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We execute tree `domestication' as a farmer-driven and market-led process, which matches the intraspecific diversity of locally important trees to the needs of subsistence farmers, product markets, and agricultural environments. We propose that the products of such domesticated trees are called Agroforestry Tree Products (AFTPs) to distinguish them from the extractive tree resources commonly referred to as non-timber forest products (NTFPs). The steps of such a domestication process are: selection of priority species based on their expected products or services; definition of an appropriate domestication strategy considering the farmer-, market-, and landscape needs; sourcing, documentation and deployment of germplasm (seed, seedlings or clonal material); and tree improvement research (tree breeding or cultivar selection pathways). The research phase may involve research institutions on their own or in participatory mode with the stakeholders such as farmers or communities. Working directly with the end-users is advantageous towards economic, social and environmental goals, especially in developing countries. Two case studies (Prunus africana and Dacryodes edulis) are presented to highlight the approaches used for medicinal and fruit-producing species. Issues for future development include the expansion of the program to a wider range of species and their products and the strengthening of the links between product commercialization and domestication. It is important to involve the food industry in this process, while protecting the intellectual property rights of farmers to their germplasm.
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Agroforestry Systems 61: 167–181, 2004.
© 2004 Kluwer Academic Publishers. Printed in the Netherlands. 167
Tree domestication in tropical agroforestry
A.J. Simons1,and R.R.B. Leakey2
1World Agroforestry Centre, United Nations Avenue, P. O. Box 30677-00100, Nairobi, Kenya; 2Agroforestry and
Novel Crops Unit, School of Tropical Biology, James Cook University, Cairns, Australia QLD 4870; Author for
correspondence: e-mail: t.simons@cgiar.org
Key words: Agroforestry tree products (AFTPs), Dacryodes edulis, Genetic improvement, Participatory appraisal,
Prunus africana, Tree breeding
Abstract
We execute tree ‘domestication’ as a farmer-driven and market-led process, which matches the intraspecific
diversity of locally important trees to the needs of subsistence farmers, product markets, and agricultural environ-
ments. We propose that the products of such domesticated trees are called Agroforestry Tree Products (AFTPs) to
distinguish them from the extractive tree resources commonly referred to as non-timber forest products (NTFPs).
The steps of such a domestication process are: selection of priority species based on their expected products or
services; definition of an appropriate domestication strategy considering the farmer-, market-, and landscape needs;
sourcing, documentation and deployment of germplasm (seed, seedlings or clonal material); and tree improvement
research (tree breeding or cultivar selection pathways). The research phase may involve research institutions on
their own or in participatory mode with the stakeholders such as farmers or communities. Working directly with the
end-users is advantageous towards economic, social and environmental goals, especially in developing countries.
Two case studies (Prunus africana and Dacryodes edulis) are presented to highlight the approaches used for
medicinal and fruit-producing species. Issues for future development include the expansion of the program to a
wider range of species and their products and the strengthening of the links between product commercialization
and domestication. It is important to involve the food industry in this process, while protecting the intellectual
property rights of farmers to their germplasm.
Introduction
Tree domestication is an umbrella term that is often
applied erroneously to a subset of activities such as
provenance testing or to a narrow application such
as industrial forestry. Simply put, tree domestication
refers to how humans select, manage and propagate
trees where the humans involved may be scientists,
civic authorities, commercial companies, forest dwell-
ers or farmers. In the tropics, the trees involved in
tree domestication occur in natural forest, secondary
forest, communal fallow lands, plantations and farms.
These trees in turn provide both products (timber, fruit,
fodder, etc.) and services (shade, soil improvement,
erosion control, etc.). Of course, human history is
interwoven with forests and trees before agriculture,
urbanisation and commerce began, but until relatively
recently the interaction was about extraction of tree
products from natural forests.
While much is written about natural forest man-
agement, commercial tree improvement and forest
analogue systems, relatively less is published on the
largest group of people who are the rural population
in developing countries and their interactions with
the large group of tree species in agricultural land-
scapes. In Asia, Latin America, Africa, and Oceania
this is where the greatest potential exists for tree do-
mestication to contribute to sustainable development.
Agriculture and forestry are no longer thought of as
mutually exclusive activities, yet national and interna-
168
tional statistics are only kept on the differentiated land
cover of these systems and the data on the extent of
integrated agroforestry systems are not available.
Pantropically, there has been deliberate selection
and management of trees by humans in forests to
provide what are now collectively termed non-timber
forest products (NTFPs). In several cases, the extrac-
tion, and often overextraction of NTFPs has led to
market expansion and supply shortages, which in turn
has led to cultivation of trees for the same products.
The ambiguity arises, however, in that such products
are no longer from the forest and some of the species
also provide valuable timber (e.g. the medicinal spe-
cies Prunus africana). The authors therefore suggest
that a new term is required to define tree products that
are sourced from trees cultivated outside of forests.
Most logically these should be referred to as Agro-
forestry Tree Products (AFTPs). This paper describes
the beginnings, current status and future directions of
domestication of trees for the agroforestry systems of
the tropics with a focus on those providing AFTPs.
Origins and concepts of domestication
The word domestication has had several definitions
and interpretations since its first appearance in the
English language in 1639 (OED 1989). When ap-
plied to animals it refers quite narrowly to taming
wild subjects and bringing them into the homestead.
With respect to plants, there is a spectrum of meaning
from nurturing wild plants through to plant breed-
ing through to genetic modification in vitro. Most
commonly the word is used with reference to an-
nual food crop plants that have undergone selection,
breeding and adaptation in agricultural systems. Ar-
chaeologists concur that annual crop domestication
began with wheat 10 000 years ago in Eurasia at a time
of rising human populations and over-exploitation of
local resources (Simmonds 1979). Cereal domestica-
tion surely ranks as one of the greatest technological
advances in human history since not only does wheat
(Triticum aestivum) still provide 20% of food calories
consumed globally but domestication of other cer-
eal crops (e.g. rice [Oryza sativa], barley [Hordeum
vulgare], maize [Zea mays]) has seen human popu-
lations increase 1000-fold since domestication started
(Diamond 2002).
Tree domestication is a far more recent phe-
nomenon than annual-crop domestication. One of the
earliest records of tree domestication is that of ma-
nipulating pollination in Ficu s trees 2800 years ago
by the prophet Amos (Dafni 1992). More important
though than the date of onset of domestication in trees
is the scale of activity. In terms of conventional im-
provement, tree species are far more neglected today
than agricultural crops, with the exception of temper-
ate fruit trees (Janick and Moore 1996). In commercial
forestry, fewer than 40 taxa have genetic improvement
programs underway and most of these are less than
60 years old (Barnes and Simons 1994). Attempts
at improving the N2-fixing agroforestry species (e.g.,
Leucaena) started even later, in the 1980s, coincid-
ing with concerns about soil fertility management, a
tropical fuelwood crisis, and renewed interest in social
forestry. Domestication of other agroforestry trees has
received substantial recent interest following a num-
ber of articles and conferences, most significantly the
1992 IUFRO Conference in Edinburgh, UK (Leakey
and Newton 1994). Much of the progress in tree do-
mestication has been informed by the well-described
homegarden systems of the Amazon, Southeast Asia
and Africa (Kumar and Nair 2004). Domestication of
trees for the provision of AFTPs has, however, been
more frequently equated to conventional timber-tree
improvement and horticultural improvement than to
homegarden domestication.
