L Guinee MSc thesis

Transcription

L Guinee MSc thesis

A rapid assessment of sustainability issues using market surveys and
species distribution models
By: Lieke Guinée
5 July 2013
Major research project report
Master’s programme Environmental Biology
Utrecht University
Supervision:
Alexandra M. Towns MSc
Tinde van Andel PhD
NCB Naturalis – National Herbarium Netherlands section Leiden
Leiden University
Peter A.H.M. Bakker PhD (examiner)
Utrecht University
Context
This report presents the results of my major research project, part of the master’s programme
Environmental Biology at Utrecht University. The research project was part of a larger project led
by postdoc-researcher Tinde van Andel called Plant Use of the Motherland: Linking West African
and Afro-Caribbean Ethnobotany. I was under the direct supervision of PhD student Alexandra M.
Towns, whose sub-project is called Plants Used for Women’s Health and Childcare in Benin and
Gabon. The research team was completed by PhD student Diana Quiroz, fellow students Esther van
Vliet and Britt Boogmans, and volunteer Sofie Ruysschaert. Niels Raes (NCB Naturalis) supervised
the modelling of species distributions. Fieldwork in Gabon was conducted in cooperation with the
Herbier National du Gabon at the Institut de Pharmacopée et de Médecin Traditionnelle
(IPHAMETRA).
Funding
The larger project Plant Use of the Motherland is funded by the Netherlands Organisation for
Scientific Research (NWO-Vidi-Vernieuwingsimpuls).
This individual research project was funded by:
Alberta Mennega Foundation
Foundation Jo Kolk Studiefonds
FONA Foundation for Research on Nature Conservation
K.F. Hein Fonds Studie en Individuele Noden
Cover image: freshly harvested Annickia affinis bark in Gabon, picture by L. Guinée
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Sustainability aspects of medicinal bark, root and wood harvest in Gabon
Table of Contents
Abstract ................................................................................................................................................. 4
1.
2.
3.
4.
5.
Introduction ................................................................................................................................... 5
1.1
Study area: Gabon ................................................................................................................. 7
1.2
Rapid sustainability assessment ............................................................................................ 8
1.3
Conservation significance ...................................................................................................... 9
Materials & Methods .................................................................................................................. 10
2.1
Market surveys .................................................................................................................... 10
2.2
Plant use interviews ............................................................................................................ 11
2.3
Observation of harvest practices ........................................................................................ 11
2.4
Plant identifications ............................................................................................................. 12
2.5
Compilation of a database and a shortlist ........................................................................... 12
2.6
Species distribution modelling ............................................................................................ 14
Results ......................................................................................................................................... 15
3.1
Market surveys .................................................................................................................... 15
3.2
Plant use interviews ............................................................................................................ 17
3.3
Observations of harvest practices ....................................................................................... 18
3.4
Shortlist of commercial species with sustainability issues .................................................. 23
3.5
Species distribution models ................................................................................................ 24
Discussion .................................................................................................................................... 28
4.1
Limitations ........................................................................................................................... 29
4.2
Conclusion ........................................................................................................................... 29
References ................................................................................................................................... 32
Appendix 1. DNA analysis report......................................................................................................... 35
Appendix 2. Market survey results ...................................................................................................... 38
Appendix 3. Plant use citations ........................................................................................................... 40
Appendix 4. Plant species with sustainability scores .......................................................................... 41
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Abstract
Medicinal plants in Africa are used on a large scale and many people depend on them for
subsistence. A correspondingly large scale harvest, especially near urban centres, could have
detrimental effects on wild populations and is unlikely to be sustainable. This report presents a
rapid assessment of the sustainability of the trade and harvest of medicinal plants in Gabon, with a
focus on bark, roots and wood. Market and use surveys were performed and for each of the 55
identified species a number of factors that influence sustainability were established, such as
cultivation status, abundance and proxies for harvesting intensity. A shortlist of eight species was
further analysed by modelling their distributions and comparing these to current and future land
use in Gabon, to assess their future availability for harvest. Baillonella toxisperma, Guibourtia
tessmannii and Copaifera religiosa were found to be the species that are most likely facing
sustainability issues in Gabon, mainly due to their high medicinal value or prevalence on markets,
combined with a limited distribution (C. religiosa) and/or conflicting use as major timber species (B.
toxisperma, G. tessmannii). It is advisable to devote more research to these and other species on
the shortlist to secure their future occurrence and availability for harvest.
Keywords: Medicinal plants, bark harvest, Gabon, sustainability, species distribution modelling
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1. Introduction
Humankind has always depended upon the natural environment for food, fuel, medicine and
numerous other goods and services. In turn, since time immemorial human populations have
influenced and altered their surrounding nature and landscape. Currently, this influence can be
seen clearly in logging, deforestation for agriculture or other human activities, and even climate
change.
Perhaps less obvious but nonetheless important is the use of non-timber forest products (NTFPs).
Depending on the definition, NTFPs include all products derived from (tropical) forests, of plant or
animal origin, other than commercial timber. More general definitions also include products from
human-modified and/or semi-arid areas such as disturbed forest and farmland (Clark & Sunderland
2004; Ros-Tonen 2012). There is an immense variation in both origin and purpose of NTFPs:
bamboo and rattan for construction, leaves, roots, seeds, fruits, mushrooms and bush meat for
food or spices, oils and resins for fuel or rituals, and ornamental plants for landscape. This report
however will focus on one particular use category: medicine. NTFPs are a source for some Western
pharmaceuticals, either directly as an ingredient or indirectly as a template for chemical synthesis.
Although current data is not readily available, it has been reported that in the 1960s 25% of
prescriptions supplied from pharmacies in the USA contained ingredients of plant origin and 37% of
121 plant drugs were derived from tropical rain forests (Farnsworth & Soejarto 1991). However,
NTFPs are particularly indispensable in traditional medicine, for which it is estimated that the
majority of used species are harvested from the wild (Cunningham 1993; Schippmann, Cunningham
& Leaman 2002; Hamilton 2004).
In developing countries a large percentage of the population uses traditional medicine, for their
primary healthcare or additional to Western medication. For Africa the estimates of this percentage
vary from 80% up to even 95% (Anyinam 1995; WHO 2002). Western medicine is often unavailable,
too expensive or traditional medicine is preferred due to cultural or religious reasons. Although
animal products are sometimes used (e.g. honey), traditional medicines are mainly made of plants
or plant parts: barks, roots, leaves, fruits, seeds and exudates.
Many positive effects of the existence and use of NTFPs, including those used as medicine, have
been reported since NTFPs were first defined. They benefit local communities by providing an
(additional) income or by forming a direct source of food, medicine, construction material, etc.
Additionally, NTFPs have been shown to be important contributors to nature conservation; they
form an incentive for local communities to protect their surrounding environment, especially since
the existence of many NTFPs depends on the presence of intact ecosystems (Shanley, Luz &
Swingland 2002).
The advantages of NTFP use are particularly evident when NTFP harvest is compared to other land
uses, such as logging and agriculture. Logging, including selective logging, damages not only the
timber trees but also neighbouring trees and large parts of the understory; it alters many conditions
in the forest, such as light availability, the soil surface and drainage patterns (Laird 1999; Putz et al.
2000b; Putz, Dykstra & Heinrich 2000a; Putz et al. 2001). Additional to these direct effects are the
indirect effects of the accessibility of the forest due to the logging roads that are created
(Minnemeyer 2002).
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Figure 1.1 Generalised
biodiversity effects of a range of
forest uses plotted against
expected short-term financial
returns to forest owners or
concessionaires. NTFPs: Non
Timber Forest Products.
Enrichment planting: increasing
the stocking of commercial
species by planting seedlings or
seeds in logging gaps. Reduced
impact logging (RIL): logging that
aims to promote regeneration
and minimise damage to soil and
non-target species. The arrow
indicates the position of NTFPs.
Adapted from Putz et al. (2001)
NTFP harvest, in comparison, mainly influences the population or species in question, whereas the
forest ecosystem is influenced to a far lesser extent (Boot 1997). Figure 1.1 illustrates the financial
profitability and negative impacts on nature of NTFP use compared to other uses of forest.
Owing to the positive effects of NTFP harvest, these products have received a lot of attention
among conservation practitioners. At the same time however, many authors expressed their
concern regarding the negative impacts of NTFP harvest and consequently the sustainability 1 of
extraction (Cunningham 1993; Cunningham & Mbenkum 1993; Schippmann et al. 2002; Ticktin
2004; Ticktin & Shackleton 2011). The large scale use of medicinal plants in developing countries
and the corresponding commercial trade almost inevitably lead to sustainability issues. Schippmann
et al. (2002) estimated that 8% or 4,160 of all medicinal plant species are currently threatened with
extinction. Moreover, long before a species becomes completely extinct, it could become locally or
commercially extinct, meaning the prices of certain products no longer outweigh the costs of
harvest and transportation so they would disappear from the market. This means a medicinal plant
would no longer be available for the people who depend on its harvest, trade and use.
Whether or not a species is harvested sustainably depends on many ecological, socio-political and
economic factors, which are often interrelated (Ticktin & Shackleton 2011). One important
ecological factor is the harvested plant part, which can be leaves, fruits, seeds, exudates, bark,
roots, or woods. This research project focuses on the latter three: bark roots and wood, also known
as the woody parts of a plant. These plant parts are interesting with regard to sustainability
because when roots and wood are harvested, the individual is almost always killed due to
uprooting or felling. Likewise, the removal of bark can kill trees by interrupting downward phloem
translocation (Kramer & Kozlowski 1979). Additionally, thick bark from the main trunk of mature
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Sustainable harvest is defined in this context as a system in which the resource (medicinal plants or plant
parts) can be harvested indefinitely from a limited area of its ecosystem (e.g. forest) with negligible impact on
the structure and dynamics of the plant populations being exploited (Peters 1994).
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trees is preferred over bark from young trees or from branches (Mander 1998). This can have
consequences for population dynamics: research has shown that if harvest leads to the death of the
individual, most tree populations cannot stand even the lowest levels of harvest (Ticktin 2004).
Besides the ecological implications of their harvest, barks, roots and woods are also relatively
important on the African medicinal plant market. Cunningham (1993) mentions for example that
throughout southern Africa, herbal medicine that is dried or has a long shelf life dominates herbal
medicine markets. Besides seeds and fruits, roots and bark form a major share of these products.
