Original:Abstracts on Sustainable Agriculture 8

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Abstracts on Sustainable Agriculture (GTZ, 1992, 423 p.)[edit source]

Abstracts on agroforestry[edit source]

Acknowledgements[edit source]

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Review, Africa, Asia, agroecosystems, tree products, economics, policy issues, household inputs, agricultural inputs, employment, income, natural resources, social forestry, tree management, farmer, tenure


1. Tree products in agroecosystems: economic and policy issues.[edit source]

GATEKEEPER Series No. 28; IIED London, UK, 1991, 21 p.

This paper reviews trends in the use of, and rural reliance on, forest products; it examines the role of common property resources (PRs) as a source of these products; and characterises trends in the growing and management of trees in farming systems. Throughout, the impact of national policies and of programme and project interventions on these two sectors is examined in the respective sections.

Trees are planted and managed in the farming system, and in the neighbour wood to provide inputs needed in order to complement those available from on-farm resources. These non-forest sources of production are becoming increasingly important with the growing decline and degradation of nearby forests and the increase in demand for fuel, fodder, and other products.

There are three broad categories of use of forest products: direct use by the household as fuel, food, etc; inputs into the agricultural system such as fodder and mulch; and sources of rural household income and employment. These categories are discussed in detail in this paper.

Rural people draw much of their forest products from areas of forest, woodland and 'waste' land to which they have access as common property resources (CPRs). These outputs often constitute a major component of the overall agricultural system - filling gaps in the resource and income flows from other resources, and providing complementary inputs often critical to the continued functioning of agricultural and household systems.

The nature and magnitude of the relationship varies with the characteristics of the surrounding ecological and agricultural systems.

Examples from Asia and Africa are outlined.

Social forestry woodlots and joint management on forest land are explained.

In recent times farmers everywhere have sought to shift the production of outputs of value on to their own land by protecting, planting and managing trees of selected species. In many situations farmers now depend on their own tree stocks for some products, and on common property resource sources for others. The process of adding trees to farming systems has been accelerated or transformed by the growing commoditisation of fuelwood and other tree products, and the consequent emergence of the growing of trees as a cash crop. Examples in which tree planting occur in Asia and Africa are mentioned.

Within a particular agroecosystem, farmer involvement in tree growing appears to be largely related to changes in the availability and employment of land, labour and capital, and to the progressive commoditisation of tree products such as fuelwood and poles. Variations in tree growing patterns seem to reflect variations in the efficiency of operation of factor markets, different stages in the process of agrarian transition, and different patterns of tenure.

Concluding the author outlines implications for future policy considerations.

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Latin America, Asia, Africa, lowland tropics, plantation forestry, tree species, genotype environment interaction, tree breeding, tree yields,



2. Sustainable use of plantation forestry in the lowland tropics.[edit source]

In: Proc. of the Humid Trop. Lowlands Conference, Panama City, Panama, 1991, pp. 55-68

This paper lays down the principles governing successful plantation forestry in the lowland, humid tropics and seeks to address the issues which underpin sustainability: land capability, species choice, and management. Relevant examples are drawn from across the tropics.

While plantation forestry is often associated with industrial plantations the enormous expansion in social forestry is not neglected.

Accurate data for areas of tropical plantations are notoriously difficult to obtain. Gathering information from just over 100, mainly developing countries inevitably leads to a variety of definitions, confusion over units, optimism by some of equating seedlings supplied or planted with plantation established, lack of proper inventory, and so on. Nevertheless, from the available data, it seems clear that some 20 million ha of forest plantations of various forms have been established throughout the tropics and hotter subtropics in the last 10 years to give a global figure in excess of 40 million ha.

The virtual doubling of plantation forest area in the last 10 years arises from a massive social forestry program in India, though the quality and stocking of much new 'plantation' is questionable; a clearer picture of afforestation in tropical China; and programs of steady expansion in many countries. The bulk of the increase in the neotropics has occurred in Brazil, owing to the fiscal incentives program which ran from 1967 to 1986 and averaged some 300,000 ha per year from the early 1970s, but has since diminished to about one-tenth of this level.

An examination of tree planting schemes in the last 10 years shows a shift from one of replacement of natural forest formations, e.g. Jari, Brazil, to afforestation of already badly degraded land or natural savanna, cerrado, or grassland. This change is both laudable from a conservation point of view and reflects the fact that huge areas of land, since long deforested, are suitable for tree planting but not a lot else. The 40 million ha of Imperata grassland in Indonesia are a striking example.

Correct choice of species for a given site is fundamental to sustainable plantation forestry. Poor species choice will not only give poor yields about may increase risk of pest and disease damage. The ingredients of successful matching of species to site include first climate matching followed by attention to soil factors.

Industrial plantation forestry has been dominated by planting of a very few species in the lowland tropics. Indeed Pinus caribaea, Gmelina arborea, teak, and Eucalyptus grandis, E. camaldulensis and E. urophylla probably account for 90%.

The last 10 years has seen a significant broadening. Increased use of little tested species, promotion of nitrogen fixing trees, and advances in vegetation propagation technology have contributed to this.

In addition to variation due to provenance, and to all sources of variability, there is evidence of an interaction between the selected genotype and the site. The highest ranked provenances, varieties, families or clones will not necessarily be the same on all sites. This is known as genotype x environment interaction (GEI) and breeding strategies must recognize this feature.

Plantation forestry is a feasible silviculture in the lowland tropics provided attention is paid to sound practice to ensure properly matched species and sites and regular management inputs. It is not a cheap form of forestry, but with commitment over time to a project, including tree breeding programs, the large investment can repay in highly productive forest which appears to be sustainable on most sites.

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Latin America, Peru, study, project, forest management, Indians, land tenure, forestry cooperative


3. The palcazu project: forest management and native yanesha communities.[edit source]

Journal of Sustainable Forestry, 1, (1), 1992, pp. 97-123

This paper presents some of the background and the current operations of a novel management system incorporating landholders in tropical forestry.

The Palcazu Valley ist mostly in the Cerro de Pasco department in the central selva region of Peru.

