general maps, thus not having the precision
and accuracy of local soil samples.
5.2 The effect of site selection
Regional distinctions of top height growth have been observed and site index calculations,
the analysis of mean annual increment in top height growth, as well as observed mortality
indicate the effect that site selection can have on the growth of Almendro.
The influence of the site was already apparent when comparing MAI values of plantations in
different SIGRs in AGCL 1. The h50 MAI in the plantation “Mulas” in SIGR 6 for example was
0.8 m/yr at age 6.6, while the “Montagnini” plantation in SIGR 4 had a h50 MAI of 2.4 m/yr at
age 6.8. In the latter case, top height growth was more than three times higher as in the
plantation “Mulas”. Also mortality indicated the effect of site selection, like on the PRORENA
plantations “Rio Hato” and “Los Santos” in drier regions of Panama (annual rainfall below
2000 mm, SIGR 8) as described in chapter 4.1.8. For older plantations in AGCL 2 and all
plantations in AGCL 3, the site index curves can be used to determine the site quality since
plantations do not switch the site class anymore once they reached the index age of 15
years, as described in chapter 4.5.
In line with other publications (Pyke et al., 2001) it can be said that tropical forests show
clear patterns of spatial organization along environmental gradients, predominantly
precipitation. In addition, geologic and edaphic conditions can override the effect of
precipitation in some cases, such as acidic soils or excessively drained limestone substrates
(Pyke et al., 2001).
68
DISCUSSION
These factors need to be considered for the tree species selection before plantations get
established. By not doing so, plantations might not return the investment. Predictive
modeling and site classification, to select the best land for plantations, can have a major
influence on plantation profitability according to Evans and Turnbull (2004).
Almendro naturally exists in areas with mean annual rainfall ranging from 3500 to 5000 mm
and in altitudes from 20 to 500 m.a.s.l, as mentioned in chapter 2.1. In particular plantations
in SIGR 6 and 8 have been established outside this natural range of Almendro and especially
these plantations performed the poorest. SIGR 6 was higher than 600 meters and SIGR 8 was
characterized by annual rainfall lower than 2000 mm. In other site groups with annual
precipitation from 2000 to 3000 mm where the altitude corresponded with the natural
range, Almendro performed well, e.g. in SIGR 1 and 2 at the edge of the geographic range of
Almendro, or SIGR 7 with annual rainfall greater than 3000 mm on the Pacific site of
Panama, where Almendro naturally does not occur frequently.
Based on this observation it can be said that Almendro needs at least 2000 mm rainfall per
year to grow satisfactorily and results from regions with lower rainfalls do therefore not
represent the species potential. Whereby, in tropical regions the distribution of the rainfall
probably might be more important than the actual amount (Vanclay, 1992).
Effects of the soil cannot be assessed as soils have not been sampled for each plot and soil
data originated from large scale soil type mapping, not allowing an accurate comparison
between sites. Most of the plantations were established on Ultisols and the few plantations,
which were established on other soil types, were subject to other influences such as soil
compaction due to grazing. Delgado et al. (2003) compared the growth of Almendro on soils
of the Ultisol and Inceptisol order and highlights that Almendro performed the best on sites
with an Ultisol soil profile. However, based on the general characteristics of the soil types it
can be argued that plantations of Almendro grow best on richer soils with good drainage in
general, for instance the Fluventic Dystropepts in La Selva (SIGR 4). Anyhow, Almendro
showed good results on poorer soils with high acidity such as Ultisols. This can be considered
69
DISCUSSION
a great advantage over exotic species, such as Tectona grandis, which need fertile soils to
perform well (Butterfield, 1994).
Taking the natural distribution of Almendro into account, Chun (2008) stated that
environmental factors exists that predict high densities of Almendro in natural forests, such
as elevations between 45 – 125 m.a.s.l and soils of the Humult, Aquent, and Tropept
suborder. It can be assumed that Almendro plantations will thrive well on these sites as well.
5.2.1 Site index calculation and top height projection
It has to be remembered that the growth observations, which were used for the
development of the site index curves, covered a wide range of sites, but plantations were
very heterogenic, young and not evenly distributed along every SIGR. Some SIGRs for
instance contained only young plantations of AGCL 1. According to the data set it would
make sense to set the index age to an earlier age, as many observations are available, but
index age 15 was chosen instead for of several reasons.
Brack (2000) notes that for the selection of the index age, the index age should be greater
than eight years as factors of the site have to express themselves. Accordingly, a good
criterion for the selection is 2/3 of the rotation age and the selected age of 15 is close to this
criterion (Brack, 2000). Other publications made use of index age 15 as well, such as Cháves
and Mora (2002), who additionally compared their site index model for Bombacopsis
quinata on plantations in the Guanacaste Region of Costa Rica with the one of Navarro
(1987), who used the index age 10 for the same species and region. The comparison showed
that site index curves, developed with such a young index age of 10 years, tend to overstate
the overall growth as they project the increased height growth in young stands for the entire
rotation period. For the same reason, top height projections in chapter 4.5 were only
developed for plantations in AGCL 3.