Although leaf material was found to be more important in Côte d’Ivoire (Cunningham 1993), this
was not the case in Ghana, where roots (20%) and bark (18%) made up the largest part of species
diversity found on markets (Van Andel, Myren & Van Onselen 2012). This shows that the relative
importance of different plant products can differ markedly between regions and countries. In
general, however, barks and roots seem to be very important in traditional medicine in Africa, more
than in the New World (Voeks 2004).
Other ecological factors that influence sustainability are the distribution and abundance of a
species. The smaller the distribution and the rarer a species is, the less likely it is that the harvest is
sustainable (Peters 1994; Ticktin & Shackleton 2011). However, a species which is abundant and
widespread may still face sustainability issues if the harvest rate or intensity is very high. At the
same time, the pressure on a rare species with a narrow distribution can be considerably lifted
when it is cultivated instead of harvested from the wild. In addition to the factors that depend on
the harvest and trade of a plant species for medicinal purposes, many species may also be
threatened by other, conflicting uses of both the species and the land it grows on (Van Dijk &
Wiersum 2001; Shanley et al. 2002; Ticktin & Shackleton 2011). Medicinal tree species are often
logged for timber locally or on a large international scale. Additionally, tree species can be used for
their edible fruits, seeds or for fuel wood.
1.1 Study area: Gabon
Many of the previously mentioned factors
differ per region or country. This research was
conducted in Gabon, a sparsely populated
country in Central Africa. It is slightly smaller
than Italy and has just over 1.6 million
inhabitants, of which 86% live in urban areas
(CIA 2012). Due to the low population density,
political stability and especially its large oil and
mineral reserves, Gabon has become one of
the wealthier countries in Africa. As a result of
this, Gabon has been spared the large
deforestations that neighbouring countries
have suffered from, leaving an estimated
forest cover of 60 to 85% (FAO 2011). Gabon
therefore harbours the largest remaining part
of the Guineo-Congolese forest ecosystem,
known for its high species diversity and Figure 1.2 Map of Gabon. Source:
endemism (Collomb et al. 2000). This offers a http://mapsof.net/map/topographic-map-of-gabon-en
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unique possibility to study medicinal plant use and its sustainability in an environment that is
relatively undisturbed by humans.
At the same time however, there are some large urbanized areas such as the capital city Libreville
where natural resource pressure (including medicinal plant use) on the surrounding forests could
be high, resulting in sustainability problems. Since the country’s oil and mineral reserves are
diminishing, the Gabonese government is increasingly dependent on timber production and export
(Laurance et al. 2006). Together with the growing population this intensifies the pressure on the
remaining forest. In the near future Gabon could fall victim to large scale deforestations, like many
other African countries have already done in the past. In fact, Gabon currently has the highest rate
of loss of primary forest in Africa: 330,000 ha/year (FAO 2011), equivalent to almost a tenth of the
surface area of the Netherlands. Mining and logging concessions already cover vast areas, with over
half of Gabon’s forests allocated to logging concessions in 2000 (Collomb et al. 2000). Moreover,
although there are laws obliging timber companies to protect and manage their forests sustainably,
these laws are applied nor enforced well, additional to frequent encroachment of community lands
and protected areas by illegal logging practices (Collomb et al. 2000; Wily 2012).
1.2 Rapid sustainability assessment
If one wants to assess the true sustainability of harvest of a certain plant species, it is necessary to
perform yield studies, regeneration surveys, matrix model projections, etc., which can result in a
harvest limit. However, this is rather laborious and time-consuming, even for one species.
Moreover, Ticktin and Schackleton (2011) have stressed that harvest limits vary to such an extent
over space and time that they are of little use outside the location and conditions where they were
determined. Instead of analysing the specific sustainability of one species, the aim of this research
project was to acquire a more general picture of possible sustainability issues of the harvest of
medicinal bark, roots and wood in Gabon. This was attempted by performing a rapid assessment
which consisted of an extensive market, use and harvest practice survey, which lead to the
compilation of a shortlist of species with sustainability issues. From this shortlist, species
distribution models were created which give a prediction of the future availability of these species
Gabon, by comparing the fraction of the modelled distributions that fall within protected areas and
logging concessions. In order to shortlist the commercial species with conservation problems, the
following research questions were posed:
1. Which species of barks, roots or woods are traded for medicinal or ritual purposes?
2. Can the extraction of these species be considered sustainable?
a. Which plant part is used or traded?
b. Are the species harvested from the wild or cultivated?
c. From which vegetation types are the plants or plant parts harvested?
d. What is the harvesting intensity?
e. Are the species (locally) rare or abundant?
f. Are the species also used for purposes other than medicinal or ritual (e.g. for timber)?
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1.3 Conservation significance
This research project has the potential to contribute to the conservation of Gabonese nature in
multiple ways. The primary aim was to identify plant species that are possibly not being harvested
sustainably and thus are at risk of (local) extinction. This can lead to follow-up research on these
species in which ecological effects of harvest can be studied and quantified, or harvest limits can be
determined. Additionally, the local population can potentially be motivated to contribute to
conservation of nature, if it becomes clear that medicinally important plant species are threatened.
A much used argument for conservation of tropical rainforest is also that due to its high diversity,
many miracle medicinal plants are still waiting to be discovered. Gabon may harbour even more of
these medicinal species than its neighbouring countries because of its high forest cover. This survey
of traditional medicinal plant use, in combination with a list of species that currently face
sustainability issues, can contribute to the arguments favouring the conservation of the Gabonese
nature.
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2. Materials & Methods
The fieldwork of this research project was carried out in Gabon (4°S-2°N, 8-14°E) between July and
September 2012, which falls into Gabon’s long dry season of May until September. Additional
fieldwork, which added to the data in this report, was completed by the two PhD students of the
larger project Plant Use of the Motherland: Linking West African and Afro-Caribbean Ethnobotany
between June and November 2012. September until November is known as the short rainy season.
The average annual rainfall of Gabon is 1,831 mm. The country has a narrow coastal plain, a hilly
interior covered mostly by wet, lowland rainforest and some savannah areas in the east and south
(CIA 2012).
This research project consisted of several components which together resulted in a rapid
assessment of sustainability issues of medicinal bark, root and word harvest in Gabon. Market
surveys and plant use interviews were conducted to identify which species were traded and used,
but also to obtain indicators for harvest intensity. Additionally, medicinal plant harvesters were
interviewed and accompanied into the field to observe harvest practices and thus to obtain
information regarding possible sustainability issues. For each species, the previously described
information was combined with data from various web databases in order to establish a number of
sustainability factors. Based on these factors, a shortlist was created of species which are the most
likely to face sustainability problems. These species were further analysed using species distribution
models in order to assess their distribution and future availability within Gabon.
The research in Gabon was conducted in cooperation with the Institut de Pharmacopeé et de
Medicine Traditionelles (IPHAMETRA) and the Agence Nationale des Parcs Nationaux (ANPN). All
the research was conducted according to the Code of Ethics of the International Society of
Ethnobiology.
2.1 Market surveys
Market surveys were conducted in order to list the species that are traded. Additionally,
information collected from these surveys was used to calculate the quantity in which species were
offered for sale on the markets, which can be used as a proxy for harvest intensity. Market surveys
were carried out in the capital city of Libreville, Port-Gentil, Oyem and Lambarene. In Libreville, two
markets were found to sell solely medicinal and ritual products. The first, La Peyrie, was rather
isolated and located on a side street (0°24’10”N, 9°27’18”E). The second was located close to the
major market area Marché Mont Bouet (0°24’08”N, 9°27’19”E). Besides the medicinal markets, a
survey was also taken of Nkembo market (0°25’04”N, 9°27’17”E), a market dedicated mainly to
foodstuffs and clothes. In Port-Gentil, one stall was surveyed (Marché Bornave, 0°43’04”S,
8°46’10”E). In Oyem, two markets (Ngouema and Akouokam, 1⁰34’37”N, 11⁰34’14”E) were
surveyed, of which only one stall was specialised in traditional medicine, mainly barks. In
Lambaréné one stall was surveyed (Marché Isaac, unknown coordinates). Per market, one to eight
stalls were surveyed, with a total of 23 stalls.
The surveys consisted of counting and weighing each product. The market vendor was asked the
vernacular name, use and the price (in XAF, Central African CFA franc2; a high price can be an
2
At the time of research (July 2012), the exchange rates were 656 XAF per 1 EUR and 518 XAF per 1 USD
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indicator for scarcity) of the sales unit of each product, in addition to the vendor’s name, ethnicity,
earnings and volume sold and discarded per week. Plant products that were unknown were
purchased and taken home to process into herbarium vouchers and identify to species level. For
this report, only the data on barks, roots and woods were used in the further analyses.
For each identified species, the percentage of stalls that sold the product was calculated and the
total weight offered for sale per day across the 23 surveyed stalls was calculated based on the
average weight of a sales unit and the total count of sales units. Consequently, these numbers are
an underestimation of the total amounts offered for sale on the markets, but they serve the
purpose of determining relative importance compared to other species. A detailed explanation of
the methods used in the market surveys can be found in Towns et al. (forthcoming).
2.2 Plant use interviews
Another proxy for harvesting intensity was determined by using data from ethnobotanical
questionnaires conducted by A.M. Towns and E. van Vliet. 53 informants were interviewed about
plants used for women’s health and childcare (Van Vliet 2013, Towns forthcoming). The informants
were almost exclusively women and included traditional healers, market women, plant collectors
and midwives. Semi-structured questionnaires were used to obtain information on which plants
were used, the specific plant part used, preparation and administration recipes. Based on the
results of these questionnaires it was calculated how often each species was cited by all informants.
This number was used as an indicator for harvesting intensity.
2.3 Observation of harvest practices
Ten commercial and non-commercial harvesters were accompanied into the field in order to (1)
match earlier acquired market samples with trees in the field to facilitate identification, and (2)
observe harvesting practices. The actual harvest techniques that were used provided important
information with regard to the potential sustainability of medicinal plant harvest. In the Libreville
area the accompanied harvesters included one harvester specialised in barks, one traditional healer
and eight market women who were generally more specialised in herbs, but occasionally also
harvested bark or roots. Additionally, one more harvester specialised in barks was interviewed
when it proved to be impossible to make arrangements to accompany him into the field.
For each harvested tree, vernacular names, uses, and percentage of circumference harvested were
recorded, in addition to harvesting techniques and practices. Bark samples and if possible leaf,
flower or fruit samples were collected in addition to GPS coordinates. Furthermore, some general
questions with regard to harvesting practices and habits were asked. Freelisting exercises were
performed to obtain names of species that were getting rare in the experience of harvesters, and to
obtain names of species that they sold or harvested most often.
