The role of tree domestication in agroforestry

292 Pages·2008·20.63 MB·English

á
-
Institute of
N
Terrestrial
W.7 Ecology
Edinburgh Centre
for Tropical Forests
IUFRO
Tropical trees:
the potential for domestication
and the rebuilding of forest
resources
ITE symposium no. 29
ECTF symposium no. 1
The proceedings of a Conference organised
by the Edinburgh Centre for Tropical Forests,
held at Heriot-Watt University Edinburgh,
on 23-28 August 1992,
as part of the 1UFRO Centennial Year (1892-1992)
Edited by
R R B Leakey and A C Newton
London: HMSO
@ Crown Copyright 1994
Applications for reproduction should be made to HMSO
ISBN 0 11 701562 8
The Institute of Terrestrial Ecology (ITE) is a component research organisation within the Natural Environment
Research Council. The Institute is part of the Terrestrial and Freshwater Sciences Directorate, and was established
in 1973 by the merger of the research stations of the Naiure Conservancy with the Institute of Tree Biology It has
been at the forefront of ecological research ever since. The six research stations of the Institute provide a ready
access to sites and to environmental and ecological problems in any part of Britain. In addition to the broad
environmental knowledge and experience expected of the modern ecologist, each station has a range of special
expertise and facilities. Thus, the Institute is able to provide unparallelled opportunities for long-term,
multidisciplinary studies of complex environmental and ecological problems.
ITE undertakes specialist ecological research on subjects ranging from micro-organisms to trees and mammals,
from coastal habitats to uplands, from derelict land to air pollution. Understanding the ecology of different species
of natural and man-made communities plays an increasingly important role in areas such as monitoring ecological
aspects of agriculture, improving productivity in forestry controlling pests, managing and conserving wildlife,
assessing the causes and effects of pollution, and rehabilitating disturbed sites.
The Institute's research is financed by the UK Government through the science budget, and by private and public
sector customers who commission or sponsor specific research programmes. ITE's expertise is also widely used
by international organisations in overseas collaborative projects.
The results of ITE research are available to those responsible for the protection, management and wise use of our
natural resources, being published in a wide range of scientific journals, and in an ITE series of publications. The
Annual Report contains more general information.
R R B Lenkey* and A C Newton
Institute of Terrestrial Ecology
Bush Estate
Penicuik
Midlothian EH26 OQB
Scotland, UK
Tel: [phone]
*In November 1993, Dr Leakey was seconded to the International Centre for Research
on Agroforestry as Director of Research
His current address is:
ICRAF, United Nations Avenue, Gigiri, PO Box 30677, Nairobi, Kenya
Contents
Page nos
Preface
Domestication of 'Cinderella' species as R R B Leakey & A C Newton
the start of a woody-plant revolution 3
The resource of useful tree species: identification of priorities
for domestication
Amazonian tree diversity and the G T Prance
potential for supply of non-timber
forest products 7
Designing commercially promising J R Palmer
tropical timber species 16
Timber trees: architecture and ecology R A A Oldeman &
A H M Sieben-Binnekamp 25
Fruit trees: diversity and conservation J C Okafor & A Lamb
strategies 34
Trees for drugs and other extractives: P G Waterman
future propects 42
Techniques to domesticate trees
In vitro systems for the conservation F Engelmann
and utilisation of germplasm 49
Capture of genetic resources by in vitro S S Khuspe, R S Nadgauda,
culture: field evaluation and S M Jagtap, C K John &
precocious flowering A F Mascarenhas 53
Capture of genetic resources by P B Tompsett
collection and storage of seed: a
physiological approach 61
Capture of genetic variation by R R B Leakey A C Newton &
vegetative propagation: processes J McP Dick
determining success 72
Selection and breeding to conserve and R D Barnes & A J Simons
utilise tropical tree germplasm 84
Strategic concepts in the domestication A J Simons, D J MacQueen &
of non-industrial trees J L Stewart 91
Clonal development and deployment: G S Foster & F L G Bertolucci
strategies to enhance gain while
minimising risk 103
Regeneration of new forest resources
Indigenous trees in West African forest G J Lawson
plantations: the need for domestication
by clonal techniques 112
The role of tree domestication in F L Sinclair, I Verinumbe &
agroforestry J B Hall 124
Use and potential of domesticated trees E C M Fernandes, D P Garrity
for soil improvement L T Szott & C A Palm 137
Matching trees to their light environments F E Fasehun & J Grace 148
Harnessing symbiotic associations: F Lapeyrie & P H6gberg
ectomycorrhizas 158
Harnessing symbiotic associations: P A Mason & J Wilson
vesicular—arbuscular mycorrhizas 165
Harnessing symbiotic associations: the J I Sprent
potentials of nitrogen-fixing trees 176