Publications from e.g. De los Santos-Posados et al. (2006) underline the limitations that the
Chapman-Richards function can have. They used the function to produce height growth
70
DISCUSSION
curves for Terminalia amazonia in Costa Rica and discovered that the model shows good
statistical fit, but overestimated the height development at the intermediate age range of 12
to 20 years.
Nevertheless, given its flexibility, the Chapman-Richards model was also used to create the
site index curves for Almendro and in accordance with other publications (Montero et al.,
2001; Somarriba et al., 2001; Montero and Kanninen, 2003; Bermejo et al., 2004; Upadhyay
et al., 2005), the “guided curve method” was used. This approach is wide spread in tropical
forestry and site index curves for other commercial tree species in Costa Rica and Panama
were developed by the same method.
Apart from limitations of the developed site indices given by varying management practices
and seed sources, deviations from the predicted growth pattern may occur due to:
-
Climatic fluctuations
-
Changes in atmospheric nitrogen deposition
-
Elimination of dominant heights due to disease or thinning
All site quality indices and growth projections should be validated as soon as stands of AGCL
1 have reached age 15, because significant differences in their development are not
foreseen. It might become necessary to develop another set of site-index curves that is able
to describe their growth dynamics.
As a final point, it must be mentioned that more sophisticated models are used in temperate
forests of industrialized countries, but they have not found their implication in tropical
forestry yet (Sloboda, 1972; Zeide, 1993; Pretzsch, 2009), see chapter 3.5.
5.2.2 Frequency of site index classes
The preliminary site indices were used to associate the last observed top height of each
plantation with a particular site index class. Overall, site index class 19 was the most
frequent, followed by SI 17 and SI 25.
71
DISCUSSION
The frequency of site index classes and age classes in every SIGR is given below:
Table 21: Frequency of site index classes and age classes in each site group
SIGR
AGCL
Frequency of site index classes
1
2
3
1
3
-
-
-
1
1
1
-
2
1
1
-
1
-
1
-
-
3
-
3
3
2
2
2
-
-
4
4
2
4
-
-
1
2
7
5
1
2
-
-
-
-
-
3
6
4
-
-
3
1
-
-
-
7
6
-
-
3
3
-
-
-
8
3
-
-
1
2
-
-
-
9
6
6
-
3
5
2
2
-
13
14
7
5
10
Total frequency of SI-classes
SI-17 SI-19 SI-21 SI-23 SI-25
The table shows that it is impossible for most of the SIGRs, to classify their suitability for
Almendro plantations, if the classification is solely based on the site index classes. On the
one hand, a clear trend in site index class distribution can be observed only in SIGR 4, 5 and 9
and on the other hand, most plantations were too young to associate them with a particular
site index class, as young plantations tend to switch to the next lower site index class while
maturing, see chapter 4.5. A trend that was also observed for Tectona grandis in Trinidad,
where height growth equivalent to that of site class I at 5 years of age, dropped to site class
II as it grew older (Lamb, 1957).
Though significant height/age relationships may not be causal, defining them still assists the
prediction of growth on similar sites and therewith aids rational decision-making on land
suitable for reforestation projects (Evans and Turnbull, 2004).
72
DISCUSSION
5.2.3 Promising regions for Almendro plantations
Taking all observations, such as MAI in the first years, mortality and the assigned site index
classes for all plantations in AGCL 3 into account, recommendations for regions suitable for
Almendro plantations, can be derived.
Performance of Almendro was clearly the best in the Atlantic lowlands of Costa Rica, in
particular SIGR 4 and 5. Also the northern zone of Costa Rica (SIGR 2 and 3), the Pacific –
Atlantic transition zone (SIGR 1) as well as the wet Pacific region in Panama (SIGR 7) showed
good results. The suitability of Soberania (SIGR 9) is given, when considering the top height
growth and natural distribution of Almendro in this region, but the high mortality levels on
the other hand, indicate that this site is not suitable for Almendro. Reasons for the poor
performance of Almendro on this site could be the presence of Saccharum spontaneum,
which aggressively competes with regenerating tree seedlings (Hooper et al., 2002; Wishnie
et al., 2007; Joo Kim et al., 2008). Balderrama and Chazdon (2005) summarized that
Almendro seedlings and sapling have generally a high survival rate and can survive in shade,
gaps and sunny sites, but Hooper et al. (2002) proved in a trial in Saccharum spontaneum
grasslands, that Almendro can be outcompeted if the grass is not mown, shaded or treated
with herbicides.