The Palcazu project began in 1981 as a part of the larger scheme of regional development in the central selva of Peru. The regional plan was part of an even larger national plan for development of the tropical

Andean foothills.

The Palcazu forest project is socially as well as ecologically oriented.

The pilot program is taking place among native Amazonian Indians, the Yenesha of eastern Peru.

The two features of the forestry component of the Palcazu project that make it unusual are its involvement with Amazon Indians and the uniqueness of the strip-shelterbelt natural forest management system.

As this paper emphasizes, the social ties, knowledge of the forest, values placed on forest preservation, communal land tenure patterns, and willingness to work toward a common goal all militate for involvement of the project with the Yanesha in forest management.

For the forest management system to spread as a general model, people other than Indians will need to be included.

As this article attempts to make explicit, there are a number of ecological reasons why this kind of forest management should be promulgated. A balanced perspective would probably be that the social model proposed by the Palcazu project requires investment in quite different sectors than the usual forest exploitation with attendant high training costs, but that the extra effort may well be worth it if the outcome is rational forest management and stable social systems.

Technically, some problems have surfaced with the extraction system, especially the use of oxen with a population that has no tradition with them as draft animals. Oxen also require superior forage which involves an entire other subsystem of pasture maintenance just for the draft animals. There may be relatively low-cost and low-ecological-impact mechanical means of removing logs from the strips that can be developed.

Economically, the project still requires some subsidies both in supports to cooperative workers and in technical assistance. This support is currently being provided by World Wildlife Fund.

On the positive side, the market for preserved posts, initially very weak, has improved recently.

Failure of the forestry cooperative would have severe socioeconomic and political consequences for the Yanesha people, perhaps calling into question their very survival as an indigenous culture.

The Palcazu project points the way for future natural forest management projects, both in its unusual approach to forest management and in its social assumptions. Its survival during more than five years of national and regional political turmoil is largely due to the strong sense of ownership and commitment by the Yanesha cooperative members.

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Latin America, Mexico, study, tropical forestry, mahagony forest tenure, silviculture, tree yield, research, DESFIL, USAID


4. Opportunities and constraints for sustainable tropical forestry: lessons from the plan piloto forestal, quintana roo, Mexico.[edit source]

In: Proceedings of the Humid Tropical Lowlands Conference, Panama, 1991, pp. 65-83

The Plan Piloto Forestal (PPF) of Quintana Roo, an 8-year-old community forestry project on the Yucatan peninsula of Mexico, has been heralded as a model for sustainable tropical forestry. In order to extract useful lessons from this experience, it is important both to evaluate its current and future potential as a sustainable system, and to understand the opportunities and constraints that have defined its development.

Such an analysis should yield insights applicable not only to the continuing evolution of the PPF, but to the design of sustainable forestry projects elsewhere.

The first premise of this article is that the achievements of the PPF in community forestry are a product of both circumstances and the approach followed by the development team. The ecological characteristics of the forestand, the history of land and forest tenure and use in Quintana Roo created a favorable setting for community forestry based on timber harvesting. Nonetheless much of the success of the project can be attributed to the development philosophy, political connections, and long-term-commitment of the international team which initiated and has fostered the Plan Piloto Forestal (PPF).

The second premise is that while favorable ecological and institutional circumstances are necessary predictions for the establishment of successful tropical forestry projects, the long-term sustainability of forest activities depends on the design and application of appropriate silvicultural practices. This in turn, requires the capacity to define and acquire the necessary information on forest and species ecology and the impacts of forestry, and to develop and modify forestry practices accordingly.

During its first eight years the PPF has capitalized on existing opportunities and overcome a series of obstacles to accomplish its primary objectives of reorganizing forestry in Quintana Roo and contributing to socioeconomic development.

The benefits obtained from forestry activities by local people with secure tenure to their forest lands and decisionmaking power provide an incentive for managing forests with a long-term perspective.

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Africa, Ghana, study, taungya system, forest types, timber production, farmer attitudes, commercialisation


5. The taungya system in south-west Ghana.[edit source]

In: FAO Soils Bulletin No. 53, 1984, pp. 183-185

This study uses a rather narrow definition of intercropping agricultural and forestry crops without regard to who owns the agricultural crop, so as to bring out variations. It also sees the Tropical High Forest Zone in the country as covering South-West Ghana.

The taungya system, as it was developed in Burma, involves peasant farmers in afforestation or reforestation. This system interplants trees with agricultural crops, particularly the local population's staple foods, and so serves to satisfy the farmer's quest for arable land.

This type of forest reaches the coastline for approximately a quarter of its length and thereafter is separated from it by a belt of mangrove, scrub and coastal savanna formations, which fan out from west to east.

The zone is characterized by uniformly high temperatures, a rainfall regime with two peaks, mean annual precipitation ranging from 2135-3000 mm in the southwest to 1250-1375 mm in the northeast, and a high relative humidity. The humid environment maintained by the forest cover enables the cultivation of such cash crops as cocoa, oil palm, rubber and kola nuts. Cocoa and timber are the two major export commodities.

The taungya system was introduced with two objectives: to establish plantations of fast-growing, useful timber species and, second, to meet the peasant farmer's demands for arable land, using forest reserves where land was genuinely needed.

The size of the forest land allocated annually depended on the demand and the ability of the Forestry Department to cope with it. The latter was largely determined by the stock available. On a few occasions, farmers were asked to raise seedlings themselves.

In exchange for this privilege, farmers were asked to assist in establishing the plantation by preparing the site. They provided pegs, tended the planted tree crop alongside other food crops and also were governed by restrictions as to choice of species and spacing imposed by the Forestry Department. Farmers continued to receive allocations only if they adhered to these conditions.

Peasant farmers were generally pleased. These allocations gave them the opportunity to raise crops on relatively fertile forest land, increasing crop yields and improving the standard of living. Preparing sites in the Tropical High Forest is the most expensive operation in plantation establishment. The farmer did not reap the full benefit of this investment, but this did not concern him unduly. He had no opportunity cost for his labour and in so far as he could handle the work, involving his family, all his produce was profit. He expressed his gratitude to the forester by adhering to the rules, and generally becoming increasingly cooperative.