Three striking differences between conventional
timber-tree improvement and agroforestry-tree im-
provement exist. These are the number of taxa in-
volved, the industrial rather than subsistence use and
the number of stakeholders involved. Commercial
plantations typically handle one or a few species and
one company may control all the operations from plan-
ning, germplasm sourcing, tree improvement, nursery
management, planting, tree husbandry to harvesting.
These operations are all carried out at a scale to max-
imize profit. In contrast, agroforestry is concerned
with thousands of tree species and millions of sub-
sistence farmer clients influenced by a mixture of
government, private sector, community and interna-
tional partners, each engaged in different and largely
uncoordinated activities. In most cases, agroforestry
tree improvement has been concerned with on-farm
use of firewood, fodder, fruit, live fence, medicinal
and fallow trees. The next large change in agro-
forestry worldwide, which has already started (Franzel
et al. 2004), will probably come from a greater fo-
cus on cultivating trees for cash, and most likely for
fruit, timber and medicines. Thus it is inappropriate
to simply equate agroforestry-tree domestication with
industrial-tree improvement since aspects of species
169
prioritization, indigenous knowledge, farming systems
improvement, adoption and marketing are as import-
ant as selection and multiplication. For these reasons,
the World Agroforestry Centre introduced a wider
concept of tree domestication:
Domesticating agroforestry trees involves bringing
species into wider cultivation through a farmer-
driven and market-led process. This is a science-
based and iterative procedure involving the iden-
tification,production,management and adoption
of high quality germplasm. High quality ger-
mplasm in agroforestry incorporates dimensions
of productivity, fitness of purpose, viability and
diversity. Strategies for individual species vary
according to their functional use, biology, man-
agement alternatives and target environments. Do-
mestication can occur at any point along the con-
tinuum from the wild to the genetically trans-
formed state. The intensity of domestication activ-
ities warranted for a single species will be dic-
tated by a combination of biological, scientific,
policy, economic and social factors. In tandem
with species strategies are approaches to domest-
icate landscapes by investigating and modifying
the uses, values, interspecific diversity, ecological
functions, numbers and niches of both planted and
naturally regenerated trees. (Simons 2003a).
This rather wordy concept can be simplified to:
tree domestication in agroforestry is farmer-driven and
about matching the intra-specific diversity of many
locally important tree species to the needs of subsist-
ence farmers, the markets for a wide range of products
and the diversity of agricultural environment.
Traditionally utilized extractive resources, such as
fruits, medicines, and fibres from forests have been
collectively described as Non-Timber Forest Products
(NTFPs) or Non-Wood Forest Products (NWFPs).
Much research has been done on these products in
the hope of finding better ways of managing and con-
serving natural forests while also benefiting the people
living in or near the forests. Now there is confu-
sion in the statistics and literature as people describe
and discuss these same products as new crops from
farmland (Belcher 2003). It is therefore proposed that
the products of domesticated agroforestry trees, in-
cluding timber, should be called Agroforestry Tree
Products (AFTPs) to distinguish between the wild and
the domesticated products.
Objectives of tree domestication
Trees occur naturally in forests and rangelands and
can be grown in commercial plantations and on farms.
Within the tropics, natural forests cover 35% of the
land; commercial tree plantations account for 1% of
the land cover, tree crop plantations [such as cacao
(Theobroma cacao), rubber (Hevea brasiliensis), tea
(Camelia sinensis), coffee (Coffea spp.), citrus (Cit-
rus spp.), mango (Mangifera indica), and oil palm
(Elaeis guineensis)) account for a further 1.5%; and
agricultural land accounts for 40% of the land area
(FAO 2002). With current tropical deforestation rates
at around 1%, principally for expansion of agricul-
tural areas, and even with the most optimistic increases
in timber-plantation estates (FAO 2003), the largest
scope for future tree planting in the tropics will be on
agricultural land (Simons et al. 2000a).
In agroforestry, the objective of domestication is to
enhance the performance of trees in terms of improved
tree products, such as timber, fruits, and medicines,
and/or improved environmental services, such as the
amelioration of soil fertility. In the former case, im-
provements will usually be for yield and/or quality
with a specific market opportunity as the driver of
genetic selection. The demands for these outputs of
tree domestication in agroforestry trees are sure to at-
tract increasing interest and resources over the coming
decades, and to have an increasing market orientation.
The scale and direction of tree domestication
in agroforestry is dependent upon the varying ob-
jectives of different stakeholders. As already men-
tioned, in most situations in the past, the objective
has been for subsistence use and less frequently for
income generation. However, to date, implementation
of tree ‘needs assessment’ and the consideration of
actual or potential contributions of trees to household
budgets has been inadequate (Njenga and Wesseler
1999), and in many locations the relative importance
of trees, let alone opportunities for tree domestication,
has not been established. Nevertheless, exercises in
tree-species prioritization have been carried out quite
extensively, as described below.
Selection of tree species
Whilst species of only three genera (Acacia, Pinus
and Eucalyptus) account for more than 50% of all
tropical tree plantations (FAO 2003), more than 3000
tree species have been documented in agroforestry
systems (Burley and von Carlowitz 1984). Until the
170
1990s, research priorities amongst this vast array of
agroforestry trees were determined arbitrarily, often
based on individual interests of researchers. Recogni-
tion of the importance of understanding of user needs
and preferences, technological opportunities and sys-
tematic methods for ranking species emerged with
publication of guidelines for tree species priority-
setting procedures (Franzel et al. 1996). Regional
surveys of agroforestry-tree species prioritization have
subsequently been completed for the Sahel, south-
ern Africa and West Africa (Jaenicke et al. 1995;
Sigaud et al. 1998; Maghembe et al. 2000), as well as
for individual countries including Bangladesh, Brazil,
Ghana, India, Indonesia, Peru, Philippines, and Sri
Lanka (e.g., Sotelo and Weber 1997; Lovett and Haq
2000). Species priorities depend on the objectives of
domestication, and will differ if it is for income gen-
eration, satisfying farm household needs, germplasm
conservation through use, forest conservation through
enrichment planting or farm diversification.