Besides suitable regions, unsuitable regions for Almendro plantations were identified as
well. In particular regions above 500 m.a.s.l (SIGR 6) and regions with annual rainfalls below
2000 mm (SIGR 7). These findings are in line with other publications (Cordero et al., 2003), in
which dry climates, elevations higher 500 m and poorly drained soils were described as
limiting factors for Almendro.
5.3 Silviculture
The stand development showed a great variety, when comparing the different management
schemes of Almendro plantations in Costa Rica and Panama. Factors that affect the
increment are the internal conditions of the tree species (genetic and physiological), external
conditions (the site) and the management, of which the most important effects on the
73
DISCUSSION
growth in plantations are determined by initial spacing and silvicultural treatments such as
thinning and pruning (Brack, 2000; Evans and Turnbull, 2004). All of these factors differed in
Costa Rica and Panama, and in most cases the management can be improved to enable
Almendro, to fully unfold its potential and to produce a mix of tree sizes for sawn timber,
veneer or poles.
At the time when most of the Almendro plantations were established, commercial seeds
were unavailable (Butterfield, 1995). Seeds have been sourced from identified seed trees
growing in natural forests in different regions of Costa Rica and Panama, and thus did not
undergo any genetic improvement or strict selection process based on experience in timber
plantations or seed orchards. Chun (2008) found four separate Almendro subpopulations,
solely in the proposed “San Juan - La Selva Biological Corridor” in Costa Rica and
correspondingly it can be assumed that the genetic variability of Almendro grown in timber
plantations is immense due to numerous seed trees in Costa Rican and Panamanian
rainforests.
The external factors affecting the growth were already discussed in chapter 5.2 and
particular focus to the silvicultural management is given in the following chapters 5.3.1 and
5.3.2.
5.3.1 Initial spacing and stand density
The observed stand density on all plantations, best explains the differences in growth as
lower density plantations yielded higher DBH, total height and tree volume in most of the
cases.
Some studies have shown a relationship between the maximum number of individuals that
can occupy a site and the average size of the individuals (Smith et al., 1997). This natural
basal area effect was also described by Pienaar and Turnbull (1973), who stated that evenaged stands with initial stocking above a certain limit, converged towards identical stand
basal area, determined by the capacity of the site.
74
DISCUSSION
On the “Canadian Trial” (SIGR 4), where the initial spacing was 2 x 2 m and no management
took place, 357 trees per hectare were found, representing the natural basal area of this site
at 24 years of age (chapter 4.1.4). The existing trees were of good form, as they first had to
grow in height to outcompete surrounding trees and could not develop any lower branches,
because of high ground competition in early years. Finally, the surviving trees did then
succeed in building up descent crowns even after heavy competition over a long period of
time, which could be explained by the fact that Almendro belongs to the canopy emergent
layer in Neotropical rainforests. Tropical ecologist emphasize that these canopy species,
usually have a high juvenile survival and a large increase in growth rates when exposed to
high light levels (Turner, 2001). Nevertheless, information on crown and stand
characteristics in response to initial spacing are not available for Almendro, but have been
published for widespread commercial tree species, for example Eucalyptus nitens (Pinkard
and Neilsen, 2003).
Top diameter on the “Canadian Trial” was close to 40 cm and it can be assumed that the
commercial value of this scientific plantation is high, also due to good form and a
commercial height over 14 m.
Nevertheless, through managing a plantation diameter growth can be increased, the wood
quality improved and rotation cycles shortened, thus increasing the overall financial yield of
the plantation (Lamprecht, 1986; Piotto et al., 2003; Evans and Turnbull, 2004). Only by
performing intensive and timely silvicultural interventions, success in the management of
plantations of tropical tree species can be achieved (Kanninen et al., 2004).
5.3.2 Thinning and pruning
One thinning trial in the Atlantic lowlands of Costa Rica included Almendro (Piotto et al.,
2003) with the results that thinning in pure- and mixed stands does have positive effects all
in all. Diameters were larger, mean total height and basal area per tree were higher, but
stand volume and stand basal area were lower in thinned plots compared to unthinned
plots. Although, thinning may lead to losses in wood volume, the loss of volume is generally
75
DISCUSSION
compensated by superior wood quality and value (Espinosa et al., 1994). Other authors
showed that if the plantation density is not reduced crown recession, reductions in diameter
growth and increases in height/diameter rations are the result. Even reduction in height
growth, including dominant height, can appear within a short period of time (Galloway et al.,
1996).