The large-scale reforestation scheme gave rise to yet another type of farmer, the big time city dweller, who used hired labour to cultivate food crops on the plantation sites.

The Forestry Department felled big trees and allocated plots to these "entrepreneur farmers" for a fee. The system resulted in a number of powerful farmers too difficult to control and consequently it failed.

The poor peasant farmer was excluded from these areas.

The advantages of the taungya system is that the forester may be able to raise a tree crop at a lower cost, and at the same time increase food production. The farmer always has the advantage of being able to use land which has been kept fertile under a forest cover.

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Latin America, Africa, review, book, field experience, agroforestry approaches, agroforestry planning methods

BUDD, W.D. et al.

6. Planning for agroforestry.[edit source]

Elsevier Science Publishers, Amsterdam, The Netherlands; ISBN 0-444-88634-6, 1990, price USD 89.75, Dfl. 175.00

This book incorporates selected contributions from an international symposium held in 1989 at Washington State University in the USA. It provides an overview of planting methods for agroforestry research and development projects, based on experience from the Centro Agron_mico

Tropical de Investigaci_n y Ense�anza (CATIE), CARE International, ICRAF, Washington State University, and the University of Wageningen (The Netherlands), among others. Discussions cover methods already in use and others currently under consideration.

Four chapters present various approaches to agroforestry planning, among these the diagnosis and design methodology developed at ICRAF. The rest of the book is devoted to accounts of field experience in Costa Rica, India, Indonesia, Kenya, Malawi, Sudan, and the islands of the Pacific.

Some of the key questions are:

- Planning for whom: Who are the farmers? What are their objectives and priorities? Or is the focus on the needs of the research, extension or government institution?

- Planning for what and in what context: Is the aim to design a project for research, for development, or both? Is the scale of planning at the macro (national, regional), meso (community, watershed, land-use system) or micro (household, farmer) level?

- What criteria should be used: How relevant are considerations such as biophysical and socio-economic indicators, adaptability/transferability, sustainability, institutional complementarity or scientific value?

- What method should be used: Techniques are available from fields such as land evaluation/landscape analysis, farming systems research and development, diagnosis and design, and agroecosystems analysis.

Each has strengths and they could be combined depending on objectives and resources.

As the editors state, "all these questions cannot be addressed with one planning method". However, there are a few important factors that must be considered in any planning exercise for agroforestry. These are integration, iteration, participation and sustainability. This book presents a range of both proven and new, innovative options.

It will be a valuable reference for anyone with a serious interest in agroforestry. It addresses the complexity of the planning process, focuses on critical issues and priorities, and provides much food for thought.

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Review, book, tropics, temperate climate, forests, sowing methods, aerial seeding


7. Sowing forests from the air.[edit source]

National Academy Press, Washington, D.C., ISBN 80-83796, Third Ed., 1986, 57 p. + annex

This report discusses reforestation in which the seed is broadcast from a plane or helicopter. It relies mainly on experiences in Australia, New Zealand, Canada, and the United States.

Sowing forest seed directly on the site to be forested is known to foresters as direct seeding, broadcast seeding, or broadcast sowing. The availability of chemicals for coating seeds to repel birds, rodents, and insects has made this a practical and more reliable method of reforestation.

In many parts of the world, deforestation has reached critical proportions. Africa, Asia, and Latin America have vast areas of once-forested land that is now denuded. Many have been left largely unplanted.

These enormous areas of virtually unproductive land are increasing.

Traditional revegetation methods should be applied more extensively, but the time also seems right for examining alternative methods.

Dropping seed from planes or helicopters is a well-known and well-established technique for sowing pastures as well as agricultural crops such as soybeans, wheat, and rice. Forests have also been established in this way. However, aerial seeding of forests is largely unappreciated, even by most foresters.

When conditions and species are right, and seed supplies sufficient, aerial seeding could be an important technique for reforesting large areas. It is easy to organize and seems well suited for reforesting sites that have rough terrain, debris, or difficult access. If it can be developed for sites and objectives in developing countries, aerial seeding could offer opportunities for vastly accelerating their reforestation programs.

Aerial reforestation is not a replacement for planting seedlings by traditional methods. It is best considered as a potential complement to conventional planting and to natural seeding, an additional tool for foresters to use when the needs, sites, and species are appropriate.

Sowing tree seed directly in the field is an old technique, but it was little used until the development of repellents to protect seed from insects, rodents, and birds.

It was learned that an additional coating of commercial insecticide would guard the seed against insects and rodents. These findings signalled the beginning of large-scale aerial seeding of forests in USA.

New Zealand demonstrates its success. Some of these forests have been established despite seemingly adverse conditions - for example, on steep slopes and on overburden from strip mines.

Aerial seeding is unproven in the tropics. The panel's purpose is not to recommend it over conventional reforestation techniques but to suggest trials of aerial seeding as a possible supplementary tool.

This book is not a textbook nor a practical guide to aerial seeding: details of the operations and techniques can be found in the selected readings. The purpose is to show administrators and foresters that this fast and often economical technique can be successful on appropriate sites, at least in temperate climates. The authors hope that the report will stimulate trials with, and research into, direct seeding (with or without the use of aircraft). In particular, trials are needed in the tropics where deforestation is most severe.

Aerial seeding presents many challenges for researchers, especially those in developing countries. While technology and techniques are developed and available, they are yet to be tested and adapted for use in those Third World areas now suffering devastating deforestation.

Because experience with aerial seeding of forests in the humid tropics is limited, little is known about predators and the best species to sow.

Aerial seeding could be an expensive failure unless small-scale trials show that direct seeding can be successful for the given species and sites.

Initially, these trials do not require use of aircraft. It is necessary only to broadcast a small amount of seed (pretreated, if necessary) on a small patch of the area being tested with conventional tree-planting methods.

The existing knowledge on seed coating and pelleting should be reviewed.