Trees found on farms may originate from forest
remnants, natural regeneration or deliberate plant-
ing. Much of the deliberate planting of indigenous
trees on farm [such as the Indonesian damar (Shorea
javanica), cinnamon (Cinnamomum spp.) and rub-
ber agroforests – Michon and de Foresta 1996] arose
because of spontaneous farmer initiatives, while gov-
ernment and donor projects tended to promote exotic
species (see Shanks and Carter 1994). Recent stud-
ies of the frequency and abundance of trees on farms
in Cameroon, Kenya, Nigeria and Uganda show the
balance between indigenous and exotic tree species in
these new plantings (Kindt 2002; Schreckenberg et al.
2002b).
Whilst indigenous taxa may account for the ma-
jority of species on farm, introduced exotic taxa ac-
count for the many of the trees on farm, especially
in Africa. Exotics can have some advantages such as
superior growth, although they also have several risks
including weediness and aggressive use of natural re-
sources. The existence of exotics clearly demonstrates
deliberate planting. Certain exotics have been planted
for decades or centuries such that local communit-
ies consider the naturalized populations as indigenous
species. Examples include Grevillea robusta in Kenya
or Gliricidia sepium in Sri Lanka (Harwood 1992;
Stewart et al. 1996). Whether exotic, naturalized or
indigenous it is clear that many agricultural land-
scapes may be tree rich, but species poor (frequently
within-species diversity, especially in exotic species,
is dangerously poor – Lengkeek et al. in press). For
this reason improvement of the landscape by examin-
ing and ameliorating tree species diversity within and
between functional uses (e.g. boundary, fodder, fire-
wood, and fruit) can be as important as improvement
of a single species. Thus the concept of domesticating
the landscape becomes relevant. Four points of inter-
vention are relevant here: replacement, substitution,
expansion and better management of trees.
In conventional forestry, a classic step in tree im-
provement is derivation of a shortlist of fast-growing
and productive species, which is often arrived at from
species elimination trials. Early work in agroforestry
included such trials, either as unreplicated arboreta or
as replicated trial series (Stewart et al. 1992). Sadly,
much of this research was undocumented and/or dis-
continued, and this has resulted in agroforestry tree
plantings relying on fewer commonly known spe-
cies. Another common shortcoming of this work, even
when it was written up, is that seed sources that were
used to represent species are not reported. This means
that many of the results of species trials are confoun-
ded by the seed source used and species ranking may
have been different had other or mixed sources been
used. The solutions to this shortcoming include: (1)
clear documentation of germplasm used; (2) use of
multiple provenances per species, where possible; (3)
or, when (2) is not possible, inclusion of more than
one provenance to consider a provenance mixture in
species elimination and species proving trials.
Tree domestication strategies
The determinants of a sound domestication strategy
for an individual species can be grouped under 14
headings. These are:
Reasons for domestication (home use, market, con-
servation of the species, agroecosystem diversifica-
tion, improved livelihood strategies)
Tree uses required (products [AFTPs] and services)
History and scale of cultivation (as native and
exotic)
Natural distribution, intraspecific variation and eco-
geographic survey information
Species biology (reproductive botany, ecology, in-
vasiveness)
Scale and profile of target groups and recommenda-
tion domains (biophysical, market, cultural)
Collection, procurement or production of ger-
mplasm and knowledge (including ownership, attri-
bution, benefit sharing, access and use)
171
Propagule types (including symbionts) envisaged
Nursery production and multiplication
Tree productivity (biomass, timing, economics,
risks)
Evaluation – scientific and farmer participatory
Pests and diseases
Genetic gain and selection opportunities, methods
and intensities
Dissemination, scaling up, adoption and diffusion
The problem with most agroforestry tree species
is that information is incomplete, which has led to
suboptimal tree domestication strategies. While tree
domestication work has increased within agroforestry,
the documentation of the logic and the approach has
been generally scant. Even when results are shared
or published, it is typically the outcomes that are
reported and not the processes. A few case studies
of tree domestication strategies are available (e.g.,
Prunus africana; Simons et al. 2000b) as well as
a generic tree domestigram. What is most needed
and lacking, however, is a generalized domestication
decision-framework, which uses the elements of the
domestigram. Case studies of various tree categories
(product type, mode of propagation, generation in-
terval) are currently being used to construct such a
framework.
Beyond the individual tree species domestication
work to meet the needs of the farmer, the market (with
and without processing to enhance shelf life and mar-
ket value), there are several elements to consider for
landscape-level domestication:
Likelihood of interaction of planted trees with nat-
ural populations and consequences of introducing
external populations;
Primary and multiple uses of the species since in-
dividual species differ in the number of total uses
and their primary and secondary uses to different
clients, and lack of attention to this has led to the
miracle species concepts associated with species
such as Leucaena leucocephala;
Combined value of all species (economic, social,
biological) in the landscape;
Diversity (within and between species) in each
functional use group since some groups, e.g. fodder,
may be dominated by a single species and substi-
tution of species in one use group may be more
useful than replacement of existing species with
better material of the same species;
Number of trees per unit area and per farm as in-
formed by considerations of species richness and
abundance;
Niche integration on farm and within the landscape
as it will affect the viability of populations.
A wider consideration of other elements of agrobi-
odiversity, such as soil biota, is also pertinent and may
need attention.
Germplasm sourcing, documentation, and
deployment
One of the most fundamental elements of a tree do-
mestication program is the sourcing and deployment
of germplasm. This is especially true in agroforestry
since little or no formal selection and breeding are
generally carried out. The introductions made on farm
(native and exotic) are in many cases a once-off exer-
cise with subsequent generationsderived by the farmer
from the original parent stock. While subsequent intro-
ductions by farmers may broaden the genetic material,
considerations of the diversity in founder stock are
rarely considered. It is routinely reported from various
authors that seed availability is a significant bottleneck
to tree planting. Perhaps these statements could be
better phrased as ‘seed supply and demand in agro-
forestry are poorly understood and poorly matched.
In essence, the key missing information is the quanti-
fication of the various flows (Figure 1) of each species
between sources, suppliers, and users of germplasm.
The collection of germplasm from wild stands
and the distribution of seed from National Tree Seed
Centres and scientists (FAO 2001; Harwood 1997;
Figure 1) have been best described. One feature evid-
ent from the literature and agroforestry practice is
that most people differentiate between seeds and seed-
lings. To generalize, seeds are seen as the domain
of centralized seed centres, and seedlings are seen
as the mandate of decentralized small-scale nursery
operators.
Herein lies the heart of the ‘disconnect’ in agro-
forestry. The Tree Seed Suppliers Directory (Kindt
et al. 2003) seeks to contribute to understanding of the
availability from a wider set of international seed deal-
ers, but the companion volumes of small-scale seed
producers and nursery operators are missing. For most
species, little information is available and the funda-
mental gap in completing the summary in Figure 1 is
the lack of quantitative data to place against each flow,
as well as details on the number of actors and volumes
of germplasm – whether for a single species, a species
group or trees in general. Against this background, a
new approach in which farmers or village communit-
172
Figure 1. Diagram showing flows between sources, suppliers and users of agroforestry-tree germplasm.
ies develop cultivars from the superior trees in their
own land is being developed by World Agroforestry
Centre within its Participatory Domestication model
(Tchoundjeu et al. 1998; Leakey et al. 2003). This
therefore involves a much more localized/internalised
selection of germplasm.