According to Evans and Turnbull (2004), thinning would help to:
-
Reduce the number of trees to have more space for the development of the
remaining ones, thus encouraging diameter growth to reach a usable size sooner
-
To remove trees of poor form (crooked, forked, etc.) to concentrate future increment
on the best trees
-
Favor the most vigorous tress of good form, which will make up the final crop
-
Provide an intermediate financial return from sale of thinnings
Even delayed thinnings can favor the growth, as shown for Vochysia guatemalensis,
Hyeronima alchorneoides, Terminalia amazonia, and Calophyllum brasiliense in native
species plantations in Costa Rica (Jacobs et al., 2005).
This study did not assess single tree quality, but visual observations showed that Almendro
tends to low bifurcation if spacing is too wide, especially if trees are planted in line mixtures.
Lower spacing and timely pruning interventions could help to obtain better tree form. It was
observed that Almendro mostly builds branches with included bark. To assists the healing of
the pruning scar, the pruning cut should be done according the attachment of the branch as
described by Dujesiefken and Stobbe (2002). Finally, pruning has to be considered together
with the initial spacing and thinning regime (Evans and Turnbull, 2004). On the long run, a
pruning regime similar to the one for Tectona grandis (Víquez and Pérez, 2005) should be
developed for Almendro as well.
76
DISCUSSION
The benefit of silvicultural management is evident and based on the own observations on
timber
plantations
across
Costa
Rica
and
Panama,
provisional
management
recommendations will be given for three management scenarios.
The good performance of Almendro in mixed species plantation and the general advantages
of species mixtures such as diversified timber products, increased biodiversity and soil
protection were described by several authors (Petit and Montagnini, 2004; Petit and
Montagnini, 2006; Redondo-Brenes and Montagnini, 2006), but given the great number of
possible species mixtures, recommendations are only given for pure plantations.
5.4 Timber production on Almendro plantations
Almendro outsells every other tree species on the Costa Rican timber market (Rodriguez and
Chaves, 2008; Grethel and Norman, 2009), but the situation on the Panamanian timber
market is unclear, because of unavailability of data on timber prices. Wood prices for
Almendro in Costa Rica however exhibit a steady increase and are not as susceptible to
heavy fluctuations like the prices for Teak (Grethel and Norman, 2009). Up to the present
day, timber from Almendro plantations has never been sold, as plantations did not receive
any commercial thinnings or intermediate- or final harvests. The high prices in Costa Rica are
obtained for Almendro from natural forests and it is not certain, what prices Almendro from
timber plantation will achieve on local or international timber markets in the near future.
A first provisional silvicultural regime, with the main goal of producing high quality timber
for different uses, such as poles, sawn timber and veneer was developed for Almendro. The
focus is therefore on maximum tree growth and tree quality, instead of maximum volume
growth as in carbon forestry projects, see chapter 5.5. All recommendations are given based
on Evans and Turnbull (2004), growth records, own observation and in line with other
publications (Jiménez et al., 2002; Cordero et al., 2003; Piotto et al., 2003; Kanninen et al.,
2004; Perez and Kanninen, 2005; Víquez and Pérez, 2005).
77
DISCUSSION
Almendro plantations should be established with an initial spacing of 3 x 3 m, thus resulting
in 1111 trees per hectare. A selective thinning method is recommended, following the
proposed thinning regime (table 22).
Table 22: Proposed thinning regime for Almendro in timber plantations
Intervention
Age
Thinning rate*
1st thinning
3-4
2nd thinning
Stocking**
Intensity
Potential products
889
Light
poles
889
622
Moderate
poles/ sawn timber
40%
622
249
Heavy
sawn timber
50%
249
124
Before
After
20%
1111
8-9
30%
3rd thinning
14-15
4th thinning
19-20
Very heavy sawn timber/ veneer
* % of the standing trees, ** trees / ha-1
In the first thinning dead, diseased, suppressed and trees of poor form should be removed
in-between age 3 and 4. This thinning should be followed directly by a low pruning up to a
height of 3 m in order to obtain a high amount of knot free timber on the lowest stem
section. Pruning should include all trees to improve the overall timber quality.
The first light thinning and the low pruning should then be followed by a moderate second
thinning from below at age 8 to 9, where suppressed and sub-dominant trees should be
removed. If markets are available also co-dominant trees may be removed additionally.
Afterwards, a second pruning should be conducted up to a height of 6 meters. By
implementing a medium pruning the value of all trees is increased once more as trees that
will be removed in the next thinning, might already have diameters suitable for sawn timber.
At age 14 to 15 trees can be pruned for the third time. The thinning should be heavy as the
plantation reaches an age where marketable tree sizes are very likely. All sub-dominants and
co-dominants trees can be removed in a thinning from below. If the removal of some
dominant trees does not result in permanent gaps, thinning can go more into the crowns to
78
DISCUSSION
remove some dominant trees for commercial uses. After that, the selection and marking of
future crop trees can take place.
