Agroforestry and soil conservation needs of smallholders in Southern Zambia

An agroforestry and soil conservation needs assessment survey conducted in southern Zambia revealed valuable insight into needs, constraints and development options as perceived by smallholders themselves. Inadequate efforts to conserve soil are due to technical and socio-economic factors, they do not result from a lack of awareness of the widespread erosion threat. Fruit tree planting, windbreak establishment as well as the protection of the natural Faidherbia albida regeneration in cropland are popular agroforestry interventions whose positive effects are widely acknowledged. Forty-two perennial species were found to directly contribute to people's diet. Although local fuelwood and fodder shortages as well as the need for fencing are recognized only few respondents envisage agroforestry solutions such as fuelwood and fodder tree planting or live fencing. Most smallholders are interested in tree planting but have so far only planted few trees. Those planted are usually exotic fruit trees. Drought hardly, termite and browse resistant perennials adapted to smallholder tree planting must be provided by the extension services. The widespread exclusion of women from decision making and the lack of tenure security hampers female participation in agroforestry development and consequently threatens sustainable development altogether.     

The scope and potential of tree legumes in agroforestry

Tree legumes play a vital role in many agroforestry systems currently in use throughout the world. Because of their multipurpose nature they can be used to provide high quality fodder for livestock, nutrient rich mulch for crops, fuelwood and timber, microenvironment amelioration, ecosystem stability, and human food.Tree legumes are increasingly being used to provide fodder for livestock, as they have a number of unique characteristics which make them attractive for both smallholder and largescale livestock enterprises. Research and development efforts have concentrated on broadening the resource base by evaluating a greater range of tree legume genera, defining optimum management strategies, and developing appropriate systems which capitalize on the advantages of these species.This paper reviews the role of tree legumes in agroforestry, especially for fodder purposes, outlines the areas of current research focus, and endeavors to highlight some gaps in our knowledge which require further research effort.     

On-farm agroforestry research in extension programmes: methods used by BAIF in India

The BAIF Development Research Foundation initiated an agroforestry extension project in Pune District, India in 1984, following earlier on-station research on leuceana-based alley-cropping systems for fodder. In extension meetings, farmers expressed a strong preference for planting a wide range of multipurpose trees on farm bunds and borders rather than single-species alley-cropping. Researcher-managed trials of proposed multipurpose species grown with crops were initiated, but were of limited value. An alternative approach to research was begun in 1988. This approach included a survey of agroforestry practices established by farmers through extension, and collection of data on crop yields by distance from the tree line from a sample of these plots. Research methods are described and modifications suggested for improving the quality of this type of extension-based research.     

Agroforestry in Europe: a review of the disappearance of traditional systems and development of modern agroforestry practices, with emphasis on experiences in Germany

Agroforestry is a new name for a rather old practice. From a historical point of view, various agroforestry systems existed in Europe, of which the wood pastures (Neolithicum), the Dehesas in Spain (~4,500 years old) and the Hauberg of the Siegerland (established in the Middle Age) are the most prominent. Other widespread systems in Europe were hedgerows, windbreaks and Streuobst (orchard intercropping). Due to mechanisation and intensification of agriculture, trees have been progressively removed from agricultural fields and traditional agroforestry systems slowly disappeared. Today, agroforestry systems are again increasing in interest as they offer the potential to solve important ecological and, especially, biodiversity problems, while at the same time enabling the production of food, wood products and fodder for cattle. Although agroforestry systems offer many advantages, many farmers are sceptical of these systems and are critical and risk-averse with regard to adopting new practices. However, in comparison to traditional systems, modern agroforestry systems can be adapted to current farming practices. By selecting suitable trees and appropriate tree management, high-quality timber can be produced without influencing agricultural crops excessively. In future, agroforestry systems will become increasingly important as they offer the prospect of producing woody perennials for bioenergy on the same land area as food and/or fodder plants, while enhancing overall biodiversity.     

Influence of umbrella pine (<Emphasis Type="Italic">Pinus</Emphasis><Emphasis Type="Italic">pinea</Emphasis> L.) stand type and tree characteristics on cone production

Most umbrella pine (Pinus pinea L.) stands are managed as agroforestry systems, whose main production is fruit, due to the edible and highly nutritious kernels, and are frequently associated to natural or seeded pastures and grazing. The stands have low density, in order to enhance crown growth and fruit production. Nevertheless, cone production, both with regard to number and weight, varies greatly between stands, trees and years. In this study were selected three agroforestry systems, representative of umbrella pine stands whose main production is fruit, and one stand representative of the timber production system, where fruit is the secondary production. It was evaluated the variability in cone production as a function of the tree’s diameter at breast height and crown diameter and the individual tree’s competition status. The results indicate that stands managed in agroforestry systems with lower competition and individuals with larger diameter at breast height and crown diameter tend to produce more and heavier cones per tree. The first two principal components of the principal component analysis explain 84 % of the variance in cone production, trees’ dimensions and competition index. Tree competition status has a negative impact on production per tree.     

Incorporating agroforestry practices in the management of walnut plantations in Dauphiné, France: an analysis of farmers‘ motivations

The Dauphiné province in south-eastern France is a major area for walnut orchards. Growers manage their orchards with some specific agroforestry features: grafted walnut trees may be pruned to form a bottom log with a timber end use (dual purpose trees), and intercrops may be grown between the tree lines. These agroforestry practices are however only partially adopted. Three surveys were conducted in 1993, 1995 and 1996 to elicit the farmer motivations for adopting or rejecting agroforestry management features. The walnut industry is a key activity in two parts of Dauphiné: the Isère valley, and the Diois basin. The reasons for adoption of agroforestry practices are discussed. In the Isère valley, the priority is given to walnut production in specialised farms, and the extension services are opposed to agroforestry practices. In the dryer Diois area, the main explanations for agroforestry adoption were the welfare of the farmer family, the age of the farm manager, and the contribution of walnut production to the family income. Dual purpose management schemes were characterised by extended investment return delays, but proved to be the most rewarding schemes when practised with intercrops. A very extensive tree management with few pest control operations improved the profitability. Intensive orchards had a low bequest value at the time of inheritance, in contrast to dual-purpose orchards. The age of the farmer at planting time appeared to be a key criterion for agroforestry management adoption. This revised version was published online in June 2006 with corrections to the Cover Date.     