Successes and failures are reported in different situations.

Seeds can be targeted accurately (often within a meter or two). Thus direct seeding might prove feasible for filling in the widely scattered breaks in the forest left by slash-and burn farmers with useful species that best protect the vulnerabale soil.

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Review, tropics, subtropics, developing countries, land-use systems, land-tenure, shifting cultivation, sustainable agriculture, marginal lands, fallows, alley cropping, intercropping, trees, agropastoral systems, mixed farming


8. Agroforestry pathways: land tenure, shifting cultivation and sustainable agriculture.[edit source]

Unasylva 154, 38, 1986, pp. 2-15

From a project standpoint there are two fundamental ways of arriving at agroforestry: by integrating trees into farming systems or by integrating farmers into forests.

Appropriately selected woody components may contribute to both the productivity and sustainability of farming systems on marginal land in several ways: by enhancing the production of organic matter; by maintaining soil fertility; by reducing erosion; by conserving water; and, by creating a more favourable microclimate for associated crops and livestock. These "service roles" are above and beyond the direct "production roles" trees can also play in supplying food, fodder, fuelwood, building materials and other raw materials for rural industries. In traditional land-use practices, agroforestry is also important in maximizing and diversifying the productivity of even highly fertile lands. Intensive agroforestry systems are most commonly found in areas with a long history of population pressure, indicating their general efficiency as a land-use system.

All tropical land-use systems exhibit varying degrees of "leakiness" with respect to the cycling of nutrients held in the soil-vegetation complex, although systems such as irrigated rice paddies, permanent tree crops and forests are inherently more sustainable than others. It is a fundamental contention of agroforestry that trees have good prospects for plugging many of the holes in tropical farming systems. The degree of "infilling" can vary from slight to virtually complete. Essentially, the decision as to how many and which kind of trees it is profitable to add to the existing pattern of land-use depends on what useful niches for trees can be identified. An agroforestry "niche" in this sense has three components: a functional role within the land-use system; a place within the landscape; and a time within the life cycle of a particular land-use system.

Although many of the recent research thrusts in agroforestry have been directed toward the integration of trees into farming systems, agroforestry also has a role to play in the preservation of forests and the improvement of forest management systems. By providing farmers with a means of producing fuelwood, timber, building poles and other forest products on farmland, agroforestry can significantly reduce the demand on forests and natural woodlands. By doing this in ways that enhance and sustain agricultural productivity, agroforestry can also alleviate some of the pressure for the conversion of forest land into farmland.

Moreover, the integration of farmers into forest management schemes through the use of "compromise" land-use systems based on agroforestry may be one of the few realistic ways of sustaining forestry production on agriculturally pressured forest land.

The purpose of this article is to provide some mental images of the scope and potential role of agroforestry to serve as a background to the discussion of tenure issues. The main assumption is that the interactions between agroforestry and tenure issues are basically of two types: first, tenure factors may pose constraints to the realization of the potential ecological and socio-economic benefits of agroforestry in many land-use systems; and second, agroforestry may offer ways of resolving some existing tenure problems. Tenure issues are far more varied and complex than are reflected here. However, attention is focussed on some of the major changes in tenure that arise in conjunction with the main development trends in tropical land-use. These changes are then viewed in ecological and evolutionary perspectives.

Agroforestry can perhaps provide a simple, equitable, all-round solution in developing countries to the related problems of biomass energy supply, decentralization of rural industry, and the participation of pastoralists in national development.

The purpose of this article has been to raise some questions and provide some images for a positive approach to tenure questions in agroforestry.

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Pacific, Papua New Guinea, highlands, coffee, casuarina, food, ICRAF


9. Food, coffee and casuarina: an agroforestry system from the Papua New Guinea highlands.[edit source]

In: Agroforestry Systems in the Tropics; Kluwer Academic Publ., Dordrecht, The Netherlands; 1989, pp. 269-275

The paper describes an agroforestry farming system from the Papua New Guinea highlands (1,400-2,100 m) that has been developed by village farmers since about 1960 and has expanded rapidly since about 1970.

The majority of new coffee plantings made by smallholders in recent years have been in agroforestry systems that incorporate annual and perennial food crops, coffee and shade species. One such system is described here.

Major components of the system are numerous species of annual and perennial food crops (especially bananas), Arabica coffee and Casuarina oligodon. This system provides food, a cash crop and timber for construction and fuel.

C. oligodon is a fast-growing woody species that provides shade and timber for fencing, house construction and firewood. Its timber is easy to split and it burns well. The food crops include bananas (Musa cvs) (mostly triploid cultivars at these altitudes), taro (Colocasia esculenta and Xanthosoma sagittifolium), sugarcane (Saccharum officinarum), maize (Zea mays), highland "pitpit" (Setaria palmifolia), Amaranthus spp., Oenanthe javanica, Rungia klossii and others. Other components which may be present are nut pandanus (Pandanus jiulianettii) at altitudes above 1,800 m and oil pandanus (Pandanus conoideus) below 1,700 m. Pigs commonly graze under established coffee/casuarina/banana stands, but they are not a critical component of the system. Cassava (Manihot esculenta) is an important component of a similar system used on better drained soils, but not in this system on the wetter soils.

The basic structure of the system is that mixed vegetable gardens are gradually converted into coffee/banana gardens and eventually into coffee/casuarina stands.

The system described here is an extension of the traditional mixed vegetable garden system and it is the most widely practised of the recently developed integrated food/coffee/timber systems.

The overall performance of the system has not been quantified and hence not evaluated. Judging by the system's rapid expansion and widespread adoption, it is much more efficient than the officially promoted method of establishing coffee.

Because the canopy is maintained continuously by a sequence of faster and slower growing species, the need for weeding is minimized.

It is a conservation system in that the soil is protected from the direct action of the elements by continuous vegetative cover.

A reasonable level of managerial ability is needed to manage the system, but this is within the capability of most village growers. The level of management may be more difficult to attain when larger plantings are being established in a limited time, for example areas larger than 3 ha.