The last thinning at age 19 to 20 should be very heavy and result in a stand that consist only
in trees of best form, with good crowns, well spaced and evenly distributed over the
plantation. Future crop trees should be liberated in this last thinning to concentrate the
growth on the best trees, before the final harvest can take place at age 25.
This proposed management scheme for Almendro has to be validated in the field and should
be optimized through thinning trials were different intensities are tested. For the beginning,
it should be sufficient to improve the quality of Almendro plantations in Central America.
5.5 Carbon forestry
The main goal of planted carbon forestry systems is the sequestration of a maximum
amount of CO2, which can be achieved through focusing management and silvicultural
interventions on maximum stand volume growth (Read et al., 2001). Tree form and quality
are of importance if timber revenues should be generated, but a low-input conservation
approach is assumed for the development of recommendations for pure carbon forestry
projects using Almendro.
All assumptions and calculations are based on the methodology of the CarbonFix Standard*
(CFS). This ex-ante standard enables plantation owners to generate verifiable offsets, which
can be traded on international voluntary carbon markets (Hamilton et al., 2009).
Other carbon standards are available as well, but the CFS is considered the one assuring the
highest quality of the generated offsets (Kollmuss et al., 2008).
*The standard (Version 3.0) can be directly downloaded on the following webpage:
http://www.carbonfix.info/chameleon//outbox/public/189/CarbonFix_Standard_v30.pdf?PHPSESSID=4bo1l5c5
pbh5gj88g93ed1p832
79
DISCUSSION
The CFS offers two calculative options to determine the future CO2-fixation, depending on
the applied silvicultural methods. These silvicultural options are selective harvesting,
conservation forest or rotation forestry. The calculations of the future CO2-fixations are
based on the mean stand volume during the first rotation period in case of rotation forestry
and the equilibrium stand volume in case of selective harvesting or conservation forests.
Recommendations given in chapter 5.4 are valid for the rotation forestry approach, but as
mentioned earlier, the conservation forests approach is assumed for pure carbon forestry
projects, meaning that no interventions are supposed to take place.
For the achievement of maximum stand volume growth in conservation forests, the initial
spacing is of high importance (Evans and Turnbull, 2004) and a spacing of 2 x 2 m is therefore
recommended. No thinnings are suggested as thinnings tend to decrease the total volume,
while increasing the single tree quality (Piotto et al., 2003; Evans and Turnbull, 2004).
This proposed management regime resembles the development on the “Canadian Trial”, as
the observed results indicate that after 24 years 356 trees can grow on one hectare with a
total stand volume of 410 m³/ha. The predefined calculation method for the amount of
sequestered carbon is part of the CFS and would result in 755 t CO2/ha when using the
numbers from the “Canadian Trial”.
The CFS provides conservative standard values if no scientific data is available. In the case of
Almendro, standard values were used for the biomass expansion factor and the root to
shoot ratio. Carbon fraction is 0.5 and C to CO2 conversion factor is 3.6666 according to the
standards´ definition.
Equation 6: CarbonFix equation
Where: TWB = total woody biomass, V = stem volume, BEF = biomass expansion factor, WD = wood density,
CF = carbon fraction, CCF = C to CO2 conversion factor, RSR = root to shoot ratio.
80
DISCUSSION
This formula is an easy to use approach for the estimation of total woody biomass, aboveand belowground. It is evident in this formula that high wood densities are a driving force for
high carbon uptake, as described by e.g. Redondo-Brenes (2007).
The results for Almendro on the “Canadian Trial” can be compared deliberately with data
from unthinned Teak plantations in Panama (Kraenzel et al., 2003). Above – and
belowground biomass was measured for 20 year old plantations and total carbon storage
was estimated to be 351 t C/ha. However, the soil stored the biggest amount of carbon, but
tree carbon storage averaged 120 t C/ha, which would equal a total amount of stored CO2 of
440 t CO2/ha, when applying the specified C to CO2 conversion factor set by the CFS.
5.6 Agroforestry
The present study includes growth records from Almendro in agroforestry systems as well
(see chapter 4.1.2 and 4.1.3). Almendro was frequently used in silvopastoral systems and
observations indicate that the species has great potential for agroforestry systems of various
kind. Observed growth in silvopastoral systems was slower than in plantations, which have
not been grazed, but with proper silvicultural management (thinning and pruning) diameter
growth and tree quality in silvopastoral systems can be encouraged. Almendro commonly
sheds leaves in dry periods and allows in general the penetration of high amounts of light to
the forest ground, thus making it an optimal species for the use in agroforestry systems
(Haggar et al., 1998; Haggar et al., 2003; Montagnini et al., 2003). Thinnings might help to
even increase this amount of light, to maintain proper light levels beneath a stand, for
deliberately growing other crops or provide vegetation for grazing. Thinning or harvesting
Almendro could supplement farmers´ income when prices for the crops or cattle are low and
intermediate returns are desired (Somarriba, 1992).