As with all other plant species, trees became sub-
ject to new international regulations with the coming
into force of the Convention on Biological Diversity
in December 1993. Most importantly national legisla-
tion stipulates how access to and benefit sharing from
plant genetic resources should be handled. In the main,
trees have not undergone the same level of scrutiny
from advocacy groups or government watchdogs as
commercial crop or medicinal plants. This is partly
explained by the lack of commercial interest from seed
multinationals, and also by the lack of harmonization
of national laws on genetic resources of agricultural
species and those on forest genetic resources. To be
able to regulate germplasm it needs to be well de-
scribed. Descriptors provided for germplasm of vari-
ous annual crops allow plant breeders and others to
value and morphologically characterize the materials
developed. Such descriptors for agroforestry trees are
nonexistent. Interestingly, molecular characterization
has been more frequent for agroforestry species and
in particular for the leguminous taxa, including those
within the genera: Acacia,Calliandra,Gliricidia,
Inga,Leucaena and Sesbania, although this approach
is gathering momentum for some timber (e.g., Swiet-
enia macrophylla – Novick et al. 2003) and indigenous
fruit trees (Irvingia gabonensis – Lowe et al. 1998;
2000).
Two contrasting foci have emerged in the agro-
forestry tree seed industry. First there has been
the need to satisfy immediate seed requirements for
donor, non-governmental-organization- (NGO) and
government-led projects. This relies on sizeable pro-
curement activities and in a few cases large-scale seed
production, and the seed is typically given away to
farmers and communities for free. Two negative con-
sequences of this approach have been that farmers
have undervalued the seed as it has been given out
free, and small-scale seed producers have not been
able to expand, as they cannot compete against a free
good. However, a case could be made that if tree cul-
tivation is considered desirable for society then tree
establishment should be subsidized. The second force
173
has been initiatives by the Danish Forest Seed Centre
and others to diagnose and establish sustainable seed
supply systems. These initiatives are not well suited
to project formats where indicators of success can be
reported after two to three years. However, if more
work is not put into sustainable seed systems, the situ-
ation of start-stop tree-seed supply will continue due
to its association with projects. One way to increase
the functionality of seed systems may be with im-
proved material. Often users of tree germplasm do not
differentiate within a species and labelling improved
provenances, varieties, families or clones would assist.
Whether seed will come from project start up activ-
ities or sustainable supply systems there is a need
for accurate demand forecasting of what type, where,
when and how much seed will be needed. A ‘tree seed
forecaster’ has been developed by Simons that, for a
given species, examines geographic scope for cultiv-
ation, potential target population of farmers, testing
and adoption behavior of early and late adopters, aver-
age farm size, number of trees per farm, reproductive
generation interval and scope for on-farm germplasm
production and domestication.
One peculiarity in agroforestry is that germplasm
is typically viewed as relating to seed. Yet few farm-
ers plant seed since few agroforestry species are
direct sown. The few species that are direct sown
are those that tend to provide services rather than
products, such as live fences, nutrient replenishment,
shade, windbreaks, and erosion control. Thus, to
a farmer germplasm is more about seedlings rather
than seed, since the majority of agroforestry trees
are planted from nursery-raised seedlings originating
from either seed or vegetative propagules. Germplasm
supply is, therefore, as much about seedling supply
as seed supply. Whilst commercial forestry operations
have undertaken substantial research on nurseries and
propagation, far less work has been undertaken for
agroforestry trees. In agroforestry there has mainly
been a focus on the quantity rather than quality of
seedlings (Wightman 1999), although it is now recog-
nized that quality encompasses both physiological and
genetic components. Both Jaenicke (1999) and Wight-
man (1999) describe good practices for research and
community nurseries, while Boehringer et al. (2003)
describe the importance of the social and organiza-
tional aspects of nurseries in addition to the technical
ones.
Tree genetic resources used in agriculture should
ideally receive commensurate funding for conserva-
tion in tune with annual crop plants. Sadly, at the inter-
national level, trees are given a back seat compared to
herbaceous and graminaceous crops, as evidenced by
their exclusion at the 1996 Leipzig, Germany, Confer-
ence on Global Plan of Action for Genetic Resources
for Food and Agriculture. Furthermore the recently
negotiated FAO International Treaty on Plant Genetic
Resources for Food and Agriculture (www.fao.org)
lists only two genera for a multilateral conservation
system (Artocarpus and Prosopis).
Tree improvement research
Tree improvement research has generally been based
on two methods of propagation: sexual or vegetative.
Improved tropical fruit trees are typically vegetatively
propagated using buds, grafts, marcots (air-layers) or
cuttings. Here elite clones of species such as mango,
avocado (Persea americana), tamarind (Tamarindus
indica) and citrus are selected at high intensities for
mass propagation as cultivars. Improved timber trees,
such as eucalypts (Eucalyptus spp.) and poplars (Pop-
ulus spp.), may be propagated by cuttings, or from
seed (e.g., Swietenia macrophylla,Cordia alliod-
ora), in which case cloning may have been used in
a seed orchard phase. Nearly all other agroforestry
trees are propagated by seed, either direct sown or
as nursery grown seedlings. Given this orientation,
tree improvement research has focused both on the
propagation method and on the genetic gains from
selection amongst clones or sexual progeny.
The most advanced tree improvement research that
has been undertaken on any agroforestry tree is that
carried out on Leucaena species by Brewbaker and
colleagues at the University of Hawaii (Brewbaker
and Sorensson 1994) during the 1970s to late 1990s.
Leucaena leucocephala is atypical with respect to its
self-mating system, thus making it easy to fix elite
traits. The backcrossing and interspecific hybridiza-
tion carried out by Brewbaker and colleagues saw
rapid progress in traits such as growth, vigor, palatab-
ility to livestock, cold tolerance and insect resistance.
Interestingly, this is the agroforestry species that is
most widely planted throughout the tropics, and this
is presumed to be due both to availability of seed and
of improved varieties.
With the exception of Leucaena, there has been
little formal breeding of agroforestry trees. To date,
tree improvement in agroforestry has largely come
about through species and provenance screening trials
for sexually propagated species, and through clonal
174
selection for vegetatively propagated species. It is
worth contrasting this situation with the tree improve-
ment program of a single developed country such as
Sweden, which has more than 1500-plus trees and
3500 clones in seed orchards in 22 separate breeding
populations for a single species, Picea abies (Norway
spruce) (FAO Reforgen Database: www.fao.org).
