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Other papers

The dynamics of the shifting cultivation, rural poor, cattle complex on marginal lands in the humid tropics
Considerations of social, economic, institutional, and legal aspects of agro-forestry in Venezuela
Observations on indigenous and modern agro-forestry activities in west Africa
Some policy implications of agro-forestry: a Ghana viewpoint
Agro-forestry aspects of the establishment of the green belt around ouagadougou, upper volta
Agro-forestry in shifting cultivation control programmes in India
The forestry situation in Thailand
Constraints on the introduction of an agro-forestry element into traditional forms of shifting cultivation
Forestry and the rural community
AGRO-forestry activities in a multiple-use forest management project in the Philippines
The agro-forestry development plan and practices of picop
Agriculture, fuelwood, and conservation farming in the atzera range, lae, Papua New Guinea
Problems of agro-forestry in land-use planning
Participants and contributors

The dynamics of the shifting cultivation, rural poor, cattle complex on marginal lands in the humid tropics

John Bishop

Introduction

Much of the land in the wet tropics is marginal for agriculture, either because of steep slopes or of low soil fertility {Table 1). These lands are, however, normally covered with tropical forests which have the highest biomass and dry-matter production of all terrestial ecosystems (Table 2). This apparent contradiction is due to the fact that the nutrient level built up over time is maintained in a cycle between forest and soil (Herrera et al. 1978, Jorgensen et al. 1975).

When tropical forests are felled, the cycle is broken and the nutrient level decreases significantly after only a few years. This process of soil degradation proceeds fastest where temperatures are highest, rainfall greatest and slopes steepest. If forest vegetation is restored before soil structure and nutrient content decline below critical levels, the nutrient level can be rebuilt. The shifting field cultivationlfallow system, which has sustained much of humanity for millennia, is based on this principle and is the dominant farming system on marginal lands in the wet tropics (Buol and Sanchez 1978, Okigbo and Lal 1979).

An estimated 300 million ha of marginal lands in the wet tropics are at present under small farm. shifting field cultivation and produce basic foodcrops (corn. beans, rice, cassava, plantains, yams, sweet potatoes, cocoyam, taro, etc.) and fuelwood for more than 250 million people; figures which could easily double by the year 2000 (Bene et al., 1977). Production of foodcrops and fuelwood, as well as the generation of major cash income, capital and employment, are basic necessities which can only be met to a small extent from small permanent multistorey dooryard gardens (Atmosoedarjo and Wijayakusumah 1979), but require larger land areas under a shifting field cultivationlfallow system (King 1979), or under permanent agriculture.

Shifting field cultivation is an efficient long-term sustained yield farming system for population densities up to about ten people per square kilometre. The measure of efficiency is based on the use of the most limiting resource: energy. Shifting cultivators expend one calorie of labour energy to produce sixteen calories of food, while United States farmers spend one calorie of fossil fuel to produce only three calories of food (Greenland and Herrera 1977).

Shifting CultivationlRural PoorlCattle Complex

Throughout the wet tropics, however. the practice of shifting field cultivation is changing rapidly due to increased population growth rates and in-migration. The introduction of cash cropping has also resulted in a shortening of traditional fallow periods, and the introduction of grassland cattle production has resulted in a further reduction of land area available for shifting field cultivation (FAO 1978).

TABLE 1. Land Area and Soil Fertility Status of Major Climatic Regions in the Tropics (After Norman 1979)

a A month with over 100 mm of rainfall is regarded as wet (precipitation exceeding evapotransporation).
b High base status soils (vertisols, mollisols, aridisols and aridic groups), allovial soils (aquepts, fluvents and others), moderately leached soils (andepts, tropepts, and others).
c Low base status soils (oxisols, ultisols, alfisols). dry sands and shallow soils (psamments and lithic groups).
d Million hectares (percentage).