In the north of the country, in the province of Woleu-Ntem, we visited Oyem and the villages Akam
Essatouk (1⁰48’51”N, 11⁰26’18”E) and Ebomane (2⁰10’14”N, 12⁰03’09”E). In Oyem we found only
one medicinal plant stall on the market, so no large-scale trade seemed to be taking place. In the
villages, given that no commercial harvesting was taking place, I was assisted by knowledgeable
elders to match unidentified bark samples from the Libreville and Oyem markets. During these trips
into the area surrounding the villages, signs of previous bark harvest by locals were observed.
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2.4 Plant identifications
Of every collected specimen, a duplicate was deposited in the Herbarium of Gabon (LBV) and in the
National Herbarium Netherlands, section Wageningen (WAG), now part of NCB Naturalis.
Identifications were partly done in Libreville but always confirmed in Wageningen and in the
Naturalis wood collection in Leiden. Some collections lacked fertile parts or even leaves, as was
often the case with market samples. For these collections literature such as Les Plantes Utiles du
Gabon by Raponda-Walker and Sillans (1961) was used as a reference to compare vernacular
names. Especially in the case of Fang and Mpunu names many samples could be identified
accurately up to species level by means of this book. Collections that remained unidentified were
shown to a wood anatomist, and one collection was analysed by DNA analysis (see appendix 1 for
detailed methods). Family, scientific and author names were checked for accuracy with The Plant
List (“The Plant List” 2010, http://www.theplantlist.org, accessed on February 1st 2013).
2.5 Compilation of a database and a shortlist
A database was compiled containing the scientific and vernacular name, collection numbers and
uses of each species. Additionally, a number of sustainability factors were determined for each
species as specified below:
a. Harvesting intensity:
To determine harvesting intensity, two main indicators were used: total market weight
offered for sale across the 23 surveyed stalls and the number of citations in plant-use
interviews of Van Vliet and Towns. For some species we were also able to observe how
much material (mainly bark) was harvested per individual.
b. Abundance in the wild:
The abundance or rarity of a species was based on personal observations in the field, the
opinion of harvesters, and literature such as the PROTA web database (Plant Resources of
Tropical Africa, http://www.prota4u.org/), the IUCN Red List of Threatened Species and
the CITES species database (http://www.cites.org).
c. Cultivation status:
Cultivation status was determined for each species by means of observation in the field or
literature (e.g. the PROTA web database). Although there are many gradations of
cultivation, for practical reasons we decided to use the two categories wild, and
cultivated, where wild means the product is harvested from individuals which grow in the
wild, independent of human interference; and cultivated means the plant is grown in a
garden, backyard or cultivated field, regardless of whether it was sown or brought in from
the wild as a grown plant.
d. Vegetation type:
The vegetation type of a species was determined on the basis of both available literature,
databases (e.g. PROTA database) and our own observations in the field. See table 2.1 for
vegetation classifications that were used.
e. Other uses:
Literature such as the PROTA database and our own market surveys were used to assess
whether each species also had other uses besides their use as medicine, such as timber or
edible fruits.
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Based on the sustainability factors, a shortlist of priority species was compiled. This approach is
similar to what was done by Wilkie (1999) for NTFPs in Central Africa, albeit that different criteria
for selection were used. Another difference is that the sustainability factors were converted to a
score on a scale from 1 to 5, with 1 meaning little negative impact or a positive impact on
sustainability and 5 meaning highly negative impact on sustainability. Species were scored
relatively, i.e. compared to the range of values or categories that were present in all the assessed
species. When information on a certain factor was unavailable for a species it was given a score 3.
In case of the “total weight” and “citations” score, the boundaries for scoring were set by
calculating the 20th, 40th, 60th and 80th percentile of the total range of values so that the species
would be somewhat evenly distributed among the scores.
The “plant part” factor was scored 5 if it concerned wood or roots, since for the harvest of these
plant parts, the entire plant is generally uprooted or felled. Bark harvest was scored 4 because
usually trees can survive bark harvest (unless a tree is ringbarked), but the damage can be
extensive. Resin harvest is viewed as the least damaging and thus scored 3. The “abundance/rarity”
score was based on a combination of information from harvesters, the IUCN Red List status and the
PROTA web database, the details of which can be seen in table 2.1.
Table 2.1 An overview of the sustainability factors, scores and categories. Abbreviations: IUCN: IUCN Red List status;
NE: not evaluated; LC: least concern; NT: lower risk/near threatened; VU: vulnerable; H: commercial harvester; NA: not
available (IUCN 2012)
Score
Factor
Plant part
Harvest intensity: total
weight offered for sale
across surveyed stalls
Harvest intensity:
citations
Abundance/rarity
1
2
3
4
5
0-0.32 kg
0.33-0.69 kg
Resin
0.70-1.64 kg
Bark
1.65-9.67 kg
Wood, root
9.68-138.69 kg
0 citations
-
1-2 citations
3-6 citations
7-30 citations
PROTA:
common;
IUCN: LC, NE
Private yard
PROTA:
widespread but
not common;
IUCN: LC, NE; all
cat. NA
Savanna; NA
H: getting rare &
IUCN: LC; PROTA:
scattered & IUCN: NT
Vegetation type
H: getting rare;
PROTA:
scattered/rare/
uncommon/NA;
IUCN: NE, VU, NT
Primary forest
Cultivation status
Cultivated
Other uses
-
PROTA: locally
dominant/
abundant,
widespread; IUCN:
LC, NE
Secondary forest
and -shrubland;
Wild but frequently
cultivated
-
No major other
use or NA
Primary and
secondary forest
Wild but occasionally
cultivated
Timber (small scale);
dye; edible
fruits/seeds; fibre;
fuel
Only harvested
from the wild
Timber (large scale,
export)
The “other uses” factor was scored 5 only if the species was a major timber species, mentioned
either in the list of Major Tropical Logs Species Exported by Gabon (ITTO 2011a) or as a species that
is harvested in increasingly large volumes in Status of tropical forest management 2011: Gabon
(ITTO 2011b). Species with an average priority score of higher than 4 were included in the shortlist
and in the further analysis using species distribution modelling.
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2.6 Species distribution modelling
Based on the sustainability factors and their scores defined in the previous paragraph, I compiled a
shortlist of eight species which are likely not being harvested and traded sustainably. To further
analyse the sustainability status of these species we made a species distribution model (SDM) for
each of them.
The SDMs were created using Maxent software (version 3.3.3k, http://www.cs.princeton.edu/
~schapire/maxent/) (Phillips, Anderson & Schapire 2006). Maxent uses the “maximum entropy
method” to estimate the distribution of a species in a certain area based on collection localities
(presence records) and environmental predictor variables. As presence records the occurrences of
the eight shortlist species were selected from the BRAHMS database of collections of the National
Herbarium of the Netherlands, part of NCB Naturalis. Maxent was set to “remove duplicate
presence records” which resulted in 14-49 unique presence records per species.
As environmental variables 19 bioclimatic variables of current conditions were obtained from the
WorldClim dataset (http://www.worldclim.org). The variables were standardised and analysed
using Pearson’s correlation and principal component analysis (PCA) in order to select only the
variables that were not correlated (r>-0.7 or r<0.7) to another variable. All data layers were scaled
to a 5 arc-minute (0.08333°, approx. 9.28x9.28 km) resolution. To prevent overfitting of the models,
the extent of the environmental layers and the resulting SDMs was limited to the wetter types of
lowland rainforest of White’s vegetation classes (1983), east of the Dahomey Gap, and a buffer of 1
degree around the presence records. This resulted in an extent of 52752 (314x168) grid cells with a
lower left corner at 6.667S, 4E.
The applied threshold rule was the “10 percentile training presence”. All SDMs were tested for
significant difference from what is expected by chance by using the null-model methodology for
presence-only data as it was introduced by Raes and ter Steege (2007). The AUC (area under the
curve) values of the ROC (receiver operating characteristic) plots of the SDMs were compared to
the upper limits of one-sided 95% confidence intervals of AUC values. These were based on
frequency histograms of 99 AUC values generated by randomly drawing a number of collection
localities (equal to the number of collection locations of each species) from the previously
mentioned geographical extent.
GIS data of Central African countries, land cover, Gabonese National Parks, logging concessions,
populated places, roads and railroads were taken from the Interactive Forestry Atlas of Gabon
provided by the World Resources Institute (http://www.wri.org/publication/interactive-forestryatlas-gabon, Makak & Mertens 2009). The polygon of the country Gabon was converted to a raster
of the same resolution and extent as the SDMs to calculate the percentage of each SDM that fell
within Gabon using R Studio (ver. 0.79, http://www.rstudio.com/) and Microsoft Excel. Within the
extent of Gabon, polygons of National Parks and logging concessions were also converted to rasters
in order to calculate the percentages of SDMs within Gabon that fell within protected areas or
concessions. These percentages are important indicators for (future) availability of medicinal plant
species for extraction, since the local population is not allowed to harvest from protected areas and
many species are extracted for timber (making them unavailable for harvest as medicine) in logging
concessions.
All maps were created using ArcGIS (ver. 10.0) and the projected coordinate system WGS 84.
14
3. Results
3.1 Market surveys
4%
23%
34%
Woody parts: bark,
roots, wood
Reproductive parts:
fruits, seeds, flowers
Leaves
Figure 3.1 Type of plant part sold on the
market as a percentage of the total number
of species surveyed (n=176)
Entire herb
16%
23%
Other (e.g. resin)
A summary of the overall results of the market surveys is shown in figure 3.1. The figure shows the
percentage of species of which a certain plant part was sold. Fresh plant parts (leaves and entire
herbs) together form the largest share (39%), but bark, roots and wood are a close second with
34%. The detailed results of only the bark, roots and wood are summarised in table 3.1 on the
following page. This table contains the results for the ten species (out of 55) with the highest total
weight offered for sale across all surveyed stalls. One product is included in this table, even though
the plant part concerned is not woody: the resin of Aucoumea klaineana. The latter is the main
constituent (together with the bark of Xylopia aethiopica) of the torche indigène, a commonly sold
torch used in many ceremonies. Because of its importance and prevalence on the markets, this use
of A. klaineana was also included in the sustainability analysis. The results of the remaining plant
parts (e.g. leaves, herbs, fruits) will be published by Towns (forthcoming). A product that was also
sold frequently and in large quantities (33.0 kg total weight) is the ready-made bottle. These bottles
contain woodchips and pieces of bark and roots and are meant to be used for a specific disease or
as aphrodisiac. Since their content is so varied and difficult to identify, this product was not
incorporated in the further analyses.