Given the natural distribution of Almendro and the fact, that Almendro does not perform
well on higher elevations, the use of this species can only be recommended for lowland
agroforestry systems, such as tree crop combinations with cacao (Theobroma cacao),
pineapple (Ananas spp.) or silvopasture and not for crops that are normally grown in higher
81
DISCUSSION
elevations, such as coffee (Coffea spp.) or highland silvopastoral systems (Beer, 1987; Beer
et al., 1997; Dagang and Nair, 2003; Haggar et al., 2003; Montagnini et al., 2003).
Finally, carbon sequestration could also be a possible benefit in agroforestry systems
(Montagnini and Nair, 2004) and the CFS for instance would even allow the generation of
tradable carbon offsets in silvopastoral systems.
82
DISCUSSION
5.7 Limitations of the present study
Some limitations have been already discussed in the previous chapters, but the main
limitations are listed below:
-
Most of the plantations were too young for a proper statistical correlation of site
factors and site factors, such as the soil were not assessed locally on all plantations
-
Permanent sample plot design was insufficient in some cases
-
Site index curves, growth projections and silvicultural recommendations are based on
data from only few older plantations any many young ones. All plantations had
inappropriate management and overall growth might therefore be understated.
5.8 Recommendations
Based on observations and results from Almendro timber plantations across Costa Rica and
Panama, the following recommendations can be given:
-
The immediate implementation of silvicultural management schemes for all stands,
especially thinning and pruning to obtain trees of good form and large diameters
-
Continuation of all measurements on all plots and reactivation of unmanaged
permanent sample plots to collect data about the performance of Almendro in
different growth stages, spacing, and mixture under various site conditions
-
Establishment of thinning trials for early interventions and delayed thinnings
-
Establishment of pruning trials to develop a pruning regime
-
Assessment of the tree competition and crown development (measurement of the
trees position on plots as well as measurement of crown parameters)
-
Development of a species specific form factor
-
Development of biomass expansion factors and root to shoot ratios
83
CONCLUSION
6. CONCLUSION
The superb wood quality of Almendro pays the highest prices on local timber markets and
using this fine hardwood especially for floorings, furniture or heavy construction is
widespread. The wood that is processed in Costa Rica originates from Nicaraguan
rainforests, as the logging of Almendro is banned in Costa Rica since 2008. With diminishing
supply from natural forests, Almendro grown on plantations will gain importance. These
plantations have the potential to lower the pressure on natural forest resources if
management is optimized. In the best scenario high levels of biodiversity and endangered
species like the great green macaw (Ara ambiguus) can be protected and preserved for
future generations.
In the present study data on long-term growth of Almendro in plantations in various climatic
zones of Costa Rica and Panama was collected. Preliminary findings showed that Almendro
plantations developed the best in Atlantic lowlands of Costa Rica and good performance was
achieved in regions that are characterized by a climate with annual rainfall greater 2000 mm
and elevations below 500 m. Almendro also grew well on poor soils and showed good
performance in silvopastoral systems.
Through site classification, growth modeling and the creation of provisional silvicultural
regimes, a starting point for further improvements of the management of Almendro
plantations was set by this study.
As current plantations mature, silvicultural knowledge under local conditions should
increase, if research and monitoring is continued on existing sample plots. It is of highest
importance to reactivate abandoned permanent sample plots and to implement thinning on
all plantations, to gain knowledge about the long-term growth and the reaction of Almendro
to thinnings. Through these activities and the establishment of new sample plots, the results
from this study can be verified and further developed.