TABLE 2. Dry Matter Production of Natural Vegetation in Different Climates (After Holliday 1976)

As human populations and expectations increase, fallow periods are shortened, accelerating at an alarming rate soil deterioration and infestations by weeds, pests and diseases, and critically decreasing basic foodcrop yields precisely as needs are increasing. This decrease in yields as a consequence of the shortening of the fallow period often makes the clearing of more unused forest land more rewarding than continuing the cultivation fallow cycle for more than about two or three cropping cycles on the same site (Bishop 1978, USAID 1978).

In Latin America after the second or third cropping cycle (approximately twenty years), land is frequently converted to grass pasture often to be sold to large cattlemen, and the small farmers migrate to new forest land to repeat the same process. This is done because the old land has passed the point of diminishing returns for basic foodcrop production, but can still be used for large-scale cattle production on grass pasture for another twenty to forty years in an ever more extensive grazing system. The grass' pasture, however, cannot be sustained and runs a "downhill" course due to continuous soil deterioration and multiplication of weeds and pests, and after twenty to forty years is, for all practical purposes, completely degraded (Parson 1976).

Not only is degradation of already "developed" lands reducing existing potentials, but also the limit of the shifting cultivationlcattle frontier is being quickly reached in many areas of the wet tropics. In these areas, the shifting cultivation, rural poor, cattle complex is the major underlying cause of accelerated spontaneous colonization of marginal land, natural resource degradation, human resource impoverishment, and rural to urban migration Bishop 1982, Bishop et. al. 1981).

The spontaneous colonization of marginal lands in the wet tropics, particularly in Latin America, can be divided into three stages, first an extraction phase when small farm colonization and logging begin in earnest, until in-migration ceases. The second stage is an expulsion phase, when free forest land is no longer available, natural resources become extensively depleted and production of foodcrops and small farm fuelwood shows severe signs of stress. This culminates in an intensive expulsion of small farm families towards remaining frontiers or urban centres. The third and final stage is an exhaustion phase, when income from continuously decreasing cattle stocking rates no longer equal the ever-increasing labour costs for weed control. Today, many of these degraded grass pastures cannot be economically maintained and are being abandoned (Bishop 1979).

It is quite possible that within the next two decades most marginal lands in the wet tropics will be degraded, given the intensity of colonization and the vast scale on which tropical forests are being transformed into extensive "downhill" grass pastures at high social and ecological costs (Myers 1980, Walton 1980). When the colonization of the remaining tropical forests has been completed, most of the rural poor will be no better off economically, only twice as numerous! As the shifting cultivation, rural poor, cattle complex is the process that is degrading so rapidly the marginal land resources throughout the wet tropics, improving mixed small farming systems must be addressed as a priority issue.

Successful long-term sustained yield systems on marginal lands in the wet tropics depend on stabilizing soil structure and erosion, controlling multiplication of weeds, pests and diseases, and maintaining soil nutrients and organic matter at levels suitable for each type of land use. These levels inevitably change from those generally found under natural forests and may display cyclic variations; they cannot, however, be allowed to decline continuously. Solutions to these problems are some of the most difficult challenges facing tropical agriculture today.

Legume ForagelFuelwood Fallows

One promising innovation is to intensify land use under shifting field cultivation with tropical forest sheep on legume foragelfuelwood fallows (Bishop 1980, Bishop 1982).

Forage and fuelwood legumes increase soil aeration, organic matter, nitrogen and available phosphorus, control soil erosion and leaching, as well as provide a break in cropping that checks pest, disease and weed build-ups (Sprague 1976). Tropical forest sheep improve soil fertility by depositing organic matter which stimulates legumelRhizobium symbiosis and by supplying faecal micro-organisms which mineralize crop residues (Bredero 1977). In addition, tropical forest sheep cause little soil compaction and erosion, and produce high quality food protein by grazing legume cover forage, besides generating cash income, capital and employment for small farmers (McDowell and Hildebrand 1980).

In Amazonian Ecuador, studies are being carried out on the intensification of fallow periods by grazing African tropical forest type sheep (studies began in November 1979) on the Asian tropical forest legume cover forage, Desmodium ovalifolium (studies began in April 1978) under American tropical forest legume fuelwood trees, Inga edulis (studies began in February 1976).

