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Appendix D - Matching trees to technologies

The following indicative summaries and case-specific examples of ideotype specifications are presented for illustrative purposes only and should not be used as recipes or substitutes for diligent site-specific design work. Since this body of material reflects work in progress to systematize and develop a multidisciplinary perspective on tree and technology specifications, no attempt has been made to impose a premature standardization on the specifications given here. They are presented here in order to illustrate the range of considerations that enter into the derivation tree specifications for a particular application and have been recorded with a minimum of editorial modification in order to convey a feeling for the nature of the exercise.

The sample ideotype specifications presented here come from the reports of diagnostic and design exercises undertaken by ICRAF in collaboration with various national and international research partners during the planning phase of agroforestry research projects in a wide range of environments. The specifications represent an idealized conception of the kind of tree that would best suit the needs of the technology design concept developed by the D&D team.

It should be emphasized that these specifications are intended for use in

agroforestry research projects which are mandated to explore and develop promising agroforestry technologies. Although the basic relevance of the suggested technologies is established by the D&D process, the technical efficacy of some of the newer agroforestry technologies is still hypothetical. Just as there is no prior guarantee that the original design concept will work without modification in the intended environment, there is also no guarantee that the ideal tree exists. The tree specifications are used to guide the researchers in screening a wide range of trees for the desired attributes. This leads into tree management trials and, eventually, into trials of prototype technology designs with the intended land users. The astute reader will note the unevenness in the treatment of the specifications for different technologies. Obviously, the writing of tree specifications, like other design skills, is an art. As more is learned from the research which is now underway about agroforestry design principles and about the attributes of trees in the context of these new technologies, no doubt the standard of specification writing will also improve.

In accordance with the third principle of our selection strategy, all specifications should be regarded as hypothetical until validated by experience. If a given set of initial specifications proves too ambitious or optimistic, it is an error that will be corrected in the course of the search and screening process. Perhaps it is better to err on the side of optimism during the R&D phase of a tree growing technology and on the side of caution in the active dissemination phase.

The following key to the listing of tree specifications by technology in Table 25 classifies tree planting practices by arrangement of the tree/shrub and other components:





Table 25. Indicative tree specifications for selected agroforestry technologies based on results from a sample of diagnostic and design case studies.


(Synonym: dispersed trees in cropland, agrosilvicultural systems )

For supplementary production with minimal yield reduction, or net yield increase, of associated crops

General specifications

climatically suitable edaphically suitable vigorous growth

pest & disease resistance

ease of establishment (especially if proposed as low labour alternative to hedgerow intercropping)

direct seeding vegetative propagation

High yield and quality of desired product

For timber:

vigorous vegetative growth straight stems wood strength wood quality

For poles:

vigorous vegetative growth straight stems coppiceable

For fruit:

For industrial processing:

For fodder:

For cash:

Comuatibility with associated crops

Non-competitive with crops

deep rooting (minimal lateral spread) light canopy or

leafless during cropping season (e.g. A. albida ) fast-growing with high canopy self-pruning desirable (to reduce labour)

Soil benefits

N-fixing or other nutrient cycling ability high leafy biomass production

Microclimatic benefits

fire resistant tolerant of browsing

tolerant of periodic waterlogging (dimba) tolerant of drought stress requiring few purchased inputs

Source: Summarized from ICRAF t 1 (1982), ICRAF et al (1984), ICRAF and ICAR (1984), ICRAF and ICAR (1986), Minae and Akyeampong (1988), Djimde and Hoekstra (1988), Kwesiga and Kamau (1988), Djimde and Rainsree (1989).

2. DISPERSED TREES IN GRAZING LAND (Synonym: silvopastoral systems)

To increase supply of wood products &fodder (grass as well as tree leaves)

For all species

climatically suitable

edaphically suitable (pay attention to shallowness of soils in steep grazing land)

N-fixation desirable

vigorous growth compatibility with grasses For timberfpoles straight stems coppiceable (poles) browse resistant light canopy

leaves/pods palatable & nutritious pollardable

Source: Djimde and Hoekstra (1988)

For sylvopastoral systems combining tree products (timber, fruits, fodder, etc.) with grazing

provide some shade for animals fodder production in dry season Source: ICRAF and ICAR (1986)