The research needs for this system are numerous and urgent, given that this farming system and similar ones are the most important ones that are used to establish new plantings.

Once farmer practices have been documented, innovations and potentially superior techniques need to be evaluated in controlled experiments. The growth pattern, nitrogen-fixing ability and ecological requirements of

Casuarina also require immediate study.

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Africa, Benin, Nigeria, Zaire, humid tropics, ICRAF, case studies, traditional farming systems

KANG, B.T. et al.

10. Agroforestry in africa's humid tropics - three success stories.[edit source]

Agroforestry Today, April-June 1991, pp. 4-6

This article describes three traditional agroforestry systems that combine multipurpose woody species with food-crop production on low-fertility soils in humid tropical Africa.

Efforts to increase food-crop production in the humid tropics by importing high-input 'modern' technologies have repeatedly led to disappointing results. For this reason, there has been a resurgence of interest in the traditional farming systems that have proven successful over the years.

The traditional slash-and-burn cultivation system of tropical Africa appears to be biologically stable as long as there is enough land to allow sufficient periods of natural fallow. The productivity of the traditional system declines rapidly with intensification of land use. In response to increasing pressure on land, farmers in some parts of the region have developed innovative production systems combining trees and crops. These systems are well adapted to prevailing soil and climatic conditions and help meet local needs for food and other products.

In Benin's Mono Province bordering Togo, the Adja people practice an improved-fallow system involving the replacement of the traditional bush fallow by densely planted oil palms (Elaeis guineensis). They grow these trees primarily to produce palm wine, which is often further distilled to make a popular local drink. Fruits from the trees also provide palm oil and the leaves are used for fodder, fencing, roofing, and baskets.

When the trees are felled, the trunks, roots, and other biomass left in the fields help renew soil fertility.

Acioa barteri is one of the three most important woody species in the bush-fallow system of southeastern Nigeria.

This shrub is planted or retained by farmers for nutrient cycling, weed suppression, staking, browse, and domestic uses.

Farmers plant acioa in hedgerows at intervals of 2 to 3 metres. At the beginning of the cropping cycle, the shrubs are burned and the stems cut to a height of 10 to 20 centimeters above ground. Some stems are collected for yam staking or for sale. Plots are then interplanted with yam, cassava, and sometimes maize. During the second cropping year, only the cassava remains, growing between the acioa hedgerows. In the third year, the hedgerows cover the entire field.

Farmers have practiced this rotational hedgerow-intercropping (alley-cropping) system for generations.

In the Bas-Zaire region of southwestern Zaire, pigeonpea (Cajanus cajan) is the third most important grain legume after groundnut and phaseolus beans. Pigeonpea is grown most intensively along with cassava in the Songololo area. It fills a crucial protein gap in the local diet between September and December before the harvest that follows a long dry season. After the pods are harvested, farmers apply the leaves as green manure on intercropped cassava.

This pigeonpea/cassava system of Bas-Zaire, which produces food and a little cash, may be a candidate for wider adoption. Experiments are in progress at M'Vuazi and Kimpese, Zaire, to test different spatial arrangements and timing of operations that might improve the traditional system.

These three examples show that farmers are fully capable of developing agroforestry systems that are well suited to their environmental and economic conditions - and without chemical inputs. Although the practices described here may not be as productive as more intensive, high-input systems, they achieve effective nutrient cycling and a degree of sustainability by combining deep-rooted woody species with food crops.

It might be possible to make these traditional systems more productive without losing their advantages, for example by adding low levels of fertilizer or other inputs, or by incorporating more nitrogen-fixing trees. There is a danger that these systems will be replaced by unstable 'modern' approaches, emphasizing short-term gains at the expense of long-term sustainability.

Research on these well-adapted traditional systems might lead to ideas for making them even better. Insights gained in these areas might also provide a basis for developing more sustainable and productive food-production systems in other parts of the region.

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Review, developing countries, fuelwood production, biomass energy, forestry, firewood species, farm forestry, community forestry, woodlots, land-use systems


11. Agroforestry and biomass energy/fuelwood production.[edit source]

In: Agroforestry Systems in the Tropics; Edt. P.K.R. Nair, Kluwer

Academic Publishers, Dordrecht, The Netherlands; 1989, pp. 591-597

The fuelwood situation in many developing countries has become alarming in recent times.

Recent studies have indicated that fuelwood cutting is second only to clearing land for agriculture as a major cause of deforestation.

Although fuel for cooking is the most important use of firewood, there are also other uses such as heating and lighting. Wood remains the main fuel source even in areas where forests are rapidly disappearing.

Trees and shrubs constitute the main source of firewood and other forms of biomass energy.

The problem of fuelwood shortage cannot be tackled in isolation from other aspects of rural development. The rather unimpressive performance of large-scale forestry and reafforestation programmes in the developing countries offers a good lesson.

The chances of a programme for fuelwood production being successful are greatly enhanced if it can be tackled the production not only of fuelwood but also of food crops.

Agroforestry can be of value in this context by:

- Incorporating and integrating appropriate species of woody perennials on farmlands along with other components of the farming system not in a competitive but in a complementary way;

- Integrating herbaceous crops and livestock on forest land according to the agroforestry management schemes so as to facilitate simultaneous production of wood and food crops; and

- Employing agroforestry techniques for reclamation of degraded lands and proper utilization of "wastelands".

Integration of appropriate fuelwood species on crop- and livestock-production units thus seems to be one of the best strategies for fuelwood production in the rural areas of the developing countries.

The greatest scope for improving their efficiency and obtaining tangible results in such a programme lies with initiatives in smallholdings.

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Review, book, Africa, Sahel, semi-arid zones, wood, legume species, natural regeneration, seed dispersal, seed predation, seedlings, seed germination, ecological conditions.


12. Regeneration of woody legumes in Sahel.[edit source]

Publ. of Botanical Institute, Aarhus, University in cooperation with DANIDA Forest Seed Centre, Denmark; ISBN 87-87600-35-8, 1991, 90 pp.