Desmodium ovalifolium is a commercial Asian legume cover crop used under rubber and oil palm, as well as a promising legume forage in the American wet tropics (Bishop 1980a; CIAT 1981). Desmodium ovalifolium is a vigorous, very stoloniferous, non-climbing, perennial cover which cascades over banks and steep slopes effectively binding soil and controlling erosion. In addition, due to its heavy seed-producing ability, vigorous stoloniferous growth, medium palatability, and extreme tolerance to shade and low fertility soils, it is one of the most persistent legume forages under forest grazing in the wet tropics.

The nutrient cycling function of a fallow depends very much on the density and extent of its root system. The present fallow system combines the dense, shallow-rooted legume cover forage Desmodium ovalifolium with the deep-rooted legume fuelwood tree Inga edulis. A deep rooting system has the double function of bringing up nutrient ions released at depth and of trapping downward-moving ions when an excess of water leads to leaching (Akin 1979).

The protective function of the fallow depends very much on providing effective and continuous soil cover. Inga edulis trees coppice well, protect the soil from the full force of high intensity tropical rains, and provide shade to smother crop weeds as well as to lower soil temperatures which in turn reduces soil organic matter mineralization rates (Ahn 1979).

Inga edulis is a very fast growing legume fuelwood species. Its trunk diameter grows in excess of 5 cm per year and provides excellent fuelwood and charcoal in less than six years. Inga edulis is commonly used throughout the American tropics for its fuelwood and as a shade tree for coffee and cocoa. Also its seeds are enclosed in a sugary, edible pulp and its flowers are rich in nectar and attract bees (Anon. 1980).

Desmodium ovalifolium and Inga edulis are both easily established from their abundant seeds (without inoculum or scarification) and are interplanted following weeding during the food cropping period (Fig. 1). Desmodium ovalifolium is established at a rate of 4-5 kglha with a pinch of seed sown every metre and Inga edulisseeds are planted every 8 metres.

Tropical Forest Sheep Among the world's ruminants, sheep are second only to cattle in their production of highquality food protein (Winrock 1977). The majority of the world's 1 billion sheep have wool and are in the temperate zone. However, an estimated 100 million "hair sheep" (Winrock 1979) are kept in the lowland tropics of Africa, America and Asia (Tables 3-5). Although thought to have originated in Asia, hair sheep were widely distributed throughout tropical Africa by early Christian times (Grigg 1974).

TABLE 3. Number of Tropical Hair Sheep in Selected Countries of the American Tropics (Mason 1980, Winrock 1979)

TABLE 4. Number and Distribution of Tropical Sheep in Indonesia^a (Mason 1980)

a 96 per cent of sheep in South-East Asia are in Indonesia.

FIG. 1. Average monthly precipitation in the Ecuadorian Amazon and cropping sequence in an eight-year field rotation system (starting a new half ha field each year)

TABLE 5. Number of Tropical Hair Sheep and Cattle in Selected Countries of West Africa

Epstein (1971) identifies two general types of thin-tailed hair sheep in Africa: the West African "forest type" and the Sahelian "savannah type". The African forest type sheep were introduced into the American tropics on slave ships in the seventeenth century (Bradford and Fitzhugh 1981, Mason 1980). Tropical forest type sheep are hardy and well adapted to hot humid climates, being uniquely tolerant of trypanosomiasis, haemonchosis, and foot rot (Hill 1980).

Another important characteristic of tropical-forest sheep is that they cause little soil compaction and erosion on marginal lands of the wet tropics. One of the consequences of continuous cattle grazing, coupled with high-intensity tropical rains, is the progressive deterioration of soil structure, resulting in crusting, low infiltration rates, and accelerated soil erosion even on gentle slopes. Cattle are also less agile than tropical forest sheep and only climb steeper slopes when driven by hunger. Cattle, therefore, overgraze pastures with gentle to moderate slopes and the steeper hillsides become corrugated or honeycombed by closely spaced cattle paths. These zigzag cattle trails lack vegetative cover and become unstable and subject to sliding, and also collect runoff water, causing accelerated erosion and gullies (Bishop et al. 1981, Bishop 1982).