Case studies
Capturing and managing the genetic P Felker
variation in Prosopis spp. for
economically useful characters 183
Domestication of lesser-known tropical T H Booth & J W Rirnbull
tree species: the Australian experience 189
Domestication of lesser-known species J L Brewbaker & C T Sorensson
of the genus Leucaena 195
Domestication of Sesbania sesban for F Owino, P A Oduol & F Esegu
agroforestry systems in eastern and
southern Africa 205
Domestication of trees in semi-arid East P B Milimo, J McP Dick &
Africa: the current situation R C Munro 210
Domestication potential of indigenous J A Maghembe, F Kwesiga,
fruit trees of the miombo woodlands M Ngulube, H Prins &
of southern Africa F M Malaya 220
Amazonian fruits and nuts: potential for C R Clement & H Villachica
domestication in various
agroecosystems 230
Genetic improvement of West African D 0 Ladipo, S P K Britwum,
tree species: past and present Z Tchoundjeu, 0 Oni &
R R B Leakey 239
Genetic improvement of trees in Central J F Mesén, D H Boshier &
America, with particular reference to J P Cornelius 249
Costa Rica
Domestication of mahoganies A C Newton, R R B Leakey
W Powell, K Chalmers, R Waugh,
Z Tchoundjeu, P J Mathias,
P G Alderson, J F Mesén,
P Baker & S Ramnarine 256
Production of clipterocarp planting stock W T M Smits, A C de Fraiture
by cuttings in Indonesia & I Yasman 267
Poster paper titles 273
List of Conference participants 275
Preface
Domestication of 'Cinderella' species as the start
of a woody-plant revolution
R R B Leakey & A C Newton
Institute of Terrestrial Ecology*, Bush Estate, Penicuik, Midlothian EH26 OQB, UK
*A component of the Edinburgh Centre for Tropical Forests
We are all aware that the pressures on tropical but would still like supplies of traditional food,
ecosystems are increasing daily: that human and medicines and other natural products. These
livestock populations are rising, and that the traditionally important woody plants are virtually
stock of productive land is fmite and dwindling undomesticated, ignored by the 'green revolution',
as a result of misuse. Deforestation is reducing yet probably have great genetic diversity They
species diversity and eroding the genetic base of also play a key role in the biological, chemical,
many tropical tree species, including those used physical and hydrological cycles of the soil and
traditionally by local people for products that the atmosphere, protecting soils from damage
fulfil many of their domestic needs. Forest and acting as a buffer against environmental
degradation is also having negative impacts on change. These same plants are the ones that are
soil fertility and is modifying climate by cut down indiscriminately to relinquish a few
local/regional influences on the albedo and valuable logs per hectare, to clear land for
hydrological cycle, as well as by the emission of 'development' projects or to provide a
trace gases to the atmosphere. subsistence living for a year or two. These
overlooked and often highly desirable trees are
Together, the above consequences of
the 'Cinderella' species of our forests.
deforestation combine to reduce the area of
productive land needed by growing human 'Cinderella' species are often ignored by
populations, and to increase poverty and the agriculturalists of the developed world in favour
incidence and severity of famine. At present, the of a handful of exotic species which have been
demand for farm land is met by opening up domesticated and grown artificially on a large
new areas of forest to agriculture. It is therefore scale. The choice is often made without much
important to increase the resource of trees in thought for the environment, and, perhaps, with
deforested areas, so as to meet the traditional thought only for relatively short-term economic
needs of local people, including the urban gains. The same scenario has occurred in
populations. Somehow a way has to be found to forestry While planting and domesticating a few
make the land more productive and to exotic fast-growing trees for pulp and paper, the
rehabilitate degraded areas in a way which will majority of the hardwood species forming the
diversify production, promote genetic basis of the timber trade have not, for a variety
conservation, enhance the development of of reasons, contributed significantly to
sustainable land use and contribute to domestic, reafforestation programmes. Surprisingly therefore,
regional and international trade. the absence of even beautiful and commercially
important timber trees such as mahogany from
Great progress was made with food crops in the
man-made forests allows them to be classed as
l960-80s, as a result of the 'green revolution',
'Cinderella' species. The resources of these
but now there is a need to diversify into new
'Cinderella' tree species can be tapped by the
crops, many of which could be tree crops. This
process of 'domestication', which has been
diversification is desirable ecologically and
applied so successfully to agricultural and
economically to reduce the dependence on
horticultural crops.