Figure 3.2 A shop in the
outskirts of Libreville selling
vegetables, firewood and
indigenous torches
(indicated by the green
arrow) composed of A.
klaineana resin and X.
aethiopica bark. Picture by
L. Guinée
15
Table 3.1 The ten species out of 55 encountered during the 23 market surveys with the highest total weight
offered for sale over all surveyed stalls. The total weight is the average weight of a sales unit (not shown)
multiplied by the total number of sales units counted in the surveyed stalls. Note that this amount is not
extrapolated over the entire market so it is an underestimation of the overall weight offered for sale.
Coll.
Number
Family
Species
Local Name
Plant
part
Growth
form
AMT750,
AMT1016,
AMT 939,
AMT 1050
AMT 743
BURS
Aucoumea klaineana
Pierre
bark,
resin,
wood
ANNO
Annickia affinis (Exell)
Versteegh & Sosef
AMT 755
FABA
Copaifera religiosa
J.Leonard
okoumé
(common, Punu,
Fang), torche
indigène (French)
bois jaune
(French), mfo
(Fang)
mutombi
(Masango)
AMT 757,
AMT 1029
FABA
Daniellia klainei A.Chev.
AMT 786
CLUS
Garcinia lucida Vesque
AMT 750
ANNO
AMT 756,
DQ 961
AMT1010,
DQ 959
FABA
Xylopia aethiopica
(Dunal) A.Rich.
Distemonanthus
benthamianus Baill.
Erythrophleum ivorense
A.Chev.
AMT 941,
1032
EUPH
AMT 777
CLUS
FABA
Croton oligandrus
Pierre ex. Hutch., C.
mayumbensis J.Léonard
Garcinia kola Heckel
Total
weight
(kg)
138.69
% of
stalls
tree
No.
sales
units
218
bark
tree
156
25.94
35
bark
tree
88
21.69
22
pangu,
mutanghani
(Masongo)
esok, esop (Fang)
bark
tree
61
13.69
13
bark
tree
130
13.56
9
torche indigène
(French)
movengi
(Masongo)
mbaka (Punu),
bois de lune
(French)
ongen (Fang)
bark
tree
204
12.83
35
bark
tree
71
11.22
17
bark
tree
46
11.13
17
bark
tree
60
10.71
13
onyeng (Fang)
bark
tree
65
10.31
13
39
The results shown in table 3.1 are ranked based on the total weight across all surveyed stalls, thus
offering an insight into which species were offered for sale in the largest quantities. The resin of A.
klaineana used in indigenous torches is at the top of the list, followed by Annickia affinis, which is
less than one fifth of the weight. The indigenous torches were a very common product on medicinal
markets, and were even observed being sold in a shop selling mainly vegetables and firewood (fig
3.1). Indigenous torches are an important part of ceremonies of Bwiti, one of Gabon’s three official
religions, which combines animism, ancestor worship and Christianity (Fernandez 1982). Species in
the top five of total weight include Annickia affinis, Copaifera religiosa and Daniellia klainei. The
tenth species sold in large quantities was Garcinia kola. Interestingly, this bark was surveyed at two
stalls in Oyem, in Lambaréné and in Franceville, but was not sold at the medicinal markets in
Libreville. The stalls in Oyem, Lambaréné and Franceville sold large quantities of the “bitter bark”
which is used as an additive to palm- and sugarcane wine. Upon inquiry about the absence of this
bark at the specialised medicinal markets in Libreville we were told that this particular bark is sold
at different markets, e.g. at PK53. This could be a sign that this bark is used more commonly than
other (medicinal) barks. The full list of species encountered during the market surveys can be found
in Appendix 2.
3
PK5 (pronounced “peh kah cinq”) refers to a point located along the national route N1, at five km distance
from the start of this road in the city centre.
16
Some species that were sold frequently (i.e. in a large percentage of stalls), do not show up in table
3.1 because they either had a small weight per sales unit or were not sold in large amounts per
stall. The former seems to be the case for species such as Pterocarpus soyauxii (sold at 35% of the
stalls), which is sold in powdered form known as “kaolin rouge” and used as a colorant;
Tabernanthe iboga (26%), of which the root bark is ground and sold in small bottles (250 or 200 ml),
a very valuable and important hallucinogenic in Bwiti rituals; Anisophyllea sp. (22%) and Dorstenia
psilurus (22%), both roots, the latter being particularly small in size; and Harungana
madagascariensis (22%), which is a rather thin bark, sold in large, curled up strips. Guibourtia
tessmannii was also sold frequently (22% of stalls) but not in large numbers per stall.
Interestingly, species did not differ markedly in price on the markets that were surveyed. In
Libreville, pieces of bark had a fixed price of 500 or 1000 XAF (equivalent to €0.76 and €1.52)
depending on their size, seemingly unrelated to scarcity. This was confirmed by one of the
harvesters, who said he did not receive higher prices for barks that were more difficult to find. An
exception was Tabernanthe iboga, which was mainly sold in grinded form in small glass bottles of
100 ml (5000 XAF ≈ €7.62) or 250 ml (10,000 XAF ≈ €15.24). In Oyem, barks and roots were several
times more expensive than in Libreville, which could be due to the monopoly of the single
medicinal market stall. In Libreville, processed medicine, sold in large bottles containing wood chips
of multiple species, was also more expensive than unprocessed barks or roots. This is probably
because more labour is needed to produce processed medicine, and because the knowledge that is
needed to compound the recipe is also valuable.
3.2 Plant use interviews
Table 3.2 Ten plant species for which the use of bark, roots or wood was cited most often in interviews about medicinal
plant use for women’s health and childcare conducted by Towns and van Vliet. “Patique jaune”: disease with yellow
eyes as the main symptom; “fesse rouge”: a culturally bound disease (CBD) similar to diaper rash; “la rata”: a CBD
characterized by green faeces and a firm and painful belly on the left side (Van Vliet 2013).
Species
Use
Count
Pterocarpus soyauxii Taub.
Measles, chicken pox, diarrhoea, anaemia, increase breast milk
production
30
Malaria, “patique jaune”, STD’s, anaemia, hypertension
25
Annickia affinis (Exell) Versteegh &
Sosef
Harungana madagascariensis Lam. ex
Poir.
Alstonia congensis Engl., A. boonei De
Wild.
Circumcision healing, diarrhoea, “fesse rouge”, measles,
respiratory problems, menstruation pain, post-partum infections
Malaria, intestinal worms, asthma, “la rata”, increase breast milk
production
22
18
Pentaclethra macrophylla Benth.
Colic, intestinal washing, vaginal cleanse, facilitate delivery
15
Antrocaryon klaineanum Pierre
Womb cleanse after delivery, female infertility, backache,
anaemia, vaginal tightening
13
Cylicodiscus gabunensis Harms
Intestinal worms, malaria, diarrhoea
12
Guibourtia tessmannii (Harms)
J.Leonard
Against sorcery, newborn bath, hypertension
10
Pycnanthus angolensis (Welw.) Warb.
Fontanels, anaemia, cough, “fesse rouge”
10
Baillonella toxisperma Pierre
Womb cleanse after delivery, post-partum infections, vaginal
cleanse, circumcision healing
10
17
The top ten barks, roots and woods from the interviews of Towns and Van Vliet (table 3.2)
correspond largely to the ones most frequently offered for sale at the markets (table 3.1). Their
relative importance, however, shows differences, as is apparent in the case of Alstonia boonei/ A.
congensis (used interchangeably), which was the fourth most cited product but only the 36th most
sold on markets. Antrocaryon klaineanum is a species which figures quite high on the list of most
cited (6th) but was not found during the quantitative market surveys, although we purchased this
bark on the market once. See appendix 3 for a full list of used species and the number of citations.
3.3 Observations of harvest practices
Figure 3.7 on page 20 shows the locations of the fieldwork that was conducted near Libreville and
in the rural areas around Oyem. We observed major differences between the practices in and
around Libreville and in the northern rural areas. In Libreville, the demand for medicinal bark was
so great that there were several harvesters who were able to make a living out of harvesting and
selling solely bark. Two of these harvesters had their own stall on the Mont Bouet market, but they
also sold their barks to other market sellers so they could be considered to be wholesalers. One of
them reported to have a frequent customer who bought his barks to resell them via a website.
Overall, we observed that the herbal markets had short market chains, without many middlemen.
From what we observed, the specialised bark harvesters of Libreville typically rented a car for
harvest trips, which were usually on Monday (although they sometimes lasted multiple days). On
such a trip, large quantities of bark were harvested in order to regain the cost of the car rental. One
of the harvesters collected barks both close to the roads and further into forested areas. Another
harvester reported that he mainly harvests close to roads so he does not have to carry the barks a
long distance.
We observed several techniques for the removal of bark. They always included use of a machete,
both to cut the bark and as a lever to separate the bark from the sapwood. To obtain bark from
high parts of the trunk, harvesters used a combination of pulling (Figure 3.6), tearing, and pushing
with a pole (usually a juvenile tree was felled for this purpose)(Figure 3.5). The result of the use of
these techniques was the removal of strips of bark up to as high as 6 m from the ground (Figure
3.4). A juvenile tree was also used as a ladder to reach higher parts of the tree (Figure 3.3).
In general, harvesters seemed to be aware of the fact that a tree does not survive if it is ringbarked.
They typically left at least 10% of the circumference of the tree intact. For a number of trees from
which we witnessed bark being harvested, the average percentage of the circumference of the
trunk that was harvested was 58.8% (SD=22.6%, N=8). The height up to which harvesters removed
bark was on average 4.4 m (SD=1.7 m, N=6).
One exception to this rule was an Annickia affinis tree of which a harvester and his assistant
(supposedly accidentally) removed too much bark for it to be able to recover, and subsequently
they decided to cut down the entire tree (Figure 3.9).
18
Figure 3.6 A harvester performing the "pull-technique" for
the removal of Cylicodiscus gabunensis bark. Scarring caused
by previous harvest is visible to the left of the harvester.
Picture by L. Guinée
Figure 3.5 A harvester performing the "pole-technique" to
obtain bark from Drypetes gossweileri. At the bottom-right
scarring caused by previous harvest is visible. Picture by L.