In the studies in Amazonian Ecuador referred to above, the breed of sheep used is Red Afro-Colombian X Barbados Black Belly. Tropical forest sheep accept less palatable forages, such as Desmodium ovalifolium to a greater extent than cattle. The small size, early maturation, high fecundity and resulting high offtake of tropical forest sheep also fit well the grazing needs in small farming systems in the wet tropics. The Upper Amazon countries of Ecuador, Peru and Bolivia have large sheep populations which are mainly found on small farms (Tables 6-7).

Red Afro-Colombian hair sheep were introduced into the Ecuadorian Amazon beginning in late 1979. By mid-1980, the flock numbered twenty purchased ewes and one purchased ram. In early 1981, two Barbados Black Belly rams were imported and by mid-1982 the flock had increased by natural multiplication to over 100 head. Young ewes lambed for the first time between the ages of 11 and 13 months, with a lambing interval of between 6 and 8 months and a lambing rate of 1.35 to 1.80 lambs per litter. The larger the litter size, the longer the lambing interval. Male lambs reach market weights of 40-45 kg in 11 to 13 months. The sheep are adapted to the ever wet climate and foot rot has not been observed.

TABLE 6. Number of Sheep and Cattle in the Upper Amazon Countries of Ecuador, Peru, and Bolivia (Delury 1978)

TABLE 7. Percentage of Farms and Sheep by Farm Size in Ecuador (Arias, 1978)

Short lambing intervals (every six months), multiple births (1.35 lambslewe), early maturation (twelve months), and year-round breeding help to make tropical forest sheep three times more productive than cattle grazing perennial forages in the wet tropics. A comparison is made in Table 8.

In addition, the conversion of solar energy into plant dry matter in the wet tropics can be three times as great as that of temperate and dry tropical regions (Table 2). In the wet tropics, where there is a continuous thermal and hydrological growing season, perennial forages are photosynthetically fully active throughout the year and yields reflect actually realized performances. In temperate and dry tropical zones, maximum yields of pasture are 20 to 25 tlhalyr, as against 60-80 tlhalyr in the wet tropics (Cooper 1970).

Tropical forest sheep in the wet tropics should, therefore, be capable of producing an offtake (kglhalyr) considerably higher than that of cattle grazing perennial forages in temperate or dry tropical regions.

Transfer of Improved Technology

Current efforts to transfer technology to small farmers mainly employ the demonstration technique on more progressive farms. While this technique is relatively easy to execute, the few farmers that benefit are those with better incomes. The resulting effect tends to widen the gap between the rich and the poor, as technology does not easily "trickle down" to poorly educated marginal small farmers.

The mass training of small farmers is essential for improved management of marginal lands in the wet tropics and is one of the most difficult challenges facing national institutions. In Amazonian Ecuador, human resource development for improved land resource development is aided by the provision of effective educational materials for mass small-farmer training programmes. Small-farmer training materials are being prepared on "Multistorey Dooryard Gardens with Backyard Poultry and Swine" and "Fieldcrops in Rotation with Tropical Sheep on Legume ForagelFuelwood Fallows. "

TABLE 8. Comparison between Tropical Sheep and Tropical Cattle

The small farmer training materials aid ongoing integrated rural development projects through local adult education centres, radio education courses and practical classes in rural schools. The effects of the training materials are:
(a) transfer of improved technology;
(b) motivation of the small farm population towards agricultural vocations and thus reduce rural/urban migration; and
(c) enhancement of adult literacy programmes by provision of practical auxiliary reading materials.

References

Ahn, P.M 1979. "The Optimum Length of Planned Fallows." In H.O. Mongi and P.A. Huxley, eds., Soils Research in Agro-forestry. Nairobi. pp. 15-39.

Anon. 1980. Firewood Crops: Shrub and Tree Species for Energy Production. National Academy of Sciences, Washington D.C., p. 237.