Woody legumes are a major feature of the semi-arid vegetation zones of West Africa and are very important economically in the region, but there is little published information on their natural regeneration. In this short book, Mr. Tybirk gives an overview of the regeneration strategies of 36 species found in West Africa's Sahelian and dry Sudanian zones.

Most of the legumes covered are indigenous, but the author also includes a few exotic species.

He discusses in separate chapters four phases in the natural-regeneration process - seed dispersal, seed predation, germination of hard-seeded plants, and growth of young seedlings. Based on the morphology of the diaspore, personal observations and the literature, he suggests that about 50% of the species covered are dispersed primarily by wind (hemi-legumes or samaras), nearly all species are dispersed either primarily or secondarily by passage through animals (most by ungulates and a few also by birds and/or primates), and a few species are secondarily dispersed by water.

The chapter on seed predation focuses mainly on predation by the beetle family Bruchidae, which has a major ecological and economic impact on woody legumes in the region. Lists of host-predator associations, host-predator-parasite associations, and seed-predation percentages are compiled from the literature.

The chapter on seed germination presents a general description of seed characteristics, dormancy-control mechanisms, seed banks in the soil, the germination process, and environmental factors affecting germination in the region. The chapter on seedling growth describes seedling development, vegetative regeneration, and environmental factors influencing growth.

The author emphasizes throughout the text that successful natural regeneration depends on complex ecological interactions involving dispersal, predation, germination, timing, grazing, fire, drought, soil type and other factors. He illustrates this complexity with many examples, some of which have important implications for ecosystem management. In the last two chapters, he discusses some general implications for long-term management and sustainable use of woody legumes in the region and provides a useful summary of regeneration characteristics for each species.

This book is a valuable contribution to our understanding of the natural regeneration of woody legumes in the Sahel. It should also stimulate further research in this important area.

1173 92 - 7/87


Developing countries, review, medicine, medical drugs, plant screening, forests, future strategies


13. Medicines from the forest.[edit source]

SPORE, 37, 1992,. p.5

The medicines in the United States show that 38% contained one or more products of plant origin as the therapeutic agent. Not all plant-derived drugs originated in the tropics but many did so and tropical forests are the richest potential source of new medical agents.

In Ghana, for example, more than 800 woody plants and many other herbaceous species are known for their medical properties. In Asia and the Pacific it is estimated that over 4% of indigenous flora has been utilized in traditional medicine. Latin America and the Caribbean, particularly the Amazon forests, are widely recognized for their contributions to human health in the past and their potential for future discoveries.

Over half of all plant species are natives of tropical forests.

It is estimated that half of the tropical forests have been cleared already. Destruction continues at 25 to 30 million hectares per year and the majority of plant species are vanishing before they have been recorded or investigated. The fund of knowledge carried by the forest dwellers who are displaced is also being lost.

New strategies must be developed to safeguard them.

The best hope for saving the remaining forests, the potential medicines that they contain and the peoples who know most about them may be in developing what has been termed "chemical prospecting". This permits commercial organizations to collect and identify plant materials with potential for medical uses in exchange for proper remuneration to the host country.

A similar strategy is to develop "extractive reserves" for sustainable development of forests where forest dwellers would collect rubber, nuts, coca, palm products and medicinal plants for sale. Brazil already has some such reserves and the World Wide Fund for Nature (WWF) supports a project in Cameroon in collaboration with the Cameroons Centre for the Study of Medicinal Plants. In eleven villages local people helped researchers investigate the plants of the surrounding forest, leading to a collection of hundreds of herbal remedies.

A UK company acts as a broker to find potential buyers for medicinal plants on behalf of tropical countries and has supplied major pharmaceutical companies with plant material from Africa and Asia.

To-date the main focus of activities appears to be in Central and South America and parts of Asia.

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Tropics, Caribbean, study, protein production, legumes, trees and shrubs, livestock production, CTA


14. Potential for protein production from tree and shrub legumes.[edit source]

In: Proc. of a Seminar "Forage Legumes and other Local Protein Sources as Substitutes for Imported Protein Meals", Kingston, Jamaica, 1987, pp. 50-55

This paper attempts to outline and give some information on the production of protein from tree and shrub legumes.

Certainly it does not attempt to cover all that is known about the more widely used and adapted legumes in the tropics. The author feels that there is need to investigate the legumes that are not so widely used, thereby exploiting the natural sources that may exist within the tropical cattle grazing areas.

In the tropics, forages usually have inadequate levels of proteins and minerals. The low levels severely affect livestock production, resulting in restricted growth rates, slow maturation and lower production.

The leguminous trees and shrubs have not only persisted but have become more diverse, with more than 18,000 known species. The tree legume family is thus one of the most numerous due to its adaptive traits and efficient use of the earth's natural resources, especially through the symbiotic mechanisms developed in its root structure.

Their rapid growth and high protein content makes them useful as a forage supplement. At the same time, the chemical linkages between the phenolic substances and the leaf proteins makes these resistant to bacterial attack, thereby making them more valuable as sources of nutrients.

Livestock producers are placing greater emphasis on the use of forage legumes in developing ruminant production systems. These legumes are fed either fresh, or are preserved in the form of hay or silage, to be used as a high protein supplement in the diet.

The tree and shrub legume species mentioned in this paper are:

- Aeschynomene americana L. is a tropical annual adapted to flooded soil conditions, exhibiting much diversity in plant form and growth habit.

- The crude protein content of Aeschynomene is higher than that of alfalfa, with beef cattle making greater weight gains on Aeschynomene than alfalfa in Florida.

- Codariocalyx gyroides, is a shrub indigenous to Southern Asia, reaching heights of over 3 m under fertile conditions.

- Cajanus cajan L. although not usually used as a forage legume in the tropics, does possess excellent characteristics. It is an annual or, more usually, a short-term perennial shrub growing up to 4 m high and woody at the base.

- Desmodium ovalifolium is of Asiatic origin and used widely in plantation agriculture as a cover crop.