Guinée
Figure 3.4 The result of using the pole-technique: the Figure 3.3 A fourth technique to reach higher parts of the
removal of strips of bark up to ±6 m height (the tree is the trunk: using an improvised ladder. Species unknown,
same as the previous picture). Picture by L. Guinée
possibly Erythrophleum ivorense. Picture by D. Quiroz
19
Figure 3.7 Map approximately showing
observed harvest locations near Libreville (plant
parts harvested there were transported to the
medicinal markets of Libreville) and the
fieldwork locations in rural areas near Oyem.
20
After removing the bark, most commercial harvesters and traditional healers performed a ritual
called “fermer la porte” in French or “closing the door” in English (Figure 3.8). This entails the
coverage (to different extents) of the wound (caused by the removal of bark) with some dirt.
Harvesters believe this aids the tree in the healing process. One harvester explained the ritual as
follows: “I use the bark of this tree to heal people, so I should help the tree heal as well”. Some
harvesters admit to praying and making small offerings before or after harvesting bark. This is
related to traditional religion, since it is meant to please the forest spirits. One traditional healer
also mentioned a healer cannot heal during the dry season, because the spirits of the forest have
disappeared. A limitation that holds true for all harvesters (and seems to be respected by most) is
that some forest areas are designated sacred. These sacred forests can only be accessed by
initiated (Bwiti) people or under guidance of an initiated person. However, the two most important
bark harvesters of Mont Bouet could access these forests because one was initiated and the other
said he could enter these sacred forests too, since he was “a traditional healer by birth”.
Interestingly, the latter also said there were some forests he was really not allowed to harvest
from: national parks and private forests. He also mentioned you need permits to harvest from
certain trees, such as G. tessmannii and C. religiosa. Thus far we have been unable to identify which
permit he was referring to, although we know it costs 200,000 CFA per year and it allows you to
harvest 1000 kg per trip.
Besides the claim that some traditional healers cannot harvest during the dry season, most
harvesters said they can harvest barks year-round, as opposed to certain fruits. One harvester
explained to us that he works according to a certain temporal and spatial rotation system of harvest
areas. He harvests bark from an area for a while until there are no more suitable trees. Then he
Figure 3.9 Commercial bark harvesters are removing
bark from Annickia affinis after having felled the
tree. This was an exceptional event, because usually
trees were left standing with at least 10% of the
circumference of their trunk still covered with bark.
Picture by L. Guinée
Figure 3.8 Two examples of the practice of "closing the
door": covering the wound with some dirt after harvesting
the bark. In the left case this is nothing more than a couple
hands full of dirt thrown against the trunk, in the right case
the dirt was smeared over the entire surface. Picture by L.
Guinée
21
Species harvested most often
Species getting rare
Annickia affinisa,b
Annickia affinisa
Antrocaryon klaineanumd
Bobgunnia fistuloidesb
Aucoumea klaineanac
Copaifera religiosaa,b
Copaifera religiosa
Cylicodiscus gabunensisa
a,b
Table 3.3 Species mentioned as getting rare and
species harvested or sold the most. Informants: a, b, c
different commercial harvesters, d traditional healer.
Yellow shading indicates a species is both harvested
most often and mentioned as getting rare.
Drypetes gossweileria,b
Croton sp.a
a,b
Cylicodiscus gabunensis
Guibourtia tessmanniib
Distemonanthus benthamianusc
Drypetes gossweileria
Guibourtia tessmanniia,b
Musanga cecropioidesc
Pterocarpus soyauxiic
Tabernanthe ibogad
goes to a different area to let the trees in the previous area rest and heal. He claimed most trees
can heal from debarking within two months, but he usually only returned to an area after five
years. However, during one of our trips to a certain area he mentioned it was two years since he
had last been there. On the trees he harvested from we could indeed see scarring from previous
bark removal, which he claimed was done by himself (see Figure 3.6 and Figure 3.5).
Table 3.3 shows the results of a freelisting exercise performed with two commercial harvesters, one
market saleswoman and a traditional healer. They were all asked to mention the species which they
harvested or sold the most often. The commercial harvesters were also asked to mention species
which are getting rare or more difficult to find. One harvester mentioned that these species used to
grow close to Libreville, but nowadays one has to travel at least 80 km to find them. Five out of the
six species that were getting rare were also species that were harvested the most often (see
coloured shading).
Rural areas
In rural areas of the northern province WoleuNtem, we observed harvest practices that were
very different from what we saw in urban areas.
Outside urban centres no trade in medicinal
plants seemed to be taking place. A common
sight in and around villages were trees such as
the one in figure 3.10, showing signs of repeated
harvest of small pieces of bark (see figure 3.7,
page 20 for the locations). This indicates that
rural residents only harvested bark when they
needed it, in small quantities and usually directly
by the person who was treating a disease (such
as a traditional healer or a knowledgeable elder).
We also found this to be the typical practice of
N’gangas (traditional healers) and some women
operating in urban areas.
Figure 3.10 Cylicodiscus gabunensis tree near the
village Akam Essatouk showing signs of repeated
previous harvest and scar tissue formation. Picture by
L. Guinée
22
The heart of the tree
One informant, a respected elderly woman from the village of Ebomane, explained to us that when
you harvest bark, you ‘touch the heart of the tree’ and make it bleed. That is why, when bark is
harvested too often, the tree will eventually die. In that case you have to find another tree to
harvest from. This shows that rural residents are (at least partly) aware of the impact bark
extraction can have and that they know it can be a finite, unsustainable practice.
3.4 Shortlist of commercial species with sustainability issues
None of the bark, root or wood species we encountered were listed on the CITES appendices
(http://www.cites.org).
Table 3.4 shows the eight species which had an average sustainability score of higher than four. A
full list of species and their scores can be found in Appendix 4. All of the species in the shortlist
were harvested from the wild and most of them were commercial (export) timber species (other
uses). Additionally, their harvest intensity is likely to be high as is indicated by either a large total
market weight (A. klaineana, C. religiosa, D. gossweilerii), a large number of use citations (B.
toxisperma, G. tessmannii, C. gabunensis, P. soyauxii) or both (A. affinis).
Table 3.4 Shortlist of species with high scores (average >4), divided over the various sustainability factors. The higher
the score, the more likely the species has sustainability issues.
Fam.
Species
SAPO
Baillonella toxisperma
FABA
Plant
Part
Harvest intensity
Rarity
Veg.
Type
Dom. / Other
cult.
uses
Total
Average
Market
weight
Use
citations
4
4
5
5
5
5
5
33
4.7
Guibourtia tessmannii
4
4
5
5
5
5
5
33
4.7
FABA
4
4
5
5
4
5
5
32
4.6
FABA
Pterocarpus soyauxii
5
4
5
4
4
5
5
32
4.6
ANNO Annickia affinis
4
5
5
5
2
5
4
30
4.3
BURS
Aucoumea klaineana
5
5
4
4
2
5
5
30
4.3
FABA
Copaifera religiosa
4
5
1
5
5
5
4
29
4.1
PUTR
Drypetes gossweileri
4
5
3
5
4
5
3
29
4.1
23
3.5 Species distribution models
After Pearson’s correlation and PCA analysis, six WorldClim variables were selected as
environmental predictor variables: BIO1 (annual mean temperature), BIO7 (temperature annual
range), BIO12 (annual precipitation), BIO15 (precipitation seasonality), BIO18 (precipitation of
warmest quarter) and BIO19 (precipitation of coldest quarter).
Table 3.5 shows that for all eight species, sufficient numbers of presence records were available: 14
(D. gossweileri) up to 49 (A. affinis). In the same table it can also be seen that all SDMs were
significantly better than random chance.
Species
Training
AUC
value
0.925*
Null AUC
value
Annickia affinis
No.
training
samples
49
Aucoumea klaineana
40
0.972*
0.742
26
0.936*
0.780
Copaifera religiosa
17
0.986*
0.828
30
0.966*
0.768
14
0.776*
0.741
31
0.962*
0.746
43
0.903*
0.717
24
0.720
Table 3.5 Maxent SDM results for the eight
shortlist species. The no. of training samples is
the no. of unique presence records used to
calculate each SDM. The null AUC value is the
upper limit of the 95% C.I. of null AUC values.
* indicates the SDM predicts the presence
records significantly better than chance.
A. Annickia affinis
E. Cylicodiscus gabunensis
B. Aucoumea klaineana
F. Drypetes gossweileri
C. Baillonella toxisperma
G. Guibourtia tessmannii
D. Copaifera religiosa
H. Pterocarpus soyauxii
Figure 3.11 A-H Thresholded species distribution models (shown in blue) projected onto a
vegetation cover map of the studied area. The modelled area is 314x168 pixels with a cell
size of 5x5 arcminutes or approx. 9.28x9.28 km at equator
25
Number of SDM cells
0
5000
Annickia affinis
32%
Aucoumea klaineana
80%
40%
Copaifera religiosa
91%
77%
16%
53%
18%
cells of SDM in Gabon
10000
15000
20000
cells of SDM not in Gabon
Figure 3.12 SDM area within and outside Gabon. The units are raster cells of 5x5 arcminutes, which is approx.
9.28x9.28 km at the equator. Dark green coulour and numbers in white indicate the percentages of total area that lay
within Gabon
Figure 3.11 A-H on the previous page shows the thresholded Maxent species distribution models (in
blue) for all eight species on the shortlist. They show that the theoretical species distributions
differed to a great extent between species, in total area and the percentages of those areas that lay
in Gabon. This is confirmed by figure 3.12, which compares total SDM areas and also shows how
much of the SDM lay within Gabon (in dark green and the percentages in white). Especially the
species Copaifera religiosa (91%), Aucoumea klaineana (80%), and Cylicodiscus gabunensis (77%)
had almost all of their distribution in Gabon. Guibourtia tessmannii (53%), Baillonella toxisperma
(40%) and Annickia affinis (32%) were more widespread but still had a large part of their
distribution in Gabon. Pterocarpus soyauxii (18%) and Drypetes gossweileri (16%) were mostly
located outside of Gabon.
Besides looking at the full distribution models and to what extent these distributions lay in Gabon,
we also looked more closely at the situation within Gabon with respect to future availability of the
shortlist species. The map in figure 3.13 shows the general situation of Gabon with regard to area
allocated to conservation (National Parks) and timber extraction (logging concessions). All SDMs
(within Gabon) were compared to these areas to assess the amount of each SDM located within
and outside of protected areas and concessions. The results of this comparison are shown in figure
3.14, which shows the relative and absolute values of the SDM cells within Gabon that were located
in or outside protected areas (National Parks) and logging concessions. Of the total Gabonese
terrestrial area, 11% was designated as protected area, 44% was in a logging concession and the
remaining 44% was in neither but could be urban area or degraded forest.