Arias, E. 1978. "Diagnóstico Socio-económico del Medio Rural Ecuatoriano." Documento No. 5 Ganaderia. Programa Nacional de Regionalizacíon Agraria, Ministerio de Agricultura y Ganaderia, Quito, p. 249.

Atmosoedarjo, S., and K Wijayakusumah. 1979. "Ecological Aspects of Agro-forestry in the Lowland Humid Tropics: Southeast Asia." In T. Chandler and D Spurgeon, eds., International Cooperation in Agro-forestry. Proceedings of an International Conference, DSE/ICRAF, Nairobi, pp. 117-128.

Bene, J.G., H.W. Beall and A. Cote. 1977. Trees, Food and People. International Development Research Center, Ottawa. 52 pp.

Bishop, J.P. 1978. "The Development of a Sustained Yield Tropical Agro-Ecosystem in the Upper Amazon." Agro-Ecosystem, 4: 459 461.
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Bishop, J.P., R. Hudgens, and D Gow. 1981. "Dynamics of Shifting Cultivation. Rural Poor, Cattle Complex in a Humid Tropical Forest Life Zone." Research Note No. 2 (manuscript). Development Aiternatives Inc., 1823 Jefferson Place, N.W. Washington, D.C. 23 pp.

Bradford, G.E. and H.A.. Fitzhugh 1981. Hair Sheep: Genetic Resource for Tropical Agriculture. Winrock International Livestock and Training Center, Morrilton, Arkansas.

Bredero, T.J. 1977. "The Role of Farmyard Manures and Green Manures in Soil Fertility Restoration in the Humid Tropics." Abstr Trop. Agric., 3: 9-17.

Buol, S.W. and P.A. Sanchez. 1978. "Rainy Tropical Climates: Physical Potential, Present and Improved Farming Systems." Plenary Session Papers of the 11th International Congress of SoilScience. Edmonton, Canada. Vol. 2: 292-312.

CIAT. 1981. Informe CIA T. Centro Internacionai de Agricultura Tropical. Cali, Colombia, 124 pp.

Cooper, J.P. 1970. "Potential Production and Energy Conversion in Temperate and Tropical Grasses." Herb. Abst. 40: 1-15.

Delury, G.E. 1978. The World Almanac and Book of Facts. Newspaper Entreprise Assoc., Inc., New York. 976 pp.

Epstein, H. 1971. The Origin of the Domestic Animals of Africa. Vol. II. Africana Publ. Co., New York.

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Goodland, R. 1980. "Environmental Ranking of Amazonian Development Projects in Brazil." Environmental Conservation, 7: 9-26.

Greenland, D.J. and R. Herrera, 1977. "Shifting Cultivation and other Agriculture Practices." In Patterns of Use of Tropical Forest Ecosystems (manuscript). Soil Science Department, University of Reading, United Kingdom.

Grigg, D.B. 1974. The Agricultural Systems of the World: An Evolutionary Approach. Cambridge Geographical Studies No 5. Cambridge University Press, Cambridge. 358 pp.

Herrera, R., C.F. Jordan, H. Klinge, and E. Medine. 1978. "Amazon Ecosystems. Their Structure and Functioning with Particular Emphasis on Nutrients." Interciencia, 3: 223-230.

Hill, D.H. 1980. Production of Small Ruminants in the Humid Zones. International Livestock Center for Africa (ILCA), Addis Ababa. 23 pp.

Holliday, R.H. 1976. "The Efficiency of Solar Energy Conversion by the Whole Crop." In A.N. Duckham, J.G.W. Jones and E.H. Roberts, eds., Food Production and Consumption. NorthHolland Publishing Company. Amsterdam and Oxford. pp. 127146.

Jorgensen, J.R., C.G., Wells, and L.J. Metz. 1975. "The Nutrient Cycle: Key to Continuous Forest Production." J. Forestry, 73: 400-403.