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93
APPENDICES
APPENDICES
Appendix 1 - Detailed information on sampled Almendro plantations
Institution
OTS - La Selva
ITCR /
COSEFORMA
RTT
CATIE
EARTH
Precious Woods
G. Navarro
Los Tucanes
Number
of plots
SIGR
Dominant
AGCL
Initial
spacing
Canadian Trial
1
4
3
2x2m
Haggar
1
4
2
4x4m
Montagnini
18
4
2
2x2m
Oscar Rodriquez
4
3
3
3x3m
Montealegra
4
2
3
3x3m
Los Almendros
4
3
3
3x3m
Cope San Juan
4
3
3
3x3m
Edwin Romero
1
3
2
3x3m
Olman González
1
3
2
3x3m
Buenos Aires
1
3
2
3x3m
CMECC
4
5
2
4x4m
CONCOL-00
2
5
2
4x6m
MOHEGAN
4
5
1
4x4m
CACTU
4
6
1
3x3m
Las Peñas
1
6
1
3x3m
Las Mulas (RTT)
1
6
1
5 x5
San Juan
2
6
1
5 x5
Tamara AFS
1
2
1
12 x 12 m
La Bomba
2
4
3
3x3m
Y-Griega
1
4
2
3.5 x 3.5 m
Tiro al blanco
1
4
1
3.5 x 3.5 m
Puente Hamaca
1
4
1
4x4m
Santa Cecilla
1
1
1
3x3m
Cacao
4
1
1
4x4m
Orosi
9
1
1
4x4m
Los Tucanes
2
4
1
3x4m
Plantation
94
APPENDICES
Table 23: Overview and characteristics of Almendro plantations in Costa Rica
Institution
PRORENA
ForestFinance
Number of
plots
SIGR
Dominant
AGCL
Initial spacing
Liquid Jungle Lab
9
7
1
3x3m
Rio Hato
9
8
1
3x3m
Soberania
9
9
1
3x3m
Las Lajas
9
7
1
3x3m
Los Santos
9
8
1
3x3m
Los Monos 97
1
7
2
6x6m
Los Rios 1
2
7
2
5 x5 m
Los Rios 2
1
7
2
5 x5 m
Los Rios 3
1
7
2
4 x5 m
Pampanillo
2
7
2
5 x5 m; 3 x 5 m
Plantation
Table 24: Overview and characteristics of Almendro plantations in Panama
Appendix 2 - Stand diameter distribution
Stand diameter distribution for “ Cope San Juan”, 18.4 years, no thinning, 3 x 3 m spacing, SIGR 3
95
APPENDICES
Stand diameter distribution for D. panamensis in a mixed species plot together with A. hunsteini, “ConCol”, 8.1
years, no thinning, 4 x 6 m spacing, SIGR 5
Stand diameter distribution for D. panamensis in a mixed species plot together with A. hunsteini, “CMECC”, 8.3
years, no thinning, 4 x 4 m spacing, SIGR 5
Stand diameter distribution for D. panamensis in a mixed species plot together with A. hunsteini, E. deglupta
and S. macrophylla, “San Juan”, 6.5 years, no thinning, 5 x 5 m spacing, SIGR 5
96
APPENDICES
Stand diameter distribution for “Los Monos”, 12 years, no thinning, 6 x 6 m spacing, SIGR 7
Stand diameter distribution for “Pampanillo”, 11.9 years, no thinning, 5 x 5 m spacing, SIGR 7
Stand diameter distribution for D. panamensis in a mixed species plot with B. quinata, “Pampanillo”, 12 years,
no thinning, 5 x 3 m spacing, SIGR 7
97
APPENDICES
Appendix 3 - Stand height curves
Fitted Michailoff stand height curves for “Santa Cecilla”, SIGR 1
Fitted Michailoff stand height curves for “Buenos Aires”, SIGR 3
98
APPENDICES
Fitted Michailoff stand height curves for “J. Haggar” with observed values, SIGR 4
Fitted Michailoff stand height curve for “La Bomba” with observed values, SIGR 4
99
APPENDICES
Fitted Michailoff stand height curve for D. panamensis, “CMECC”, SIGR 5
Fitted Michailoff stand height curve for D. panamensis with observed values, “CONCOL”, SIGR 5
100
APPENDICES
Fitted Michailoff stand height curves for “Los Monos”, SIGR 7
Figure 14: Fitted Michailoff stand height curves for D. panamensis, “Pampanillo”, SIGR 7
101
APPENDICES
Appendix 4 - Estimated Parameter values
Plantation
Age
1
2,3
3,3
Buenos Aires
4,3
7,3
14,8
Canadian Trial 24
3,3
4,3
5,2
CMECC
6,3
7,3
8,3
7,3
CONCOL
8,1
1,8
2,8
3,8
4,8
Cope San Juan 5,8
6,8
7,8
10,8
18,4
J. Haggar
14,8
La Bomba
17,3
1,5
2,5
3,5
Los Monos
5,5
7,6
9,5
12
4,5
6,3
Pampanillo
7,6
12
R²
0,43
0,83
0,92
0,80
0,67
0,90
0,98
0,84
0,81
0,61
0,64
0,67
0,48
0,46
0,53
0,63
0,86
0,84
0,79
0,68
0,76
0,72
0,62
0,11
0,83
0,89
1,00
0,49
6,33
0,68
0,62
0,74
0,66
0,72
0,77
0,72
0,34
a
3,853912121
9,095444759