26
Figure 3.13 Map showing the (rasterised)
National Parks and logging concessions
in Gabon. The rasters have the same
resolution as the SDMs to be able assess
overlap.
Relatively, the species did not differ to a great extent from each other or Gabon in total: on
average, 10% of the SDM area was located within National Parks (8.8 to 11.0%). There was more
variation in the amount of SDM cells within logging concessions, averaging at 47.3%, D. gossweilerii
forming the lower limit at 44.7% (which was still more than Gabon in total) and C. gabunensis
having the maximum with 50.5% of its total SDM area in concessions. It should be kept in mind,
however, that although the percentages might have been comparable between species, the
absolute amounts differed greatly depending on the total size of an SDM area.
0%
10%
20%
30%
40%
50%
60%
70%
80%
Annickia affinis
185
Aucoumea klaineana
200
304
1334
1318
Copaifera religiosa
122
514
493
216
322
1348
1343
213
1167
972
318
1315
1266
Gabon total
332
1363
1403
cells of SDM in National Park
1006
1075
1044
cells of SDM in concession
90%
100%
907
898
806
cells not in concession or NP
Figure 3.14 Percentages of SDM area within Gabon that was located in national parks (dark green), logging concessions
(light green) or in neither of those (grey). Numbers in white indicate absolute values, expressed as number of raster
cells (5x5 arcminutes, approx. 9.28x9.28 km at the equator).
27
4. Discussion
Species that were harvested for bark, roots or wood in Gabon varied greatly with regard to a
number of factors that influence sustainability. Many were only sold in small quantities or were
rarely used, some were cultivated or only harvested from degraded land or secondary forest. These
plant species are therefore not likely to be under large pressure due to their harvest for medicine
and are possibly being harvested sustainably. However, for some species the prospects are a lot
less optimistic. These species were harvested from the wild, often grew mainly in primary forest
and were offered for sale in large quantities or were harvested as commercial timber and were
exported on a large scale. Some were already reported by harvesters to be increasingly difficult to
find near Libreville. These species are:
-
Annickia affinis
Aucoumea klaineana
Copaifera religiosa
Baillonella toxisperma and Guibourtia tessmannii are also mentioned by Dijk & Wiersum (2001) as
most vulnerable to conflicting interests and deserving appropriate protection in Cameroon,
because both are major timber species but also important NTFP species.
Our informants claimed that most or all of the species they harvested bark from, were able to
recover. However, Delvaux et al. (2009) found that in West Africa, only two out of 12 researched
medicinal tree species were able to fully recover from bark harvest. This contributes to the doubt
that exists as to whether sustainable commercial harvest of medicinal plants from wild populations
is possible at all (Clark & Tchamou 1998). In Gabon, no effective control mechanism seems to be in
place to guide extraction. Such a mechanism was unnecessary in the past and is still unnecessary in
remote rural areas where traditional practices, tools and taboos limit the pressure on wild plant
populations, but current urbanisation and commercialisation increases the need for some form of
(government) control (Cunningham 1993; Alexiades & Shanley 2004).
Species distribution models showed that especially Copaifera religiosa, Aucoumea klaineana,
Guibourtia tessmannii, Cylicodiscus gabunensis and Baillonella toxisperma had most or a major part
of their theoretical distribution in Gabon. These species therefore depend greatly for their future
on the government and people of Gabon. But even the remaining three species on the shortlist,
although they are wider distributed, could become unavailable for medicinal use by local people in
the future. This is because according to our analysis, Gabon had 11% of its surface area in protected
areas, where medicinal plant harvest is not allowed; 44% (and this might be an underestimation)
was in logging concessions, where many medicinal species (e.g. A. klaineana, B. toxisperma, C.
gabunensis, G. tessmannii and Pterocarpus soyauxii) will likely be logged because they are also
valuable timber species; and the remainder, 45% also includes area that has been logged in the past
or is otherwise degraded.
28
There are several options for improvement of the sustainability of harvest of the shortlisted
species. Although cultivation of pure stands of these species will likely be too expensive (Vermeulen
2006), some species (e.g. Annickia affinis, a secondary forest species) could be suitable for
enrichment plantings in forest edges or disturbed areas. Regulation of wild population harvest
practices, such as amount harvested per tree and rotation, would also promote sustainability. This
would however require elaborate research on the response of the shortlist species to bark removal
to determine the most appropriate harvest regime, in addition to development of a legal
framework and institutional structures (Geldenhuys 2004). Perhaps the most viable short-term
improvement of sustainability would be to promote integrated use of species that provide
medicinal NTFPs and commercial timber (Vermeulen 2006). If logging plans take medicinal plants,
their ecology, value and users into account, the two uses do not have to be contradicting (Clark &
Sunderland 2004). An example of integrated use would be commercial harvesters extracting bark
from trees that are destined to be logged, or after they have been logged (e.g. at sawmills).
4.1 Limitations
Due to time constraints, the market surveys of this research were conducted in a relatively short
timeframe and at a limited amount of locations. Cunningham (2001) has stressed the importance of
longer-term research because some products are only available in certain seasons. Bark, roots and
wood however are generally available year-round, so surveys in other seasons are unlikely to yield
results that are very different. Moreover, the non-seasonality of e.g. bark makes availability
predictable, which is why less organisation and mobilisation of household labour is needed, which
in turn makes the harvest of barks potentially less sustainable (Ticktin & Shackleton 2011).
Another limitation of this research was the difficulty of the identification of many collections. Often
the only available material was a piece of bark and a vernacular name. The matching up of samples
in the field greatly improved identification because leaves could be collected or colour and smell of
exudate could be observed. Still, some collections remained problematic and their identifications
error-prone. We did not find some species, such as Canarium schweinfurthii (aiele, abèl) even
though literature suggests likely presence on the market. This particular species could have been
confused with Cola spp. (abé). However, with the help of many botanical experts, a Leiden wood
anatomist and DNA analysis most of the collections were identified, many up to the species level.
Moreover, I am confident that at least the eight species in the shortlist were identified correctly.
As one of the indicators for harvest intensity, plant use interviews were used. These questionnaires
were solely about diseases related to women’s health and childcare. Of course there are many
more use categories so one could argue that this only provides a limited indication for harvest
intensity. However, women’s health and childcare seem to form a major share of the total uses of
medicinal plants (e.g. 25% of medicinal plants sold on markets in Ghana were used for women’s
health, Van Andel et al. 2012), and they formed a valuable addition to the market surveys, which,
one could argue, reflect nearly the full range of uses.
4.2 Conclusion
Thanks to Gabon’s low population density and extensive forest cover, many medicinal plant species
are likely being harvested sustainably. However, increasing urbanisation and commercialisation of
the trade leads to a high pressure on remaining wild populations of some species, especially near
cities. Additionally, many medicinal tree species (although they might be harvested sustainable for
29
medicine) are also logged on a large scale because of their valuable timber. When one considers
the vast areas of forest that are currently in logging concessions, the future availability of these
species for medicinal harvest is under serious threat. This is bad news, not only for the plant species
themselves, but also for the people that depend on them, for medicine but also for making a living.
Based on the rapid sustainability assessment presented in this report, Baillonella toxisperma and
Guibourtia tessmannii are the top priority species. When the theoretical species distributions are
taken into account, Copaifera religiosa deserves additional attention because of its narrow
distribution which falls almost completely within Gabon. It is advisable to monitor these three
species and devote more research to their ecology and ethnobotany.
30
Aknowledgements
I would like to thank the following funds and foundations, without which this research project
would not have been financially possible: Alberta Mennega Foundation, the Foundation Jo Kolk
Studiefonds, the FONA Foundation for Research on Nature Conservation, and the K.F. Hein Fonds
Studie en Individuele Noden. I also want to thank all the members of the Gabon research team
(Alexandra Towns, Diana Quiroz, Tinde van Andel, Esther van Vliet, Britt Boogmans, and Sofie
Ruysschaert) for their supervision, teaching, physical and moral support. I am also very grateful for
the support we received from botanical experts in the herbariums of Libreville, Wageningen and
Leiden, in addition to the DNA analysts Barbara Gravendeel and Aline Nieman. Finally, I greatly
appreciate the support and cooperation we received from both local and expatriate people in
Gabon, such as all our informants, the Wildlife Conservation Society staff, IPHAMETRA and ANPN
personnel.
31
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34
Appendix 1. DNA analysis report
Samples Gabon
Identification of bark samples
Report by Aline Nieman (NCB Naturalis)
31 May 2013
Project collaborator: Tinde van Andel
Samples
Bark samples DQ988 and AMT924 were extracted for identification with DNA barcoding. DQ988
presumably belongs to the family Menispermaceae and AMT924 presumably to Fabaceae. Therefor
samples from these families were used as positive control in the amplifications.
Extraction
A standard CTAB protocol (Doyle and Doyle 1987) was used for DNA extraction (this is the same
CTAB extraction method previously used to generate barcodes from samples from Benin). Before
grinding the material for extraction, the outer layer of the samples was removed; the samples were
grinded with a mortar and pestle using liquid nitrogen. The final elution was made in 50 µL 1×TE
buffer. From the DNA extract 2 µL was used to measure the concentration and quality of the DNA
extracts on a Nanodrop (Table 1).
Extraction nr.
11
12
Bl1
3.1
3.2
4.1
4.2
Sample name
DQ988
AMT924
Extraction blank
Stephania sp. (Menispermaceae)
Stephania sp. (Menispermaceae)
Maniltoa psilogyne (Fabaceae)
Maniltoa psilogyne (Fabaceae)
ng/µL
38.5
18.3
-1.4
17.51
12.18
23.82
23.95
260/280
0.81
1.23
0.99
2.22
2.01
2.01
1.93
Table 0.1. DNA concentration and quality measurements.
DNA extracts were not available as positive control. Samples were collected in the Hortus Botanicus
of Leiden University. was extracted in duplicate at Markerpoint using the Qiagen DNeasy plant mini
kit. These extracts were given Extract numbers 3,1; 3,2; 4,1 and 4,2.The concentration and quality of
the DNA extracts was measured on a Nanodrop (Table 1).
Amplification
Amplification of intergenic spacer trnL-trnF was performed using forward primer E and reverse
primer F (table 2). The PCR was carried out in 25µl reactions containing 1U Phire hot start II DNA
polymerase, Phire reaction buffer, 1mM MgCl2, 0.1mg/ml BSA, 1% DMSO, 0.05 mM dNTPs, 0.4 µM
of each primer, and 3 µL 1:10 diluted DNA extract.. Amplifications were performed using a 3 min
activation step at 98 °C, followed by 40 cycles at 98 °C for 5 s, 55 °C for 10 s and 72 °C for 30 s, and
a concluding step at 72 °C for 5 min.