In the absence of formal tree improvementin agro-
forestry, informal selections by farmers, mostly with
trees on their farms, dominate rural areas. Research-
ers are beginning to understand better the techniques
used and traits sought by farmers (e.g., Lovett and Haq
2000; Schreckenberg et al. 2002b). It is worth noting,
however, that the poor results from some farmer selec-
tions are due largely to a narrow founder populations
and inbreeding through propagation from a limited
number of parents. This observation is borne out by
the superiority of many wild populations that were
recollected and compared with exotic landraces (e.g.,
Gliricidia; Simons and Stewart 1994). With fruit trees
and some other trees, which are clonally propagated
the issue does not arise although the optimal number
of clones to use is a consideration.
Participatory domestication
In recent years international aid to developing coun-
tries has developed a strong focus on poverty reduc-
tion. In parallel with this, the World Agroforestry
Centre (formerly ICRAF) initiated its tree domest-
ication program in the mid-1990s with a new focus
on products with market potential from mainly in-
digenous species (Simons1996). With this came a
shift from on-station formal tree improvement towards
more active involvement of subsistence farmers in the
selection of priority species for domestication and the
implementation of the tree improvement process. In
many ecoregions in which ICRAF is active, farmers
selected indigenous fruit trees as their top five priorit-
ies. Consequently, over the last decade a strategy for
the domestication of indigenous trees producing high-
value products of traditional and cultural significance
has been developed (Tchoundjeu et al. 1998; Leakey
et al. 2003). This approach to improving the trees
planted by farmers has a number of advantages:
It has a clear poverty reduction focus, which has
been endorsed by a review on behalf of UK De-
partment for International Development (DFID)
(Poulton and Poole 2001). The income derived from
tree products (AFTPs) is often of great importance
to women and children, for example, to meet the
demand for school fees and new uniform.
It has immediate impact by going straight into im-
plementation at the village level, so avoiding delays
arising from constraints to the transfer of techno-
logy from the field station to the field that can be due
to technical, financial, dissemination and political
difficulties.
The approach being developed is focused on simple,
low-cost, appropriate technology yielding rapid im-
provements in planting stock quality based on se-
lection and multiplication of superior trees in ways
which create new plants, which also produce fruits
within a few years and at heights which are easily
harvested.
It builds on traditional and cultural uses of tree
products (AFTPs) of domestic and local commer-
cial importance, and meets local demand for tradi-
tional products.
It promotes food and nutritional security in ways
that local people understand, including promoting
the immune system, which is especially important
in populations suffering from AIDS.
It can promote local level processing and entre-
preneurism, hence employment and off-farm eco-
nomic development. These benefits can stimulate a
self-help approach to development and allows poor
people the opportunity to empower themselves.
It can be adapted to different labour demands,
market opportunities, land tenure systems, and is
appropriate to a wide range of environments.
It builds on the rights conferred on indigenous
knowledge and the use of indigenous species by the
Convention on Biological Diversity and is a model
for ‘best practice,’ in contrast to biopiracy.
It builds on the commonly adopted farmer-to-farmer
exchange of indigenous fruit tree germplasm as
practiced in west and central Africa, for example
Dacryodes edulis, which although native to south-
east Nigeria and southwest Cameroon, is now
found across much of the humid tropics of central
Africa (Cameroon, Congo, Central African Repub-
lic, Zaire, Gabon, etc.).
It builds on the practice of subsistence farmers to
plant, select and improve indigenous fruits (Leakey
et al. 2004), such as marula (Sclerocarya birrea)in
South Africa, where the yields of cultivated trees
are increased up to 12-fold and average fruit size
is 29 g, while trees in natural woodland are 21 g
(Shackleton et al. 2002).
175
The domestication of new local cash crops provides
the incentive for farmers to diversify their income
and the sustainability of their farming systems
(Leakey 2001a,b).
Against these advantages there are possibly dis-
advantages, such as reduced genetic diversity in the
wild population as it is replaced by a domesticated
population. However, the implementation of some
in situ or ex situ conservation (McNeely 2004) of
wild germplasm, together with the deliberate selec-
tion of relatively large numbers of unrelated cultivars
can minimize these risks. Indeed, the current strategy,
whereby each village develops its own set of cultivars,
should ensure that at a national/regionalscale the level
of intra-specific diversify remains acceptable for the
foreseeable future.
Concerns about genetic diversity and how to help
farmers to maximize their gains through plus-tree se-
lection for multiple traits have raised questions about
how farmers perceive variation. Consequently, quant-
itative studies of tree-to-tree variation in fruit and nut
traits have been implemented at the village level, and
it is clear that there is very considerable intra-specific
variation in each trait and that many of these traits
are unrelated (e.g., Irvingia gabonensis - Atangana
et al. 2001, 2002; Leakey et al. in press). Thus, the
current approach to selection of trees meeting various
market-oriented ideotypes ensures that cultivars are al-
most certainly highly variable in many other desirable
traits, such as resistance to pests and diseases. It is
also interesting that in terms of the level of variability
in the measured traits, the current semi-domesticated
on-farm populations are more variable than the wild
populations (Leakey et al. 2004) suggesting farmer
selections may have multiple population origins.
To maximize the economic, social and environ-
mental benefits from participatory domestication it
is crucial to develop post-harvest techniques for the
extension of shelf life of the raw products, and pro-
cessing technologies to add value to them. Without
this parallel preparation for increased commercialisa-
tion, domestication will not provide all the above-
listed benefits. The combination, however, has po-
tential applications that extend beyond subsistence
agriculture to agricultural diversification of farming
systems. In tropical North Queensland, Australia, for
example, this is linked, at least in part, to the develop-
ment of an Australian ‘bush tucker’ industry supplying
restaurants and supermarkets worldwide.
In his review of how agroforestry fits the Millen-
nium Development Goals, Garrity (2004) concludes
that agroforestry needs ‘a research and development
strategy to reduce dependency on primary agricultural
commodities, and to establish production of added-
value products based on raw agricultural materials
(with traditional and cultural values and locally recog-
nized importance and markets), with links to growing
and emerging markets.’ In agreement with much of the
above on agroforestry tree domestication, Garrity af-
firms that agricultural R&D institutions must develop
new skills in the domestication of indigenous species
and the processing/storage of their products, in market
analysis and market linkages. This would help focus
development on poverty in ways that are of interest
and importance to subsistence farmers.
Case studies
Two case studies are presented for agroforestry species
that are used primarily for timber, fruit and medicinal
products.
Prunus africana
Prunus africana (Rosaceae) – ‘pygeum’ – is an
afromontane forest species found only above 1000 m
altitude and confined to isolated populations form-
ing a wide but disjunct distribution (Cunningham and
Mbenkum 1993). The genus Prunus contains more
than 200 species (e.g., peach [Prunus persica]and
plum [Prunus domestica]) of which many have un-
dergone intensive domestication through selection and
breeding. Prunus africana is however the only spe-
cies native to Africa and is an important medicinal
tree (Hall et al. 2000). Currently, the commercial har-
vesting of the bark (approximately 4000 Mg of bark
per year) for commercial and domestic medicinal use
(treatment of Benign Prostatic Hyperplasia [BPH]) has
led to extinction of some populations and the listing of
the species on the CITES Appendix II. This is a list of
plants requiring protection through extraction permits
and monitoring of international trade, which currently
has an over-the-counter value for P. africana products
of $220 million per year (Cunningham et al. 1997).