- Desmanthus virgatus, a small nearly erect shrub, 2 to 3 m tall, found in the West Indies and from Florida to Argentina, is not widely used as a pasture species. The legume grows in sandy soils under a rainfall regime of 1000 - 1500 mm and prefers soils of pH 5.0 to 6.5.

- Indigofera hirsuta L. is a legume native to tropical Africa and Asia. The plant grows from 1 to 2.5 m tall, having an erect habit with few lower branches and with medium to fine stems becoming woody as the plant matures. The literature states that Indigofera can be used as a green manure or cover crop producing up to 5 tonnes of organic matter, and with proper management can make an excellent livestock feed, because of its high protein value and digestibility.

- Stylosanthes guianensis. The genus Stylosanthes has many species, which could be considered as shrub type legumes. Because of the apparent lack of importance of the other species, only S. guianensis is discussed.

- Gliricidia sepium (syn. Gliricidia maculata) trees grow up to 5- 15 m in height. The plant is native to Mexico and the West Indies, with a wide usage including live-fencing, wind breaks, shade trees and fodder.

- Leucaena leucocephala has it origin in Mexico but has spread throughout the tropics. It is a good browse species but prefers alkaline soil conditions.

The development work with tropical tree foliages as protein sources has been in the field of ruminant production systems. The positive results obtained in early trials proved to be sustainable under a wide range of commercial farm conditions and the rate of uptake of the technology by farmers has been rapid.

Attention should being given to their potential role in the diets of monogastric animals, with special emphasis on their use as supplements to liquid fibre-free feed resources such as sugar-cane juice and molasses. The first observations with pigs indicate that it is feasible to reach forage intakes that theoretically will satisfy the protein needs.

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Review, book, economic analysis, finances, incentive schemes, technical issues, economic modelling, cost benefit analysis


15. Agroforestry for sustainable production; economic implications.[edit source]

Publ. by the Commonwealth Science Council; Commonwealth Secretariat Publication, Marlborough House, London, SWIY 5HX, K, ISBN 0-85092-342-5, 1992, 417 pp., price £6.50

If a country's man-made assets (factories, machinery) depreciate faster than they are replaced, it is clearly living beyond its means and economic growth is not sustainable. In conventional economics no such concept applies to the depletion of natural resources. As they are used up, no decline in value is registered to reflect the fall in future potential production. For developing countries which are more dependent on natural resources for income, the danger of treating natural resources as valueless is even greater. There is a clear need for estimates of the costs and benefits of investment in their conservation and use, and Agroforestry for Sustainable Production addresses that need.

The book takes the form of a collection of papers presented at a Commonwealth Science Council workshop held in Swaziland in 1989. Part I is a discussion paper of the key issues involved in the financial and economic analysis of agroforestry. Part II includes papers about incentive schemes, technical issues, economic modelling and cost benefit analysis.

1176 92 - 7/90


Review, tropics, living fences, agroforestry technology, ICRAF


16. Living fences. A close-up look at an agroforestry technology.[edit source]

Agroforestry Today, 2, No. 3, 1990, pp. 11-13

Living fences are lines of trees or shrubs planted on farm boundaries or on the borders of home compounds, pastures, fields or animal enclosures.

Their mean purpose is to control the movement of animals or people. This purpose is what differentiates them from other agroforestry technologies based on trees planted in lines, such as boundary plantings, contour strips or hedgerow intercropping. Besides their main function to control human and animal movement living fences may provide fuelwood, fodder and food, act as windbreaks or enrich the soil, depending on the species used.

In Central America many farmers adopted living fences. The reasons are:

- Increasing population, decreasing farmland, and declining food subsidies were forcing more intensive agricultural production.

- Living fences do not require a large labour input - generally less than one day's work for planting and one or two hours a month for maintenance.

- Living fences provide a secondary benefit in the form of fuelwood.

Living fences/hedges are permanent, densely spaced, single or multiple lines of woody plants. They are regularly pollarded and trimmed.

Live fenceposts are permanent, widely spaced, single lines of woody plants that are regularly pollarded. They are used to support wire or other inanimate material, such as sticks or dead branches.

Living fences/hedges may be thicker than live fenceposts and may comprise more than one species, including trees, shrubs and smaller plants. They usually do not include wire or other inanimate material.

Farmers in Costa Rica and Honduras supplement their incomes by selling branches from their live fenceposts to neighbours wishing to establish new fences.

Many different tree species are used for living fences, depending on the ecological zone, the availability of stock and the specific needs of farmers. The most common species in Central America, northern south America and several Caribbean countries are Gliricidia sepium, Bursera simaruba, Spondias purpurea and Erythrina berteoana.

Living fences of G. sepium and Erythrina spp. are harvested to provide fodder for cattle, goats, rabbits and chickens (providing up to 25% of total intake), and the thicker branches of Gliricidia are used for fuelwood. Edible fruits and flowers can also be important, for example the 'jacote' fruit of S. purpurea, which is sold in markets in many Central American countries.

Living fences are a familiar feature throughout much of the African landscape. They appear on the densely populated hillsides of western Cameroon and in Rwanda and Burundi, marking small cultivated plots. In the dry rangelands of Northern Africa and the Sahel they form livestock enclosures and pathways to protect croplands and pasture from moving animals.

Species used for living fences in Africa include plants with good natural defence systems, such as long thorns, spines or unpalatability.

Examples are Dovyalis caffra (kei apple), Agave sisalana (sisal) and Euphorbia spp. Depending on site conditions and available plant material, a variety of other woody species may be used, including Ziziphus mauritiana, Z. mucronata, Commiphora africana, Erythrina abyssinica and Gliricidia sepium.

As the trees and shrubs grow, they must be pruned, usually on an annual basis. Otherwise, they may take up too much space or cast too much shade on adjacent crops. Root competition may also be a problem.

Well-established living fences may be difficult and expensive to remove, so they should be sited carefully before planting. If planted on a boundary, a living fence will affect more than one land user, so it is important that all land owners and users should agree on its establishment.