commodity crops with falling product prices. In
addition, without genetic engineering, further One of the objectives of this Conference is to
large increases in the yield of the current narrow raise the profile of the 'Cinderella' species, and,
range of crop species are unlikely particularly to draw attention to a growing effort
Throughout the tropics there are numerous to domesticate a much wider array of tree
perennial woody species that have provided species and introduce them into agricultural and
indigenous peoples with many of their needs for forestry systems. The domestication of
millennia. Many of these people have now left traditionally utilised 'Cinderella' species providing
the land for the concrete jungles of urban life, fuelwood, poles, timber, fruits, gums, nuts, resins,
3
fibre, pharmaceutical products, etc, can now be for sale in local, regional and even international
rapidly achieved by applying some of the market-places. It has also been realised that
techniques described in these Proceedings. This there is a need to improve management systems
approach has the added environmental benefit of if new cultivars are to be as productive as they
diversifying the species grown on farm land and could be, and if they are to be used to
in forest plantations. In addition, domesticating rehabilitate deforested land. Options include
these species will go some way towards systems which rehabilitate the environment on a
reducing economic dependence on a few local scale, by improving soil structure and
'commodity' species. In this way a start is being fertility Other systems may have more wide-scale
made to initiate a 'woody-plant revolution', which effects, such as beneficial impacts on the
could provide some cheer in the otherwise regional hydrology or global climate, by the
gloomy outlook for tropical forests. Opportunities creation of complex canopies which mimic
are currently being lost because of a lack of natural forests.
awareness of the potential to domesticate forest
There is also a growing realisation that the
tree species for the production of timber and domestication of these 'Cinderella' trees involves
non-timber products.
protecting their genetic resources and growing
What are the issues that have to be resolved to them wisely and efficiently to protect the
trigger this new revolution? From the viewpoint environment. Perhaps a 'woody-plant revolution' of
of a fanner, there are: this sort could contribute significantly to the
(cid:127) the political and social issues, such as how to rehabilitation of our planet and the feeding of its
acquire the right to own and protect a piece population. Hopefully the Proceedings of this
of land and the trees on it, and the need for Conference will inspire fairy godmothers,
incentives to plant trees; particularly policy-makers and donors, to
mobilise their glass carriages and get Cinderella
(cid:127) the economic issues, such as what is the to the ball.
value of these trees in terms of their wood,
other products and environmental services; Dedication
(cid:127) the biological issues, such as how to grow These Proceedings are dedicated to Douglas G
the trees wanted by farmers; how they can B Leakey who as a forester in Kenya all his
be made more desirable and productive, to career tried to encourage the planting of trees
the extent of satisfying the farmers' needs for environmental protection. It was this
and even providing a surplus which could awareness of the importance of trees that led
be sold to urban populations. him to write a paper in 1948 for a conference in
This Conference is about solving the biological the Belgian Congo, which subsequently inspired
issues concerned with the provision of timber, Professor Anthony Young of the International
food and other domestic necessities. However, Centre for Research in Agroforestry to commend
there are also direct economic and social him as one of the early advocates of agroforestry
benefits, such as improving community welfare (See ICRAF Newsletter (October 1986), 18, 5.)
through the market-place. To plant and grow
trees on a scale necessary to have any impact Domestication: a definition
on either the environmental or social The concept of a domesticated species is
consequences of deforestation, it is essential that familiar to most people in terms of farm animals
farmers, communities and companies see and household pets, but is not so common in
financial and other incentives accruing from tree plants. However, it is well laiown that modern
planting. The incentive of greater profitability is grain cultivars have been bred over generations
proposed as a powerful means of promoting the - from wild grasses, and that our gardens and
planting and growth of tree species. Genetic orchards are stocked with woody plants that have
improvements in yield and quality should similarly been subjected to selection and
increase the value of the products of a tree crop, breeding. Foresters have been slow to see the
while increased growth rates in timber trees will need to domesticate their crops. Until relatively
allow a shortening of the rotation, and hence a recently foresters have collected seeds from the'
more rapid return on invested capital. It should wild and used them without selection. The use of
not be at the expense, however, of the provenance selection, an early stage in the
environmental benefits of tree planting. domestication process, gained international
There has been a recent awakening to these importance in the 1960s, although techniques
biological issues, and significant progress has such as clonal selection have been used for
been made in the past '10-15 years. It has been centuries in a limited number of species - Salix,
realised that it is possible to capture the genetic Populus, Cryptomeria japonica, etc.
variation inherent in tropical tree populations, and The following are defmitions which help to
that this can be used to domesticate trees explain the processes which are involved in the
rapidly for timber as well as non-timber products domestication of a plant species.