The combination of the intense conservation in-
terest, the considerable commercial and human health
importance of the medicinal product, and the potential
of the species to be cultivated by small-scale farmers
has resulted in the development of a domestication
strategy (Leakey 1997; Simons et al. 1998) aimed at
the restoration of the resource through diverse agro-
forestry plantings. This strategy is expected to enhance
176
farmer livelihoods, meet future needs of the industry
and, to some extent, have positive ecological and
conservation benefits.
The objectives of domesticating P. africana are:
1) To conserve wild populations through reducing
pressure on the natural resource base by encour-
aging cultivation of trees by small-scale farmers.
Cultivated material also serves a useful circa situ
conservation function if attention is paid to genetic
diversity issues.
2) To locate unique and diverse natural populations
that warrant specific in situ conservation measures.
3) To identify productive genetic diversity to demon-
strate the growth potential of the species.
4) To quantify the genetic control of traits of eco-
nomic interest (timber volume, chemical profile,
bark yield) and determine appropriate selection
methods.
5) To undertake participatory domestication with
small-scale farmers to determine their preferences
and perspectives on cultivating and improving the
species.
6) To establish seed production stands and develop
appropriate management techniques to be able to
deliver sufficient propagules to farmers.
7) To improve propagation methods of the species to
encourage wider adoption.
8) To undertake marketing studies in order to better
monitor and predict demand and supply, and evalu-
ate prospects for green-labelling and the establish-
ment of premiums for small-scale producers.
9) To use P. africana as a case study for the domest-
ication of other medicinal and high-value trees.
The first step before developing a domestication
strategy for any species is to collate all available
information on the species including: botanic descrip-
tions, geographic distribution, ecology, forest invent-
ories, farmer surveys, harvesting techniques, trade
figures and conservation status. For P. africana,the
key information gaps identified were details on market
intelligence, growth data, reproductive ecology, pests
and diseases, genetic variation and propagation meth-
ods. These knowledge gaps have been the subject of
recent studies.
Market intelligence projections suggested that,
given the increase in the aging male population in
Europe and America and the increase in consumer
confidence in herbal remedies, demand could rise two-
to three-fold (to 8000 to 12000 Mg per annum). It
is clear that natural forests will not be able to meet
such demands and thus that cultivation is required.
This raises issues about how to achieve this cultiv-
ated resource, which are reflected by the two unlikely
extremes of a single plantation of 8000 hectares (at
4×4 m spacing) benefiting a very limited number
of producers, or many smallholders each producing a
few trees through agroforestry (one farmer growing 5
million trees or a million farmers each producing five
trees).
Studies of the few existing plantations of P. a f r i c -
ana in Cameroon and Kenya found that trees over 12
years of age produced acceptable yields and concen-
trations of active constituents, although yields of bark-
extract increased as trees aged further (Kimani 20021;
Cunningham et al. 2002). The highest bark-extract
yield (1.2%) was found in 55-year-old trees, although
trees of similar diameter class can have differences in
mean extract yield from 0.8% to 1.33%. In addition,
the major sterol component, B-sitosterol, varied signi-
ficantly between provenances (101 µg/g to 150 µg/g),
while individual tree yields varied from 50 µg/g to
191 µg/g). It is not known to what extent this vari-
ation is under genetic control. However, molecular
studies of neutral genetic variation have revealed that
differences between populations across the range ac-
count for 58% to 73% of total variation (Muchugi
20012)reflecting the disjunct nature of afromontane
populations. Elite trees of different provenances are
now being mixed in a seed orchard, with trees from
Kibale, Rwenzori and Bwindi populations in Rwanda.
This approach is comparable to industrialforestry with
combining populations in Breeding Seedling Orchards
(Barnes and Simons 1994).
Studies of the storage of P. africana seed have
found that it is recalcitrant to intermediate in its beha-
viour. Greatest germination (40% to 70%) was found
when purple coloured seeds were collected and de-
pulped. Extracted seeds could be stored at 4 Cfor
up to one year at 15% moisture content, although this
decreased viability by 50%. Surveys of seed price in
Kenya and Cameroon show it to be $8 to $25 per kg,
which at 3000 to 5000 seeds per kg, makes it relatively
expensive. The infrequent nature of fruiting, high price
or seed and recalcitrant seed behaviour indicate that
sourcing sufficient seedlings on a regular basis may be
problematic.
Vegetative-propagation studies for P. africana in
Kenya and Cameroon have found that juvenile tis-
sues root well (75% to 90%) as leafy cuttings (Nzilani
19993; Tchoundjeu et al. 2002), opening the way
for clonal approaches to producing medicinal extracts
with high yield, quality and uniformity. On-station tri-
177
als have been established in Muguga and Kakamega
(Kenya), Kabale (Uganda) and Buea (Cameroon) to
examine growth and survival, as well as family and
provenance variation. Species prioritization studies
with farmers in Cameroon, Uganda and Kenya have
confirmed the use and popularity of the species. On-
farm planting with Prunus has now taken place in
Cameroon, Kenya, Madagascar and Uganda, all with
unimproved material. By the mid 1990s these had
occurred on several thousand small-scale farms in
Cameroon (Cunningham et al. 2002), although to date
these immature plantings have not taken pressure off
the trees in natural forests.
It is foreseen that the on-farm cultivation of
P. africana would result in the following outcomes:
Trees grown on field boundaries have more spreading
crowns than in closely spaced plantations, but are a
good source of bark and timber.
Before felling for timber, nondestructive bark pan-
elling can be undertaken at 15, 23 and 31 years
– providing 15, 25 and 60 kg of bark per tree,
respectively.
A tree could conceivably be felled for timber at 40
years of age, when it would yield approximately
200 kg of bark.
This equates to a production of 7.5 kg of bark per
tree per year over a 40-year period.
For a 3000 Mg market, 400 000 such trees will be
needed.
For a 10 000 Mg market, 1.3 million trees will be
needed.
Dacryodes edulis
The domestication of Dacryodes edulis – Safou or
African plum – has been the developingmodel for Par-
ticipatory Domestication approaches in Cameroon and
Nigeria described above (see papers in Schreckenberg
et al. 2002a), since its identification as the top priority
species for agroforestry in western and central Africa.