11,27458549
12,97154668
14,92544283
30,36284524
35,04232114
9,459949302
10,96552761
12,43454353
14,64202281
16,69260261
20,32593057
16,65947672
23,20447389
8,85612637
12,55067033
14,87100375
18,51352662
22,01301218
23,17276213
21,19839349
25,79567891
26,47077248
30,09154572
35,10798114
20,10721905
11,36652347
13,1346891
16,75146229
20,27287996
22,97832475
28,61688328
5,601035534
11,80555215
19,35761987
26,79694279
b
Sum of least squares Sampled trees
-2,356908027
4,12
78
-4,215977709
16,34
74
-4,745733111
14,64
77
-4,804472409
49,36
77
-4,694847191
154,84
77
-10,56895767
21,53
11
-3,155333474
4,16
7
-4,161450134
40,51
135
-5,145008512
70,12
135
-4,712923607
169,03
136
-4,628358969
180,29
137
-4,766946843
205,62
136
-6,141946701
794,38
136
-5,222655425
252,22
64
-7,648951101
520,44
65
-4,208595152
8,10
49
-5,397150404
29,84
97
-5,525583647
53,04
98
-6,353061865
108,78
98
-6,738789723
262,27
97
-6,994102617
196,17
94
-5,97426213
199,71
94
-7,078052712
374,17
89
-5,380519031
27,85
10
-8,585385826
45,75
8
-13,62425784
94,44
25
-6,025172417
1,43
13
-3,862622168
20,63
14
-4,46804204
0,80
14
-6,01897672
18,79
14
-6,750115341
24,11
14
-7,730528932
17,63
14
-8,837494901
38,45
14
-0,671132027
3,36
16
-4,739939678
8,02
16
-6,918161441
17,34
16
-7,798224422
26,51
9
102
APPENDICES
Plantation
Age
1,6
2,6
3,6
4,7
5,6
6,8
7,8
1,5
4,6
5,4
6,4
Santa Cecilla
San Juan
R²
0,04
0,87
0,67
0,69
0,50
0,72
0,71
0,79
0,91
0,91
0,89
a
2,741401887
8,961041486
11,57137015
13,73261204
12,08893732
19,01150194
18,88008319
13,62941014
12,2610103
15,13156374
15,13156374
b
Sum of least squares Sampled trees
-0,568569864
2,69
11
-3,554859312
0,81
10
-4,212509914
2,22
10
-3,972315888
3,25
10
-2,389334412
2,99
10
-4,539678496
7,67
10
-4,542115395
4,01
7
-6,065471266
1,37
27
-6,027137096
18,76
63
-6,782467572
29,28
63
-6,782467572
45,55
63
Parameter estimates of the stand height curves fitted with the Michailoff – function (in alphabetical order)
Parameters
Site indices
SI - 17
SI - 19
SI - 21
SI - 23
SI - 25
C
0,07280059 0,06888142 0,06106933 0,05857689 0,05651072
dt
1,38945024 1,18520384 0,99967262 0,88578144 0,79501365
h1
12
14
16
18
20
h2
30
32
35
37
39
Hi at index age
17
19
21
23
25
Hi at rotation end
23.5
25.3
27.4
29.3
31.2
Parameter estimates and attributes of the preliminary Almendro site index curves
Parameter estimates
a
b
c
d
Los Almendros
32,8931169 1 0,05697188 1,09214275
Cope San Juan
40
1 0,03454887 0,6798233
Montealegra
40
1 0,0222607 0,63735647
O. Rodriquez
40
1 0,02914949 0,75988554
Montagnini - Thinned
40
1 0,07078486 0,96047437
Montagnini - Unthinned 32,5106876 1 0,07971772 0,84208541
Plantations
*SSR: Residual sum of squares
Used parameter values for the Chapman - Richards top height growth model
103
SSR*
1,36872872
11,3553863
8,66314029
8,4894628
4,47393735
2,29128769
APPENDICES
Appendix 5 - Photos
Picture 1: The commercial Almendro plantation “Santa Cecilla” in SGGR 1, 7.8 years
Picture 2: The COSEFORMA plot “Montealegra“, 18.4 years, SIGR 2
104
APPENDICES
Picture 3: Silvopastoral system with Almendro, “Olman González”, 14.8 years, SIGR 3
Picture 4: The oldest Almendro plantation, “Canadian Trial”, 24 years, SIGR 4
105
APPENDICES
Picture 5: Almendro in mixed plantations of RTT, “ConCol”, 8.1 years, SIGR 5
Picture 6: Mixed Almendro plantation in the highlands of Turrialba, “Mulas”, 6.6 years, SIGR 6
106
APPENDICES
Picture 7: Almendro in the ForestFinance plantation „Pampanillo”, 11.8 years, SIGR 7
Picture 8: Remnant Almendro trees on a pasture close to Sarapiqui, SIGR 4
107
EIDESSTATTLICHE ERKLÄRUNG
EIDESSTATTLICHE ERKLÄRUNG
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108