Primer Region Dir. Sequence 5’-3’
Reference
E
trnL-F F
GGTTCAAGTCCCTCTATCCC Taberlet, Gielly et al. (1991)
ATTTGAACTGGTGACACGAG Taberlet, Gielly et al. (1991)
F
trnL-F R
Table 0.2. Primer overview
35
Figure 0.1.Eelectrophoresis of PCR product.- = PCR blank; +1: extract 3,1; +2=extract 4,1
PCR products of successful amplifications (figure 1) were sequenced on an ABI3730XL at Macrogen
Europe. Obtained sequences were blasted against NCBI GenBank data for taxonomic identification
(table 3).
Sample
DQ988
AMT924
Sequence length (BP)
395
380
Family
Rubiaceae
Rubiaceae
genus
Pausinystalia
Keetia
Table 0.3. sequence identification
The trnL-F fragment from sample DQ988 is identical to GenBank accession number AJ346946.1;
Pausinystalia lane-poolei subsp. lane-poolei. The first twenty hits on GenBank were downloaded
and a Neighbor joining tree with uncorrected distance and Stephia delavayi as root. In the resulting
tree DQ988 groups with the Pausinystalia sequneces (Figure 2).
The trnL-F fragment from sample AMT924 is identical to Genbank accession numbers AF152655.1;
Polysphaeria sp. and AJ620144.1; Keetia lukei. Additional to the first twenty hits from GenBank, trnLF sequences of both these genera were added to see if these genera grouped together. In a
Neighbor Joining tree with uncorrected distance rooted in midpoint, AMT924 groups with all Keetia
sequences. The Polysphaeria sequences form an outgroup to the rest of the GenBank hits (Figure
3).
References
Doyle, J. J. and J. L. Doyle (1987). "A rapid DNA isolation procedure for small quantities of fresh leaf
tissue." Phytochemical Bulletin 19: 11-15.
Taberlet, P., L. Gielly, et al. (1991). "Universal primers for amplification of three non-coding regions
of chloroplast DNA." Plant molecular biology 17(5): 1105-1109.
36
Figure 0.2. NJ tree of DQ988 and closest GenBank hits.
Figure 0.3. NJ tree of AMT924, 20 closest GenBank hits, 5 Keetia and 2 Polysphaeria.
37
Appendix 2. Market survey results
Table showing the results of market surveys of 23 stalls. Total Weight is the total weight offered for
sale across all surveyed markets, so it is an underestimation of total marketed weight. Fr: French.
Coll.
Number
Family
Species
Local Name
Plant
Part
Total
Weight
(kg)
0.17
0.18
2.72
% of
Stalls
bark
bark
root
No.
Sales
Units
1
2
97
AMT163
AMT738
AMT749,
DQ1111
AMT743
ANAC
ANAC
ANIS
Lannea barteri (Oliv.) Engl.
Pseudospondias longifolia Engl. cf
Anisophyllea sp. AMT749
ANNO
AMT1013
AMT739
ANNO
ANNO
AMT942
ANNO
AMT748
ANNO
AMT750
AMT667
NA
AMT782
AMT740,
AMT1009
AMT750,
AMT1016,
AMT939,
AMT1050
AMT777
AMT786
AMT74,
DQ415
AMT941,
AMT1032
DQ958
ANNO
APOC
APOC
ARAL
BIGN
BURS
Annickia affinis (Exell) Versteegh &
Sosef
Annona sp. AMT1013
Anonidium mannii (Oliv.) Engl. &
Diels
Greenwayodendron suaveolens
(Engl. & Diels) Verdc.
Meiocarpidium lepidotum Engl. &
Diels
Xylopia aethiopica (Dunal) A.Rich.
Alstonia sp. cf AMT667
Tabernanthe iboga Baill.
Panax sp. AMT782
Newbouldia laevis (P.Beauv.)
Seem.
Aucoumea klaineana Pierre
NA
mazunaunbali (Puna)
onong (Fang),
(mu)mbundu (Punu)
bois jaune (Fr), mfo
(Fang)
muyoha (Punu)
yinda (Masongo)
bark
156
25.94
35
bark
bark
5
5
0.24
0.29
4
4
otunga (Fang)
root
1
0.03
4
NA
bark
15
0.35
4
torche indigène (Fr)
mukuka (Masongo)
bois sacré (Fr)
Cameroon root
mopintiti (Punu),
onvup (Fang)
okoumé (common,
Punu, Fang), torche
indigène (Fr)
bark
bark
rootbark
root
bark
218
14
23
4
34
12.83
0.73
1.42
0.06
4.43
35
9
26
4
9
bark,
resin,
wood
218
138.69
39
CLUS
CLUS
COMB
Pteleopsis suberosa Engl. & Diels
onyeng (Fang)
esok, esop (Fang)
kuli-kuli goto (Fon)
bark
bark
bark
65
130
5
10.31
13.56
1.36
13
9
4
EUPH
Croton oligandrus Pierre ex Hutch.
ongen (Fang)
bark
60
10.71
13
EUPH
dibula (Masongo)
bark
8
1.44
4
FABA
Plagiostyles africana (Müll.Arg.)
Prain
AMT 665
AMT665
6.1
17
FABA
FABA
Copaifera religiosa J.Leonard
liana
(root)
bark
bark
61
AMT755
DQ960
88
37
21.69
8.18
22
13
AMT757,
AMT1029
AMT785
AMT946
FABA
bark
61
13.69
13
FABA
FABA
Detarium macrocarpum Harms
Dialium guineense Willd. cf
bark
bark
12
10
0.3
2.05
9
4
AMT756,
DQ961
AMT1010,
DQ959
FABA
Distemonanthus benthamianus
Baill.
Erythrophleum ivorense A.Chev.
igamu (Punu), akoha
(Fang)
mutombi (Masango)
mudumu (Punu,
Nzebi)
pangu, mutanghani
(Masongo)
enouk (Fang)
padouk (Fang)
(mistake of seller)
movengi (Masongo),
cinq feuilles (Fr)
mbaka (Punu), bois de
lune (Fr)
bark
71
11.22
17
bark
46
11.13
17
38
FABA
4
4
22
Coll.
Number
Family
Species
Local Name
Plant
Part
Total
Weight
(kg)
6.64
% of
Stalls
bark
No.
Sales
Units
43
AMT668,
AMT764
FABA
J.Leonard
AMT663
NA
FABA
FABA
Piptadeniastrum africanum
(Hook.f.) Brenan
AMT781
DQ1108
AMT1011
FABA
FABA
GELS
DQ1107
AMT778
HUAC
HYPE
AMT1017
IRVI
Scorodophloeus zenkeri Harms
Mostuea hirsuta (T.Anderson ex
Benth.) Baill.
Afrostyrax lepidophyllus Mildbr. cf
Harungana madagascariensis
Lam. ex Poir.
Irvingia gabonensis (AubryLecomte ex O'Rorke) Baill.
obaka (Masongo),
keva (Punu), kevasingo
(commercial)
ebe (Fang)
ntoum/debema
(Fang), musinga
(Masongo)
kaolin rouge (Fr)
ail indigiene (Fr
mwenda (Punu)
bark
bark
9
8
1.01
1.37
4
9
wood
bark
root
105
10
27
9.5
0.4
0.65
35
4
13
ail indigiene de riz (Fr)
atuin (Fang)
bark
bark
10
51
0.16
7.09
13
22
chocolatier (Fr), odika
(Punu), muebe(a)
(Punu)
fromagier (Fr),
mufuma (Punu)
Colatier (Fr),
mbonatzu (Punu)
demarreur noir (Fr)
bark
5
0.44
4
AMT1037
MALV
Ceiba pentandra (L.) Gaertn. cf
bark
7
3.46
4
AMT1015
MALV
AMT753,
AMT783
AMT754
MENI
Cola acuminate (P.Beauv.) Schott
& Endl.
Synclisia scabrida Miers
bark
13
0.7
4
root
31
0.6
17
MORA
Dorstenia psilurus Welw.
petite racine rouge
(Fr)
mubogo (Punu
anong (Fang)
root
73
1.35
22
AMT1012
AMT752,
AMT779
NA
PAND
POLY
Panda oleosa Pierre
Carpolobia alba G.Don
bark
root
8
30
0.38
2.17
4
9
POLY
Carpolobia sp.
kuta (unknown
language)
muyunguo (Masongo)
benzinzao (Punu), bark
of elephant tree
tobu (Punu)
root
6
0.46
4
DQ1061
AMT1014
PUTR
RUBI
AMT747
RUBI
AMT690
NA
DQ986
RUBI
RUBI
RUBI
AMT25
RUBI
AMT1033
RUTA
AMT745
AMT763
NA
AMT1047
AMT940
SAPO
SIMA
NA
NA
NA
Drypetes gossweileri S.Moore
Aoranthe cladantha (K.Schum.)
Somers
Fleroya ledermannii (K.Krause)
Y.F.Deng
Keetia sp.AMT690
Morinda lucida Benth.
Nauclea diderrichii (De Wild.)
Merr.
Sarcocephalus latifolius (Sm.)
E.A.Bruce
Zanthoxylum heitzii (Aubrév. &
Pellegr.) P.G.Waterman cf
Quassia Africana (Baill.) Baill.
"ready made bottle"
AMT1047
AMT940
bark
bark
13
7
9.95
0.46
9
4
bark
35
2.59
4
rata (Nzebi)
NA
muzingo (Masongo)
bark
root
bark
12
5
32
0.7
0.46
0.42
9
4
17
kudo (Fon)
root
5
0.3
4
olong (Fang)
bark
5
1.31
4
moabi (Masango)
zinderal (Punu)
ready-made
seviki (Masongo)
mabaman (Fang)
bark
root
bottle
bark
bark
22
54
22
6
10
1.69
1.51
33
1.28
1.43
13
13
30
4
4
39
22
Appendix 3. Plant use citations
Table showing species and the times cited during plant use interviews conducted by A.M. Towns and E. van
Vliet (Towns forthcoming, Van Vliet 2013).
Species
Annickia affinis (Exell) Versteegh & Sosef
Harungana madagascariensis Lam. ex Poir.
Alstonia boonei De Wild., A. congensis Engl.
Guibourtia tessmannii (Harms) J.Leonard
Pycnanthus angolensis (Welw.) Warb.