1177 92 - 7/91


Asia, Bangladesh, survey, evaluation, project, homestead agroforestry, land-use system, ICRAF


17. Homestead agroforestry in Bangladesh.[edit source]

In: Agroforestry Systems in the Tropics; Ed. P.K.R. Nair; Kluwer

Academic Publishers in coop. with ICRAF, Dordrecht, Netherlands; 1989, pp. 197-210

This paper evaluates the general conditions with respect to homestead agroforestry in Bangladesh and reports the results of a field survey.

Trees in the homesteads play an important role in the rural economy of Bangladesh. Often called homestead forests, such plantings are particularly important sources of fuelwood because fuelwood cannot be transported long distances from existing forest areas.

In the absence of other wood sources, improved village forestry and homestead agroforestry are important to the development of Bangladesh and the well-being of its people.

The Homestead Agroforestry Research and Development Project, being formulated by the United States Agency for International Development (USAID) - Dhaka Mission, has been proposed as a means to increase fuelwood supplies from homestead agroforests.

The many woody species grown in the homesteads are a significant source of fuelwood; they also provide fodder, building materials and other forms of wood. In the context of the prevailing shortage of fuelwood and excessive deforestation in Bangladesh, this homestead agroforestry system needs to be strengthened.

A field survey was undertaken to assess the prospects and feasibility of initiating a programme for the improvement of homestead agroforestry systems.

Concluding, the authors state that the conditions in Bangladesh seem favourable for the successful implementation of a homestead agroforestry project. Many persons there own their own homesteads and farms, thereby eliminating the disincentive of planting trees which someone else will harvest. Moreover the farmers are familiar with trees and their cultivation, and they believe that they have room to plant more trees.

Thus the level of basic knowledge and perception of opportunity among the farmers is satisfactory.

Channels of distribution for planting stocks must exist or be built.

Plant varieties better adapted to local growing conditions, generally improved growing stock and exotic can enhance programme success, although management practices for these plants must often be taught.

Existing government nurseries and extension services are appropriate institutions for distribution and teaching to start with.

Forest services have traditionally managed only trees grown in large forested areas. Many foresters consider working with other species unprofessional or demeaning. Foresters must shift part of their emphasis from the traditional forest trees to multipurpose trees which people desire. In addition, management practices for multipurpose and other species are important. These should include practices for individual and small groups of trees, as well as large planted areas.

The study shows that women play an important role in collecting fuel and in planting and cultivating trees. This implies that programmes should strongly consider modules to inform women of the new plant materials and to teach them new cultural and management practices.

1178 92 - 7/92


Review, book, guidelines, rapid appraisal, agroforestry research, extension

ABEL, N.O.J. et al.

18. Guidelines for training in rapid appraisal for agroforestry research and extension.[edit source]

Publ. of School of Development Studies, University of East Anglia

Norwich NR4 7TJ, UK, ISBN 0-85092-337-9, 1989, 117 pp.

The Commonwealth Science Council and the Forestry Commission of Zimbabwe collaborated in a training and research exercise in Shurugwi Communal Area in Zimbabwe in 1988, which resulted in the publication of "Guidelines for Training in Rapid Appraisal for Agroforestry Research and Extension", published by the University of East Anglia UK, and funded by the Ford Foundation.

The guidelines will help research and extension personnel in rapid appraisal methods for the development of agroforestry in peasant land-use systems.

The authors say that four key principles underlie the methods used: the first is "interactive research" whereby agroforestry interventions are identified and developed through working with and learning from farmers and the local community, as well as through conventional resource assessment. The second, "learning by doing", assumes that interactive research is best learned through real application rather than through lectures or classroom exercises and simulations. The third principle is "inter disciplinary", and is the key to successful interactive research.

Finally, agroforestry interventions are developed from an understanding of constraints and conflicts existing within the rural community over access to production resources.

This is a practical, easy-to-read, spiral-bound book, which takes the reader through the project step-by-step with charts, diagrams, clear text, and colour photos.

1179 92 - 7/93


Review, tropics, Central America, multipurpose tree, Erythrina, legume tree, CATIE


19. Erythrina (leguminosae: papilionoideae): a versatile genus for agroforestry systems in the tropics.[edit source]

J. of Sustainable Agriculture, 1, (2), 1991, pp. 89-109

Some of the most common uses of Erythrina species are discussed in this review related to specific agroforestry applications.

Although common throughout the tropics, the many species of Erythrina have not received much attention from researchers or development workers. Yet these trees of the family Leguminosae grow quickly and have considerable potential for supplying fodder, fuelwood and other products, for providing shade to coffee and tea, and for restoring eroded sites.

The genus Erythrina is of special interest in the development of agroforestry systems because of its adaptability to several uses (e.g., live posts for fences, shade trees for perennial crops such as coffe and cacao, forage for livestock, and others).

They thrive in hot climates, with mean annual temperatures from 30 to more than 38 C. Although well adapted to drought, they also grow well in areas with annual rainfall of up to 1200 millimetres. They can survive in soils with a pH of 8.7 and up to 0.11% salt concentration.

With their rapid growth and extraordinary nodulation, the Erythrinas are a good source of organic matter for green manure. Dry foliage contains from 1 to 3% nitrogen. When incorporated into the soil, it improves fertility, moisture, nutrient retention and general tilth.

In Costa Rica, for instance, the use of Erythrina for shading or nursing other crops is a common agricultural practice in both coffee and cacao plantations. There is a great deal of evidence showing its value as a "natural fertilizer" supplier and nutrient cycling helper. The calculated figures show that the return of nitrogen to the soil and nutrient cycle in coffee, cacao, and also in maize, can save up to 200 kg N/ha per year.

A considerable research effort in working with this genus has been done in the Tropical Agricultural Center for Research and Training (CATIE), Turrialba, Costa Rica through the Erythrina Project.

This research project supported by the International Development Research Center (IDRC) from Canada, produced a large amount of research and also compiled a substantial bibliography on the genus.

Field trials would be useful to compare different Erythrina species and varieties in terms of growth rates and fuelwood and fodder quality.

There is also a need to test the potential of different species as sources of good-quality paper and pulp.