It is widely grown in mixed farming systems across
many countries of Central Africa (28% to 57% of all
fruit trees), especially as the shade tree for cacao or
coffee in the forest-savanna transition zone, as well
as a middle-stratum in cacao farms under secondary
humid forest and as a common constituent of homeg-
ardens. Mean numbers of trees per farm range from
20 to 200 in some villages in Cameroon (Schrecken-
berg et al. 2002b), with tree density being greatest
in farms under 2 ha. In 1997, the trade of Safou in
Cameroon alone was worth $7.5 million, excluding
domestic consumption. Of this trade, $2.5 million is
in exports (Awono et al. 2002). The fruits are typically
roasted and eaten as a nutritious staple; it is rich in
fat (64%), protein (24%) and carbohydrate (9%); and
there is the potential for vegetable oil extraction on a
commercial scale.
There is considerable farmer-to-farmer exchange
of germplasm of this species, which almost certainly
explains its common occurrence in farmland even out-
side its natural range, regardless of social features such
as the wealth of the farmers, prevailing land tenure
regime, labour availability, and level of education.
The multi-institutional and multi-disciplinary domest-
ication program is built on earlier tree improvement
studies examining reproductive biology, provenance
variation, etc. initiated by the Institut de la Recher-
che Agricole pour le Dévéloppement (IRAD) (Kengue
1998; Kengue and Singa 1998). Now it is being fo-
cussed at the village level on the development of
cultivars from trees with superior fruit size, color and
taste. Vegetative propagation techniques, especially
marcotting, have been used to capture the phenotype
of selected trees and so to produce cultivars. To in-
crease the multiplication rate, initial problems with
the rooting of leafy stem cuttings have been over-
come using simple, low-tech propagators established
in a central nursery and replicated in all pilot villages
(Leakey et al. 1990). With the help of NGOs, the
villagers have been trained in nursery and vegetative
propagation skills and become the nursery managers
and the owners of the germplasm developed from their
local population.
Some 10-fold variation in mean fruit mass between
different trees, and additional variation in other com-
mercially important traits, indicates considerable op-
portunity to increase the size and quality of fruits for
market. To this is being added a better understanding
of consumer preference and assessment of the ge-
netic variation in sensory traits (taste, oiliness, acidity,
smell, etc.), and studies to relate these to other visual
characteristics are underway. Selection criteria based
on the identification of market-oriented ideotypes have
been identified (Leakey et al. 2002; Anegbeh et al. in
press) so that the improved prices of desirable fruit
types currently only recognized in retail urban mar-
kets can be acquired by the producer dealing with
traders at the farm gate. Currently the diversity in fruit
size and quality from the virtually wild trees on most
farms, each phenotypically different from other trees,
precludes wholesale buyers from recognizing super-
ior fruits. Hopefully, however, when a vehicle can
178
be loaded with the uniform fruits of recognized cul-
tivars, farmers will be financially rewarded for their
efforts. In Cameroon, women have indicated that the
coincidence of schooling expenditures with income
flows from the sale of fruits is one of the attributes
of D. edulis that they appreciate (Schreckenberg et al.
2002b).
Currently, Safou fruits are perishable and difficult
to store for more than a few days. However, studies
are in progress to improve shelf life by various forms
of processing and value-adding.Once this is achieved,
it is anticipated that the demand will increase and the
fruits, or fruit products, will become available outside
the current four-to-five-month production season. In
parallel with these developments are studies to under-
stand more about the potential for the production of
different oils for the food industry, involving the rela-
tionships between oil quality and other chemical and
morphological traits. Safou fruits are already traded
on a small scale into Europe and America; it is hoped
that the combination of targeted genetic selection and
processing will open up market opportunities, which
can further benefit subsistence farmers. Much work
remains to be done to ensure that this is achieved,
with particular recognition that the intellectual prop-
erty of the farmers developing the cultivars needs to
be assured.
Recommendations: future developments
From the issues discussed in this paper, there is evid-
ently much work to be done to build on the work of the
last decade. There are very large numbers of species
in all ecoregions, which potentially could be domest-
icated to produce marketable AFTPs and environ-
mental services. The extension of the above mentioned
strategies, principles and techniques to even a small
proportion of these species represents an enormous
challenge to countries and to development agencies
with limited resources. Probably the biggest constraint
to achieving this on the scale required is the serious
lack of people in NGOs and National Agricultural Re-
search Systems (NARS) with adequate knowledge of
vegetative propagation techniques for trees. There is
also a need for better methods of propagating mature
trees (Leakey in press). Resolving the technical and
implementation issues surrounding the expansion of
this ‘grass-roots’ revolution will be enormous, with
strategies on issues such as how to avoid a loss of
intra-specific genetic diversity needing to be resolved,
especially when recognising that crop domestication is
an on-going iterative process.
The problems of widespread implementation of
the domestication of agroforestry trees will be ex-
acerbated by the fact that the philosophy to diversify
farming systems and economies in the ways described
here runs counter to the philosophy promulgated by
many agencies that biotechnology is the solution to the
issues of poverty, malnutrition and rural development.
Nevertheless, there is a growing body of evidence that
supports the agroforestry solution to many of these
problems, and the evident congruence between agro-
forestry outputs and Millennium Development Goals
offers hope for the future (Garrity 2004). Agroforestry
centred on indigenous trees is very compatible with
the aims of the Ecoagriculture initiative ratified at the
World Summit on Sustainable Development in Johan-
nesburg in 2002 (McNeely and Scherr 2003). In this
regard, tree domestication provides a powerful incent-
ive for subsistence farmers to diversify their farms
with indigenous trees that provide economic returns
and environmental services, including biodiversity
conservation (see also McNeely 2004).
In addition, the future success of AFTP domestica-
tion and commercialization will depend on the benefits
remaining with the small-scale farmers and their local
industries and markets. (Clement et al. 2004) This
will inevitably depend on finding ways to satisfact-
orily protect the intellectual property rights (IPR) of
the farmers and communities investing in the pro-
cess. Currently it is unclear how individual farmers
and communities in economically and socially disad-
vantaged countries can avail themselves of the ‘rights’
conferred by the Convention on Biological Diversity.
In this connection, the attempts of the African Union
to develop a model law for the protection of the rights
of poor farmers is encouraging.
The ‘chicken-and-egg’ linkages between domest-
ication and commercialization will be difficult to re-
solve, making it crucial that agroforesters find ways
to work closely with commercial and industrial part-
ners so that the products match the needs of both
the farmers, the processing industries and the con-
sumers. It may not be a beneficial situation for every-
one and clear understanding of the winners and losers
of greater cultivation and commercialisation will be
needed.
Finally, however, the strength of the approach lies
in its ability to empower the millions of farmers des-
perate to improve their lot in the world. What they
need most is information about what is possible and
179
the simple skills needed to do the job. The public in
the developed world can help by buying the newly im-
proved products, and by demanding that policy makers
recognise the importance of simultaneously resolv-
ing the poverty and environmental crises facing the
developing world.
End Notes
1. Kimani P.G. 2002. Population variation in yield and compos-
ition in bark chemical extracts of Prunus africana, and its
potential for domestication. M. Phil Thesis, Moi University,
Kenya, 73 pp.