King, K.F.S. 1979. "Concepts of Agro-forestry." In T. Chandler and D. Spurgeon. eds., Intemational Cooperation in Agroforestry. Proceedings of an International Conference. DSE/ICRAF, Nairobi pp. 1-13.

Mason, l.L. 1980. Prolific Tropical Sheep. Food and Agriculture Organization, Rome. 124 pp.

McDowell, R.E. and P.E. Hildebrand. 1980. Integrated Crop and Animal Production: Making the Most of Resources Available to Small Farms in Developing Countnes Working Papers, Rockefeller Foundation, New York. 78 pp.

Myers, N.1980. Conversion of Tropical Moist Forests. Report for the Committee on Research Priorities in Tropical Biology, National Research Council. National Academy of Sciences. Washington, D.C. 204 pp.

Norman, M.J.T. 1979. Annual Cropping Systems in the Tropics. University of Florida Book, University Presses of Florida, Gainesville. 276 pp.

Nye, P.H. and D.J. Greenland,. 1960. The Soil Under Shifting Cultivation. Commonwealth Bur Soils, tech. Commun, 51, Harpenden, United Kingdom. 156 pp.

Okigbo, B.N. and R. Lal. 1979. "Soil Fertility Maintenance and Conservation for Improved Agro-forestry Systems in the Lowland Humid Tropics." In H.O. Mongi and P A. Huxley, eds., Soil Research in Agro-forestry. Nairobi. pp. 41-77.

Parson, J.J. 1976. "Forest to Pasture: Development or Destruction?" Rev. Bio. Trop, 24 (Suppl. 1): 121-138.

Spears, J.S. 1979. "Can the Wet Tropical Forest Survive?" Commonwealth Forestry Review, 58: 165 80.

Sprague, H.B. 1976. "Combined Crop/Livestock Farming Systems for Developing Countries of the Tropics and SubTropics." Technical Series Bulletin, No. 19, Office of Agriculture, Technical Assistance Bureau, Agency for International Development, Washington, D.C. 30 pp.

USAID, 1978. Proceedings of the U.S. Strategy Conference on Tropical Deforestation. Sponsored by U.S. Agency for International Development, Washington, D.C. 78 pp.

Walton, S. 1980. "Replacing Trees with Wasteland: The Demise of Tropical Moist Forests." BioScience. 30: 377-81.

Winrock, 1977. The Role of Sheep and Goats in Agricultural Development Winrock International Livestock Research and Training Center. Morrilton, Arkansas. 223 pp.
- 1979. Hair Sheep Production Systems. Winrock International Livestock Research and Training Center, Morrilton, Arkansas. 117 pp.

Considerations of social, economic, institutional, and legal aspects of agro-forestry in Venezuela

Eduardo E. Escalante

This paper will give a broad outline of what has been done in agro-forestry in Venezuela up to the present time, as well as considering the social, economic, institutional, and legal aspects of this system there.

Venezuela is located in the northern part of South America, between approximately 2° and 10° N. Its area is 912,000 km² At the beginning of the 1970s it was estimated that of this area, 350,000 km² consisted of primary tropical rain forest of which 89 per cent was located south of the Orinoco River.

It is estimated that 74,000 km² of land north of the Orinoco River was originally covered by tropical rain forest, but at the present time only 30 per cent of this remains intact, the other 70 per cent having been deforested for the establishment of agricultural crops and grazing for livestock (33 per cent disappeared in only twenty-five years, between 1950 and 1975).

The other two biomes where agricultural activities take place are the savannahs and the deciduous forest; both of these are considered to be tropical dry forest, in which monoculture and extensive livestock grazing take place. They cover an area of approximately 250,000 km², mainly north of the Orinoco River.

Most other biomes are affected by slash and burn agriculture for the establishment of conucos as a result of the high pressure on land in rural areas. It can thus be seen that the development of land for agriculture is based on the destruction of the natural ecosystem, mainly in the tropical dry and rain forest.