For all species (reeardless of role) climatically & edaphically suitable deep rooting

vigorous growth nutrient rich litter

quick growth in shaded environment straight stem

coppiceable (for poles) For fruit trees

single stem or little branching nutrient rich leaf litter

Source: Djimde and Hoekstra (1988)


Multipurpose woodlots on very steep slopes

Tree/shrub ideotvne

Variable, depending on which products are desired from the woodlot mix. General requirements are for: capability to provide high yields of desired products (fuelwood, fodder, industrial materials, etc.) ease of establishment

rapid growth

adaptability to climatic and edaphic conditions of the site

effectiveness in controlling erosion

compatibility with other trees in managed associations

Plant arraneement and management

Other understorey economic plants or cover crops might also be included in the mix to control erosion during the establishment phase and/or to diversify the economic value of the plantation. The optimal spacing for different species needs to be worked out and establishment methods need to be evaluated with a view toward identification of low labour-requiring techniques.

Source: Minae (1989)

Multipurpose woodlots in Kenya

Recommendation domain: All land use systems, particularly for farmers in zones of wood products scarcity, and those close to major markets for these products. As demand for wood products increases with population in the high-potential highlands, such products may become economically competitive with [agricultural] crops for farmland. This will especially be tree for marginal lands, but near active timber/pole/fuelwood markets such products may be competitive even with [agricultural crops on] cropland. Development of multipurpose woodlots is proposed to achieve farm self-sufficiency in wood products, and to generate cash income through commercial sales. As woodlot technology at standard spacing for largeholders has already been developed for the high-potential highlands, we concentrate on high-density mini-woodlots which are attractive to smallholders.

MPT specifications

climatically and edaphically suitable

high growth rates at high density spacing

high quality wood for fuelwood and poles

growth habit appropriate for harvest as fuelwood and poles

Source: Minae and Akyeampong (1988)


Fruit orchards in Kenya

Recommendation domain: Larger farms of the tea-based and maize-based farming systems in the highlands Tree specifications

climatically and edaphically suitable

high fruit production

off-season fruit production (if possible)

early maturity and fruiting

ease of acquisition of planting material

pest and disease resistance both pre- and post-harvest

Source: Minae and Akyeampong (1988)

Intensive fodder banks with MPTS in Kenya; conceived as a mixture of woody and herbaceous species, densely planted and intensively managed.

Source: Minae and Akyeampong (1988)

As a store of cut-and-carry fodder to be used as a supplement during the dry season in Uganda

climatically and edaphically suitable palatable & nutritious coppiceable/pollardable vigorous growth/high leafy biomass Source: Djimde and Hoekstra (1988)

As supplementary fodder supply for more intensive management of calves & work animals. A small plot

protected by live fence, enclosing a fodder orchard consisting of a mixture of pod producing trees and leaf fodder producing perennial which can be intercropped with pasture legumes.

tolerant of temporary waterlogging (up to 2 months) tolerant of long dry seasons tolerant of cracking vertisols relatively fast growing

(Synonym: boundary planting)

General specifications climatically suitable edaphically suitable fast growing

pest & disease resistance

easy to establish

easy to manage

non-weedy (non-spreading)

early maturity (for desired product) high value products

High yield and quality of desired products: timber

poles fuelwood fodder

fruits, nuts, oilseeds fuelwood

industrial raw materials

marketable cash crops (with of without processing)

For cash crops in marginal lands (drvland or acid soils) distant from markets:

easy to establish


early maturity of desired product Compatibility with other crop plants non-allelopathic

deep rooting

compatibility with trees in managed hedgerow association

able to grow in relatively close association with other trees

minimal competition with nearby crops

non-spreading roots

non-spreading crown

not harbouring birds, other pests & diseases

Sources: Summarized from Kwesiga and Kamau (1988) and Minae and Akyeampong (1988)


Line plantings on bunds of rice paddies for green manure/mulch/fodder N-fixing

rapid growth

ease of establishment

light or easily management canopy for shade control

nutrient recycling capability through leaf shedding or pruning tolerant of waterlogging

tolerant of cracking soils

suitable as supplementary fodder during dry season (nutritious, palatable) Source: Kwesiga and Kamau (1988)