Mangifera indica L.
Anonidium mannii (Oliv.) Engl. & Diels
Tetrorchidium didymostemon (Baill.) Pax & K.Hoffm.
Musanga cecropioides R.Br. ex Tedlie
Maesopsis eminii Engl.
Picralima nitida (Stapf) T.Durand & H.Durand
Petersianthus macrocarpus (P.Beauv.) Liben
Piptadeniastrum africanum (Hook.f.) Brenan
Theobroma cacao L.
Irvingia gabonensis (Aubry-Lecomte ex O'Rorke) Baill.
Anthocleista nobilis G.Don
Ficus exasperata Vahl
Citrus aurantifolia (Christm.) Swingle
Myrianthus arboreus P.Beauv.
Pseudospondias longifolia Engl.
Macaranga spinosa Müll.Arg.
Plagiostyles africana (Müll.Arg.) Prain
Distemonanthus benthamianus Baill.
Ficus thonningii Blume
Citations
30
25
22
18
15
13
12
10
10
10
9
9
7
7
6
6
6
6
6
5
5
5
5
4
4
4
4
4
3
3
3
3
3
3
Milicia excelsa (Welw.) C.C.Berg
Musa sp.
Quassia africana (Baill.) Baill.
Annickia sp.
Annona muricata L.
Funtumia africana (Benth.) Stapf
Carica papaya L.
Vernonia conferta Benth.
Croton mayumbensis J.Léonard
Macaranga saccifera Pax
3
3
3
2
2
2
2
2
2
2
Afrostyrax sp.
Albizia glaberrima (Schum. & Thonn.) Benth.
2
2
40
Species (cont.)
Millettia mannii Baker
Ceiba pentandra (L.) Gaertn.
Cola sp.
Ficus mucuso Welw. ex Ficalho
Treculia erinacea A.Chev.
Fleroya ledermannii (K.Krause) Y.F.Deng
Sarcocephalus latifolius (Sm.) E.A.Bruce
Leea guineense G.Don
Dracaena fragans (L.) Ker Gawl.
Trichoscypha sp.
Annona senegalensis Pers.
Cleisthopholis sp.
Caloncoba welwitschii (Oliv.) Gilg
Asparagus warneckei (Engl.) Hutch.
Santiria trimera (Oliv.) Aubrév.
Ageratum conyzoides (L.) L.
Vernonia amygdalina Delile
Ipomoea mauritiana Jacq.
Cogniauxia podolaena Baill.
Tetracera sp.
Acalypha paniculata Miq.
Alchornea floribunda Müll.Arg.
Croton oligandrus Pierre ex Hutch.
Manihot esculenta Crantz
Anthocleista vogellii Planch.
Persea americana Mill.
Berlinia bracteosa Benth.
Pentaclethra sp.
Pentaclethra eetveldeana De Wild. & T.Durand
Cola nitada (Vent.) Schott & Endl.
Cola sp.
Perichasma laetificata Miers
Scyphocephalium ochocoa Warb.
Staudtia kamerunensis var. gabonensis
(Warb.) Fouilloy
Boerhavia diffusa L.
Panda oleosa Pierre
Barteria fistulosa Mast.
Cymbopogon sp.
Carpolobia sp.
Carpolobia lutea G.Don
Drypetes sp.
Aoranthe cladantha (K.Schum.) Somers
Leptactina mannii Hook.f.
Zanthoxylum heitzii (Aubrév. & Pellegr.)
P.G.Waterman
Thomandersia sp.
Cecropia peltata L.
Citations
2
3
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Appendix 4. Plant species with sustainability scores
Coll.
Number
AMT746
AMT958
AMT163
Plant
Part
Fam.
Species
ANAC
ANAC
AMT738
ANAC
AMT749
DQ1111
ANIS
AMT743
ANNO
AMT1013
ANNO
AMT739
ANNO
AMT942
ANNO
AMT748
ANNO
AMT750
ANNO
AMT667
APOC
Harvest intensity
Abundance
Veg.
Type
Cult.
Status
Other
Uses
Total
Avg.
5
3
4
5
4
26
3.7
1
1
3
2
5
4
20
2.9
4
1
4
3
2
5
3
22
3.1
5
4
1
3
3
5
3
24
3.4
4
5
5
5
2
5
4
30
4.3
4
1
1
3
3
3
3
18
2.6
4
1
5
3
1
1
4
19
2.7
5
1
1
1
4
5
4
21
3
4
2
1
1
4
5
3
20
2.9
4
5
3
3
2
5
4
26
3.7
4
3
5
1
2
5
4
24
3.4
Total
Weight
Citations
4
1
Lannea barteri (Oliv.) Engl.
Pseudospondias longifolia Engl.
cf
Anisophyllea polyneura Floret
cf
Annickia affinis (Exell)
Versteegh & Sosef
4
Annona sp. AMT1013
APOC
Anonidium mannii (Oliv.) Engl.
& Diels
Greenwayodendron suaveolens
(Engl. & Diels) Verdc.
Meiocarpidium lepidotum Engl.
& Diels
Xylopia aethiopica (Dunal)
A.Rich.
Alstonia boonei, A. congensis
Engl. cf AMT667
5
3
4
2
4
1
3
22
3.1
AMT782
ARAL
Panax sp. AMT782
5
1
1
3
3
3
3
19
2.7
AMT740
AMT1009
BIGN
Newbouldia laevis (P.Beauv.)
Seem.
4
4
1
3
2
3
3
20
2.9
AMT750
AMT1016
AMT939
AMT1050
BURS
5
5
4
4
2
5
5
30
4.3
AMT777
CLUS
4
5
1
4
2
1
4
21
3
AMT786
AMT74
DQ415
CLUS
Pteleopsis suberosa Engl. &
Diels
Croton oligandrus Pierre ex
Hutch, C. mayumbensis
J.Léonard
Plagiostyles africana
(Müll.Arg.) Prain
Bobgunnia fistuloides (Harms)
J.H.Kirkbr. & Wiersema
4
5
4
3
2
5
4
27
3.9
4
3
1
3
3
5
4
23
3.3
4
5
4
3
2
5
4
27
3.9
4
3
4
1
2
5
4
23
3.3
4
1
1
4
4
5
4
23
3.3
COMB
AMT941
AMT1032
EUPH
DQ958
EUPH
DQ987
FABA
AMT755
FABA
Copaifera religiosa J.Leonard
4
5
1
5
5
5
4
29
4.1
DQ960
FABA
4
4
5
5
4
5
5
32
4.6
AMT757
AMT1029
FABA
4
5
1
4
4
5
4
27
3.9
AMT785
FABA
Detarium macrocarpum Harms
4
1
1
4
2
5
4
21
3
AMT946
FABA
Dialium guineense Willd. cf
4
4
1
1
2
5
3
20
2.9
41
Coll.
Number
Fam.
Species
AMT756
DQ961
FABA
Distemonanthus benthamianus
Baill.
AMT1010
DQ959
FABA
Erythrophleum ivorense
A.Chev.
AMT668
AMT764
FABA
AMT663
FABA
Plant
Part
Harvest intensity
Abundance
Veg.
Type
Cult.
Status
Other
Uses
Total
Avg.
4
2
2
5
5
27
3.9
5
1
1
2
5
4
22
3.1
4
4
5
5
5
5
5
33
4.7
4
3
5
2
4
5
4
27
3.9
4
3
4
4
2
5
5
27
3.9
5
4
5
4
4
5
5
32
4.6
Total
Weight
Citations
4
5
4
AMT781
FABA
J.Leonard
Pentaclethra macrophylla
Benth.
Piptadeniastrum africanum
(Hook.f.) Brenan
DQ1108
FABA
Scorodophloeus zenkeri Harms
4
2
3
1
4
5
4
23
3.3
AMT665
FABA
5
4
1
3
3
3
3
22
3.1
AMT1011
GELS
5
2
1
2
2
5
3
20
2.9
DQ1107
HUAC
4
1
3
5
2
5
4
24
3.4
AMT778
HYPE
4
4
5
1
2
4
4
24
3.4
AMT1017
IRVI
sp. AMT 665
Mostuea hirsuta (T.Anderson
ex Benth.) Baill.
Afrostyrax lepidophyllus
Mildbr. cf
Harungana madagascariensis
Lam. ex Poir.
Irvingia gabonensis (AubryLecomte ex O'Rorke) Baill.
4
2
4
4
2
4
4
24
3.4
AMT1037
MALV
Ceiba pentandra (L.) Gaertn. cf
4
4
4
2
2
5
4
25
3.6
AMT1015
MALV
Cola acuminata (P.Beauv.)
Schott & Endl.
4
2
4
3
2
5
4
24
3.4
MENI
Synclisia scabrida Miers
5
2
1
3
2
5
3
21
3
MORA
Dorstenia psilurus Welw.
5
3
1
3
2
5
3
22
3.1
AMT1012
PAND
Panda oleosa Pierre
4
2
3
1
5
5
4
24
3.4
AMT752
AMT779
POLY
5
4
5
1
2
5
4
26
3.7
FABA
AMT753
AMT783
AMT754
POLY
Carpolobia sp.
5
2
1
3
3
3
3
20
2.9
DQ1061
PUTR
4
5
3
5
4
5
3
29
4.1
AMT1014
RUBI
4
2
3
3
2
5
3
22
3.1
AMT747
RUBI
4
4
3
4
2
5
4
26
3.7
AMT690
RUBI
Drypetes gossweileri S.Moore
Aoranthe cladantha (K.Schum.)
Somers
Fleroya ledermannii (K.Krause)
Y.F.Deng
Keetia sp.AMT690
4
2
3
3
3
3
3
21
3
5
2
5
2
2
5
4
25
3.6
4
2
1
5
2
5
5
24
3.4
5
1
3
1
2
5
4
21
3
4
3
3
3
2
5
4
24
3.4
RUBI
DQ986
RUBI
AMT25
RUBI
AMT1033
RUTA
AMT745
SAPO
Nauclea diderrichii (De Wild.)
Merr.
Sarcocephalus latifolius (Sm.)
E.A.Bruce
Zanthoxylum heitzii (Aubrév. &
Pellegr.) P.G.Waterman cf
4
4
5
5
5
5
5
33
4.7
AMT763
SIMA
Quassia africana (Baill.) Baill.
5
3
4
3
4
5
3
27
3.9
AMT940
AMT1047
NA
NA
NA
NA
4
4
3
3
1
1
3
3
3
3
3
3
3
3
20
20
2.9
2.9
42

L Guinee MSc thesis

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