In the last few years, the Ministry of Natural Resources has permitted the deforestation of 175,000 hectares per year but in practice this is only about a half of the area actually cleared, as most small farmers (campesinos) are not greatly concerned about obtaining legal permission from the ministry. In 1977, photo-interpretation using satellite images showed that 660,000 hectares of forest had been totally destroyed north of the Orinoco River. It is important to point out that less than 10 per cent of the deforested area is reforested annually.

Another aspect is the drain on the forest from firewood used by the campesinos for cooking. In 1976 it was estimated that 36,000 tonnes of firewood and 11,000 tonnes of charcoal were produced.

Agro-forestry is an old practice in Central and South America. The tropical forest is characterized by a high diversity of species and a multilayered structure, and it is thought that it was from this model that the indigenous cultures took their agricultural model of the conuco, establishing crop areas with a mixture of many species, annuals and perennials. Thus they mixed corn, cassava, beans, papaya, avocado and other tropical fruit species on the same place, and practiced a type of agro-forestry permitting them to obtain their daily necessities in food and wood.

This model was developed empirically. and without a scientific basis, to meet daily needs within the limitations of the natural environment.

In Venezuela, during the eighteenth and nineteenth centuries, large-scale cocoa and coffee plantations were established. These are crops which need shade for better growth and production, so the traditional practice was to make light clearings in the natural forest leaving the big trees (20-30 metres high) as shade. Later some other tree species were introduced which gave better results. These included Bucare (Erythrina spp ) and Guamo (Inga spp ) as well as some fruit species: Aguacate (Persea americana) and some citrus trees (Citrus spp ). The product of these fruit trees was a useful supplement to the farmers' income. Nowadays some forest species such as Cedro (Cedrela spp.), Pardillo (Cordia alliodora) and Mata de Raton (Glincidia septum) are frequently found as shade trees.

Renewed interest and the possibilities of introducing new techniques to improve the system make agroforestry a valid alternative in helping small farmers to improve their social and economical conditions, in motivating them to continue working the land and in stopping migration to urban areas, which is one of the worst problems faced by agriculture. The rural population has declined during the last seventy years from 60 per cent to 25 per cent of the total population, creating social chaos through the disintegration of the family life of the campesinos and leaving the land with insufficient hand labour. As a consequence. Venezuela now has to import 40 per cent of its annual food requirements.

A good example of the economical value of agro-forestry is in the crop associations located in the central region of the country, mainly in the state of Aragua around Lake Valencia, where the farmers usually grow crops between fruit plantations of avocado and mango, making an efficient use of space, time and radiant energy and also permitting a greater diversification of crop production during the year.

In this area there is a very strong production of fruit and vegetables, sometimes mixed, such as tomatoes, cantaloupes, onions, carrots, sugar beet, papaya and eggplants growing among the avocado (Persea americana), mango (Mangifera indica) and orange (Citrus spp.) trees.

In the upper valleys of the state of Carabobo and Yaracuy, citrus production is very high and the same systems are used. Here is also found one of the best examples of agroforestry, consisting of the use of stakes of Mata de Raton (Gliricida septum) as a support for plants of the passion fruit Parchita (Passiflora edulis), as this species needs to be able to climb upon a wire framework.

A preliminary study found that 300 stakes each about 2.5 metres high are needed to plant one hectare of passion fruit. If metal supports are used the cost per hectare will be approximately $1,400. By using stakes of Gliricidia septum the cost is reduced to $300 per hectare.

In the same system small stakes are used to guide the plants towards the wire; these are also made of Gliricidia septum.

Another crop that also needs small supports to prevent lodging is tomato. In the area mentioned above Mata de Raton stakes are used to build the empalado (a kind of fence to which the tomato plant is tied).

In open parts of the country trees can be seen in grazing fields. This is very important not only from the economical point of view, but also in providing shade and food for cattle.

Examples of the trees used in this kind of "silvopastoral" combination are Saman (Pithecellobium saman) which is commonly used for its shade for the animals and its highly nutritious fruit; and Guacimo (Guazuma ulmifolia) another species widely used in pastures because of the palability of the fruit and its high consumption by animals. Mata de Raton (Gliricidia septum) is very useful not only for shade but also for its value as forage. Studies have shown that its leaves contain a high percentage of protein. It should also be pointed out that this tree is by far the most widely used species for live fence posts in Venezuela.