2. Muchugi A.M. 2001. Genetic variation in the threatened medi-
cinal tree Prunus africana in Kenya and Cameroon: implica-
tions for the genetic management of the species. M. Sc. thesis,
Kenyatta University, 90 pp.
3. Nzilani N.J. 1999. The status of Prunus africana in Kakamega
Forest and the prospects for its vegetative propagation. M. Phil.
thesis, Moi University, Kenya, 78 pp.
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... It is estimated that up to half the harvest is lost during the fruiting season due to soft rot , which means it is difficult for farmers to store and transport the fruit and often forces them to sell to traders instead of taking the harvest to market themselves . Efforts are being made to increase the durability of the fruit through processing and genetic selection, which could eventually help in transporting it over longer distances and enable farmers to sell over a longer period than the current four months of the harvesting season (Simons and Leakey 2004). ...
... In Dacryodes edulis is considered the most important tree species in many homegardens and agroforestry systems, accounting for 28-57% of all trees in agroforestry systems in Central Africa (Simons and Leakey 2004). Farms in Cameroon typically contain 20-200 D. edulis trees (Simons and Leakey 2004). ...
... In Dacryodes edulis is considered the most important tree species in many homegardens and agroforestry systems, accounting for 28-57% of all trees in agroforestry systems in Central Africa (Simons and Leakey 2004). Farms in Cameroon typically contain 20-200 D. edulis trees (Simons and Leakey 2004). In Central Africa, D. edulis is one of the most common edible intercrops in cocoa plantations, along with Citrus sinensis, Citrus reticula, Mangifera indica and Persea americana (Sonwa et al. 2014). ...
... Domestication and cultivation of species is a very convenient option to relieve the pressure on valuable and threatened wild populations and species, contributing both to conservation and overall socioeconomic developmental objectives. e domestication of locally marketed indigenous fruit trees contributes to the diversification of production and rural incomes and enhancement of the livelihoods of rural communities [1,21]. e increased planting and management of the indigenous and wild edible fruit trees also help to restore degraded ecosystems and conserve their declining diversity [1]. is involves the selection or prioritization, improvement of productivity, and developing marketing strategies of the most highly valued wild/indigenous fruit trees. ...
... East African regions have many potentials and priority indigenous woody species for domestication, particularly in the semiarid lowlands [17,42]. Large numbers of tree species exist in all ecoregions, which potentially could be domesticated to produce marketable products [21]. An estimated 8% of the total 7000 higher plants in Ethiopia are edible, including woody fruit-bearing species [15,47]. ...
... Prioritization is necessary to draw full attention to the more promising species. e first step in the overall domestication and profitable exploitation of a wild edible species is identifying the most promising species for domestication in a region [21]. e choice of which trees to domesticate should follow a priority setting that identifies the most highly valued species [22]. ...
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Wild edible fruit species are commonly consumed and utilized in different parts of Ethiopia for staple food, filling seasonal food shortages, emergency food during a famine, and household income generation. There is a pressing need for domestication and improvement of some wild edible fruits for increased production, diversifying income for small-scale farmers, and conservation of the diminishing wild edible fruit resources. A total of 37 widely utilized and marketed wild edible fruit species falling into 23 families were recognized as of used in different parts of the country. Of which, 26 species are identified as available in local markets in different parts of the country. Ziziphus spina-christi, Syzygium guineense, Balanites aegyptiaca, and other nine species were identified as a priority wild edible fruit species from available information based on utilization extent, preference ranking by farmers, product marketability, and conservation needs for the species. There exists a lack of scientifically planned genetic variation evaluation, superior variety selection, genetic improvement, and seedling production initiatives for indigenous wild edible fruit species in Ethiopia. All of the 37 widely utilized and marketed wild fruit species have not developed to their full potential in terms of quality, production scale, and market in the country. Identifying and selecting priority species, strengthening botanical information, germplasm collection and improvement, production and processing technologies, increasing the supply of improved planting materials, and promoting on-farm cultivation of wild edible fruit-based agroforestry systems were identified as key future strategies for domestication and wider cultivation of wild edible fruit species.
... Leaching and surface runoff from the forest patches might feed adjacent grasslands and farmlands with nutrients. While both exotic and indigenous trees have the potential to provide nitrogen replenishment in degraded tropical systems, domestication of indigenous tree species has been considered in the past two decades as an alternative to subsistence commercial plantations and slash-and-burn operations associated with the destruction of tropical and sub-tropical indigenous forests (Sanchez et al., 1997;Leakey and Simons, 1998;Simons and Leakey, 2004). Although the commercial value of domesticated indigenous trees would not meet those of e.g. ...
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... Many small and subsistence farmers have tried to domesticate trees of high quality germplasm to ensure improved productivity while maintaining crop diversity. The approach for choosing a particular species may also be confirming their ecological traits, management choices and to meet the target environment [9]. The trees, in particular in HGs are traditional natural solution to climate change mitigation [10,11]. ...
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... Whilst it is unlikely that farmers would actually consider age as one of the factors during the tree selection process, the number of pods per tree seems a more reasonable criterion for selection and in this regard, only 6 of the surveyed trees were in the range given by Roy et al. (2016), whilst most trees (20) had higher to much higher pod yields. Beside the general tendency of trees to produce a larger quantity of seeds and better quality seeds at a mid-age period (Espahbodi et al. 2007), they also have the chronological and physiological age advantage of vigour and early bearing when propagated vegetatively (Leakey 2014) Individual tree selection is the first important step in any tree domestication program of IFT species (Simons and Leakey 2004), be it an institution-driven program or a farmerdriven effort. In either case, individual tree characterisation of fruit parameters is an exercise undertaken at many instances to ascertain the amount of variation captured for future trait improvement (see, for instance, Tsobeng et al. 2020). ...
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Stem cuttings of five tree species from dry and semi-arid woodlands and seven species from moist tropical forests have been easily rooted in improved low-technology, high humidity polythene propagators in Kenya, Cameroon, Costa Rica and Britain. These propagators, which are cheap to construct, are very effective and have no essential requirements for either piped water or an electricity supply. Experiments have tested different rooting media, auxin applications and compared mist versus non-mist propagation. -from Authors
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A win:win landuse strategy has to provide both economic and environmental benefits, ideally with enhanced livelihoods for the poor and the provision of commodities for the international market. This paper reviews recent developments in agroforestry and some case studies from SE Asia and Latin America, where income-generating non-timber forest products are being produced by subsistence farmers within either enriched forest fallows (agroforests) or other forms of multistrata agroforestry. It then examines the opportunities for similarly producing non-timber forest products in the four main regions of Africa (Humid lowland forests of West and Central Africa, the East African Highlands, and the Miombo woodlands of southern Africa and the Sahel), as well as opportunities to domesticate the priority tree species for income generation.