Living fences for pioneer cattle ranching system in Peru MPT specifications

ease of establishment

survival and rapid growth rate at close in-row spacing short time lag before achieving functional effectiveness non-competitiveness with adjacent pasture non-toxicity to livestock

fire resistance

yield additional by-products Source: ICRAF et ál (1982)

iving fences for cereal-cotton-cattle system in Uganda MPT specifications

Source: Djimde and Hoekstra (1988)

For integration of production with conservation functions stabilization of soil & water management structures in the Bijapur watershed of Karanataka, India (RR = resource rich; RP= resource poor) MPTS on water catchment bunds for timber. fruits. fodder edaphic suitability (vertisols: waterlogging, cracking)

climatic suitability (drought tolerant) limited competition with adjacent crops suitable phenology

limited height (can be taller on E-W rather than N-S bunds) not encourage birds to perch or nest good soil stabilizing features

minimal protection problems not harbour crop pests or weeds no root suckering

good soil micro-site enrichment characteristics high levels of plant N, P, K, Ca, Mg good litter turnover

local marketability/utility little branched

could be slower growing than fruit or fodder variants For fruit (RR & RP)

local processing potential (cottage or small village industry) early bearing

short harvest season (other systems may require long bearing season) free from pests & diseases

available during needed seasons (Oct, April-June) quick regeneration after cutting/browsing coppiceable

high harvest index (large proportion of annual dry matter increment goes into pods) free from pests & diseases

regular & reliable pod yields Source: ICRAF and ICAR (1986)

Trees on terrace risers in Bhaitan watershed in the outer Himalayas of Uttar Pradesh ease of propagation

low shade

restricted root competition

not to encourage pests

Source: ICRAF and ICAR (1984)

climatic suitability edaphic suitability

easy establishment (direct seeding or cuttings if possible)

nitrogen-fixing or other nutrient cycling capability no allelopathic effects

palatable nutritious digestible

able to develop broad canopy cover during fallow period browse tolerant

For tobacco farmine system (Tanzania) nematicidal or nematode-repelling properties not harbouring other pests For cotton farming system (Tanzania) insecticidal or insect-repelling properties not harbouring other pests

Source: Summarized from ICRAF et al (1982), Vonk (1983), ICRAF _e gá(1984), Minae and Akyeampong (1988), Djimde and Hoekstra (1988), Kwesiga and Kamau (1988), Min" (1988), Djimde (1988), Kwesiga and Sabas(1989)


Enriched fallow for the Chitemene, Maize-Cattle, Maize-small stock systems in Zambia

Recommendation domain: In transitional areas using hoe cultivation, where grass or bush fallow continues to be used for enriching the soil in the cropland, biologically and economically enriched fallows could be introduced. This is an agroforestry practice in which land that is not being cropped reverts to an improved

fallow which serves simultaneously for feed, fuelwood, or production of other tree products. There are two basic variants, the first being a hedgerow layout of coppicing fallow trees, appropriate where the system is expected to intensify into a continuous cropping system based on hedgerow intercropping, or where ox-ploughs may be used.... The second variant is broadcast planting of scattered fallow trees, an approach which has very low labour requirements, and could potentially be utilized when fallow periods are still rather long. MPT specifications

climatic & edaphic suitability

easily established by direct seeding or vegetative propagation

very rapid growth rate (to outcompete weeds)

N-fixing or other nutrient cycling ability superior to natural fallow (quicker regeneration) easily removed at end of fallow period (does not resprout if cut)

quick root decomposition after cutting (residual fertility effect)

effective weed suppression

yield of useful by-products

For tobacco crooning systems

nematocidal or nematode-repelling capability

high yield of fuelwood at end of fallow cycle (for flue curing of tobacco crop) If retained in crooland after fallow for mixed intercropping

compatible with crops

beneficial to crop growth

yield of useful by-products from side pruning for shade management Source: Kwesiga and Kamau (1988) & Kamau and Odra (1988)