Of economic timber trees the three species most frequently found associated with pastures are Apamate (Tababuia pentaphylla). Cedro (Cedrela odorata) and Pardillo (Cordia alliodora).

A study at present being carried out by the author in the Cerro 81anco farm in the lowlands of the state of Trujillo (south of Lake Maracaibo) has given the following preliminary results. A random sample of 45 trees from a total of 890 felled had an average height of 22.6 m with a clean bole of 10.2 m, representing 45 per cent of the total height. The average volume of timber was 0.78 m3 per tree giving a total volume of 695 m3 for the 890 trees. As the price per cubic metre is $163 this gives a total value of approximately $113,000 or $127 per tree at the farm. At the sawmill the market price would be $465 per m3.

From the legal aspect. two of the main limitations in forestry systems in Venezuela are related to forest reserves and land tenure. With respect to the forest reserves, they occupy a very large area of thousands of square kilometres, which cannot legally be used for agriculture or livestock grazing because of restrictions imposed by the Forest Law. Nevertheless, some of the reserves, such as the Ticoporo Reserve, have been settled by campesinos. These add a new problem, as any project directed towards the establishment of an agroforestry system needs to be consulted with them and their acceptance obtained. Similar problems exist with land tenure. Many small farmers are afraid of planting forest trees as they are merely occupants, and not owners of the land. If they plant trees, many of them will no longer occupy the site when the timber is harvested, or else they believe the harvest will be for the benefit of the landowner, and not for them.

In the forest reserve of Ticoporo, Empressa Mixta Forestal Compahia Anónima (EMIFOCA) and Compahia Nacional de Reforestacion (CONARE), with the advice of FAO, have proposed a project for the best use of the reserve. It includes some agro-forestry alternatives, but these are dependent on permission from the Ministry of Naturai Resources for their instrumentation.

A model has been proposed by CONARE in which. where the relationship of owner and occupant exists, profits from timber sales can be divided between the owner, the reforesting company (CONARE) and the occupant. with a different percentage for each of them.

Institutions like CONARE, Fonda Nacional de Investigaciones Agrapecuaria (FONAIAP), Ministerio del Ambiente y de los Recursons Naturales Renovables (MARNR), Universidad de Los Andes (ULA) and Electrificacion del Caroni (EDELCA) have shown interest in agro-forestry. At first some projects were initiated through the effort and interest of individuals, but in the last two years many of these agencies have included agroforestry projects in their annual plans.

In 1977, the Centro Nacional de Investigaciones Agropecuaria (CENIAP) and FONAIAP began some agroforestry studies in the zone of Barlovento in the state of Miranda; in this experiment, the relationships were examined between some annual and perennial crops. In 1981 CONARE held a meeting on Agro-forestry at Agua Santa, Trujillo, with the advice of ICRAF and FAO. In November of the same year the first seminar on applications of agro-forestry was held in Venezuela, organized by MARNR, CONARE, ULA, EMIFOCA and EDELCA. Several models were presented, and in addition a methodology proposed by ICRAF was discussed, which included as a first step the investigation of the study area so that appropriate agro-forestry alternatives for its development could be formulated.

Of special interest are two models developed by CONARE for the areas of Casadero in the state of Tachira, and Carache-Burbusay in the state of Trujillo. Both areas are highly eroded and at the present are under a reforestation programme with many forest species, mainly conifers and eucalypts. The idea is to establish pineapple and pastures between the trees; animals, such as sheep and goats, will later be introduced to graze the pastures.

Little attention has so far been given to academic studies of agro-forestry in venezuela, and so far there is no institution devoted to studies of the subject. University courses include some lectures and seminars on the subject. In the Agrarian Department of the Nucleo Universitario "Rafael Rangel" (NURR) at the University of Los Andes two students are working on this topic in theses for their degrees, under the advice of the author.

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