4
(cid:127) To domesticate is to naturalise; make fond of regeneration and sustainable cultivation of the
home; bring under human control, tame; species in managed ecosystems (Figure 1). In
civilise (Concise Oxford Dictionary) the papers presented, it is clear that the starting
point can vary considerably depending on the
(cid:127) Domestication is closely linked to the idea of
approach taken, which in turn seems to depend
selection, of fitness for purpose, of pushing
on whether the domesticator is a peasant farmer
nature into a higher gear and in a particular
or a research scientist. Many of the species
direction (Palmer, pp16-24)
described can, thus, at best be described as
(cid:127) Domestication is a two-stage process in semi-domesticates.
plants: the bringing into cultivation of wild
In forestry the term 'domestication' has mostly
plants or exposing them to some form of
been applied to the genetic improvement of
management, and subjecting these to
trees for industrial plantations, but one message
differential production or selection (Janick et
from the Conference is that the domestication
al. 1982)
process in trees also has a strong social
(cid:127) Domestication is human-induced change in involvement, seen clearly from the examples of
the genetics of a plant to conform to human non-timber species. The need to develop this
desires and agroecosystems, culminating in social aspect has recently been recognised in
the plant's loss of its ability to survive in the strategic plan for the new Centre for
natural ecosystems (Harlan 1975) International Forestry Research (CIFOR) prepared
(cid:127) The four elements of the domestication by the Australian Centre for International
process in forest trees (Libby 1973): Agricultural Research. CIFOR is the newest
institute of the Consultative Group for
— the original genetic variability
International Agricultural Research.
— selection of the desired trees or genes
— a packaging of those genes in the plants
to be used References
— converting those gene packages into the Harlan, J.R. 1975. Crops and man. Madison, Wisconsin:
American Society of Agronomy/Crop Science Society of
growing trees which are harvested as a
America.
renewable resource.
janick, J., Schery, R.W, Woods, F.W. & Ruttan, V.W.
(cid:127) There are several stages to the domestication 1982. Plant science. San Fi-ancisco, California: Freeman.
of crops (described by Clement & Villachica,
Libby, W.J. 1973. Domestication strategies for forest trees.
pp230-238):
Canadian Journal of Forest Research, 3, 265-276.
— managed species
— semi-domesticates
Sponsors
— full domesticates
Aracruz International Ltd
At the Conference, the full 'domestication' of a
Australian Centre for International Agricultural
tree species was taken to encompass the
Research (ACIAR)
identification and characterisation of its
gerrnplasm resources; the capture, selection and Centre Technique de Co-operation Agricole et
management of genetic resources; and the Rurale (CTA)
DOMESTICATIONO F TROPICAL TREES
Socio-economaipcpraisal Developmento f techniques: Soil amelioration
Species selection (cid:127) capture by seed Silviculture
(cid:127) capture by vegetativep ropagation Agroforestry
4. Harnessings ymbiotic associations
Applicationo techniques:
germplasmc onservationa nd utilisation
(cid:127) selection
(cid:127) breeding
Resourcei dentification Capture,s e ection and Regenerationa nd sustainable
and characterisation management managemento f forest resources
of genetic resources
Figure I. Stages involved in the domestication of tropical trees
5
Commission of European Communities DG XI-B4 given to Mrs Carol Morris in the Conference
Commonwealth Science Council (CSC) Secretariat for all her hard work, Ms Lynn Davy
for proof reading and editorial assistance, and
Edinburgh Centre for Tropical Forests (ECU-)
Mrs Penny Ward for producing the fmal script.
International Union of Forestry Research We are grateful to colleagues who acted as
Organizations (RJFRO) referees of the manuscripts. Mr Bob Munro and
Shell International Petroleum Ltd Dr Alan Longman are also thanked for their part
in ensuring the smooth running of the meeting,
United Nations Educational, Scientific and Cultural
especially the Poster Session. Finally we
Organisation (UNESCO)
acknowledge the presenters of poster papers for
United Nations Environment Programme (UNEP)
their contributions to the information exchange at
the Conference, and sincerely thank all the
Acknowledgements authors for preparing their manuscripts on
We wish to thank our sponsors for their fmancial schedule, and for their tolerance during the
support, without which the Conference could not editing phase. This has allowed the Proceedings
have taken place. These funds partially to materialise without more delay than was
supported the participation of the invited inevitable as a result of our own overseas travel
speakers. Our thanks are also due to IUFRO and commitments.
ECTF for their support and assistance in
organising the meeting, the Conference
Organising Committee and staff of the Heriot
Watt Conference Centre. Particular thanks are June 1993
6