13. LEYS

Technology description: Regulated leys are cultivated pastures established on croplands to provide fodder for a production oriented livestock system and restore soil fertility and structure. An efficient utilization of such pastures requires the introduction of fencing to control grazing. Agroforestry can contribute to this ley farming technology through the introduction of leguminous shrubs mixed with grasses in the pasture and through the development of living fences. In addition to the accepted benefits of N-fixing legumes on soil fertility, leguminous shrubs could facilitate pasture management, as their erect architecture enables them to avoid the problem of competition between grasses and legumes that is common to mixtures based on prostrate herbaceous legumes. If planted along contours, shrubs could also improve the erosion control property of pastures. In addition, such an arrangement would make it possible to have hedges as a permanent feature in the rotation cycle. When combined with maize stover they could improve the quality of the diet of cattle grazing crop residues. j)esmodium spp. are good candidates for these roles. The basic idea is that when the land is not being cropped it reverts to an improved fallow which serves simultaneously as a source of feed for grazing/browsing animals in a regulated ley system.

Recommendation domain: Regulated leys are a fairly sophisticated management approach to a stable mixed livestock/ cropping systems. It is appropriate only where intensive management is desirable and where tenure conditions permit fencing of cropland and controlled access to grazing land. MPT specifications

compatibility with grasses, herbaceous legumes & other fodder species pod production, leaf fall or other fodder production (during dry season) not harbouring important pests of the crops in the rotation

high biomass production of desired parts (leaves, pods)

ease of removal for subsequent cultivation

Additional specification for high rainfall upland sands

id tolerance, termite resistance

Addictional specification for low rainfall upland sands

drought tolerance

Source: Kamau and Odra (1988), Kwesiga and Kamau (1988)


For Bijapur, Karnataka, India

Recommendation domain: These specifications must be understood in the context of the highly stratified social system of the area, where the D&D team felt it was important to give special attention to the needs of the resource poor (landless labourers, gatherers, etc.), This technology is recommended for resource rich land users with sufficient land and for resource poor land users if land can be leased to them or otherwise made available. Tree specifications

growth and stature of woody species should allow intercropping for first 1 or 2 years trees and crops should be as compatible as possible trees should be multipurpose if possible, yielding raw materials for cottage industries, with some low value by-product for gatherers in the system main labour input requirements for management should occur outside the peak season Source: ICRAF and ICAR (1986)

Experimental cassava-based taungya system for the Sukuma agropastoral system in Tanzania Comment on the proposed intervention

More than the other lines of research, this one addresses a "socially" oriented intervention, i.e. how to develop

a socially acceptable way of growing trees in areas where tree planting is severely threatened by livestock damage. Ultimately the decision whether or not to adopt such a system will depend on a) whether, in the farmer's judgment, it represents an advantageous use of scarce cropland, and b) whether the customary respect shown by livestock herders for standing cassava fields can be used to protect trees through the establishment phase. A study should be conducted to determine the viability of this system and establish its recommendation domain before attempting dissemination. This does not necessarily mean that a biologically viable prototype should not first be developed, since realistic farmer assessments may not be possible until after they have seen a demonstration of a high-performance prototype.

Although successful systems of this type have been developed for the humid tropics, this is an experimental approach for drier environments like this one, and research should first validate the appropriateness of specific designs before commencing trials with farmers. Ultimately the decision whether or not to adopt this system would depend on the farmer's judgment that it represented an advantageous use of scarce land. Nevertheless, if a viable system of this type could be developed, it could have a major impact on tree production in areas where this is made difficult by extreme grazing pressure.

Technolo¢v description

Two fundamentally different approaches are possible, each requiring different tree selection and agronomic strategies: a) where the purpose of the system is mainly to grow trees under protected conditions (and, thus, where the yield of the intercropped cassava is of secondary importance and need not be maximized)--under such conditions the compatibility requirement might not be so stringent and a wider range of tree species might be used; b) where the yield of cassava is considered at least as important as the yield of tree products and the two must both be optimized, tree selection should be restricted to the least competitive/ most beneficial species. In either case, it should not automatically be assumed that the net effect of the trees will be a reduction in cassava yield on a per plant basis. Whether or not an LER > 1 is possible is an experimental question that depends on species selection, plant spacing, and management.

Tree ideotvne

capable of providing high yields of locally valued products (fuelwood, building poles, dry season fodder) relatively rapid growth with intercropped cassava (minimally must reach height at which it is no longer threatened by browsing within period of cassava cropping)

relatively low competition to intercropped cassava

deep rather than shallow-rooting

light or easily managed canopy for shade control

Adapted from Kamau and Odra (1988)

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