Testing an ecologically based classification tool on fruit-based agroforestry in northern Thailand

Ecologists are increasingly using multivariate analytical approaches to reveal relationships between communities. These methods have promise in other fields as well. The use of multivariate methods to delineate relationships and classify an agroforestry system was tested among fruit-based agroforestry gardens in northern Thailand. Data on crop species composition, species abundance, perennial-crop age groups, and other physical and ecological factors from 82 gardens in three villages in a Highland watershed in northern Thailand were used in this study. Using Hierarchical Cluster Analysis the gardens were divided into clusters, each representing a different garden type (or fruit-based agroforestry subsystem). Non-metric multidimensional scaling (NMS) analysis was used to assist in the interpretation of classification groupings and analysis gradients. The NMS analysis shows overall crop diversity, herbaceous food crops, size and market potential of the fruit planting as important classifying factors. However, this analysis did not produce as clear distinctions as hoped among gardens in a continuum of gradually changing and overlapping characteristics.     

Agroforestry in central,northern, and eastern Europe

Integrated management of natural resources and the multiple use of trees and forests have prevailed in most European societies since prehistoric times. In the Middle Ages, expanding and intensified agriculture resulted in the separation of trees from agricultural fields. During the last century, with the introduction of sustainable and highly productive forest management, the goal of increased wood production has been achieved in most parts of central, northern, and eastern Europe. Today, agroforestry is not considered to be an important land-use option within the region; however, there are many practices that could rightfully be classified as agroforestry. These include tree/crop systems in which trees provide products and/or environmental benefits, and tree/animal systems in which animals are grazed in forests or open woodlands.The future seems to offer some prospects for agroforestry. Large areas, hitherto used for food production, are either marginally suited to agriculture, or will probably be taken out of production due to agricultural policy considerations. Agroforestry may, at least in part, offer alternatives for the use of such lands. The availability of (surplus) fertile soils, capital, and labor may provide incentives for site-adapted forms of agroforestry, including improved fallow management. The focus of such systems would be on maintenance of biodiversity in the landscape, environmental protection, recreation, and product diversification.There are numerous expectations as to what agroforestry might provide for the land holder and for society as a whole. These expectations should be carefully analyzed and evaluated prior to political decisions on future land use. The promotion of agroforestry requires overall investment; agroforestry does not happen by itself. A set of integrated actions — not isolated efforts — must be implemented if agroforestry is to become a successful land-use option.     

Homestead tree planting in two rural Swazi communities

Tree planting practices were investigated on a total of 95 homesteads in two communities in rural Swaziland. Information was also collected on socioeconomic characteristics of the homesteads. In both the study areas, Sigombeni and Bhekinkhosi, there was considerable variation amongst individual homesteads in size, relative wealth (as indicated by cattle and motor vehicle ownership), and amount and types of trees planted. Eighty-five percent of all homesteads in Sigombeni and 73 percent in Bhekinkhosi had planted at least one tree. Common forms of planting included small woodlots, fruit trees, and ornamentals. Virtually all the woodlots consisted of two introduced wattle species (Acacia mearnsii and A. decurrens). The most commonly planted fruit trees were avocadoes, bananas, and peaches. No complex or labor-intensive agroforestry practices (such as maize/leucaena intercropping) were observed. There was some evidence that the poorest and newest homesteads were the least likely to have planted any trees and that the richest homesteads were the most likely to have planted woodlots. The results indicate that forestry research and extension efforts should take into account homestead characteristics, and strive to offer a range of tree planting options that vary in input requirements, labor needs, and complexity.     

Improving adoptability of farm forestry in the Philippine uplands: a linear programming model

In the Philippines, smallholder farmers have become major timber producers. But the systems of timber production practiced have several limitations. In intercropping systems, the practice of severe branch and/or root pruning reduces tree-crop competition and increases annual crop yields, but is detrimental to tree growth and incompatible with commercial timber production. In even-aged woodlots, lack of regular income and poor tree growth, resulting from farmers’ reluctance to thin their plantations, are major constraints to adoption and profitable tree farming. In the municipality of Claveria, Misamis Oriental, the recent practice of planting trees on widely spaced (6–8 m) contour grass strips established for soil conservation suggests ways to improve the adoptability (i.e., profitability, feasibility and acceptability) of timber-based agroforestry systems. Assuming that financial benefits are the main objective of timber tree farmers, we develop a simple linear programming (LP) model for the optimal allocation of land to monocropping and tree intercropping that maximizes the net present value of an infinite number of rotations and satisfies farmers’ resource constraints and regular income requirements. The application of the LP model to an average farmer in Claveria showed that cumulative additions of widely spaced tree hedgerows provides higher returns to land, and reduce the risk of agroforestry adoption by spreading over the years labour and capital investment costs and the economic benefits accruing to farmers from trees. Therefore, incremental planting of widely spaced tree hedgerows can make farm forestry more adoptable and thus benefit a larger number of resource-constrained farmers in their evolution towards more diverse and productive agroforestry systems.     

Selection of native trees for intercropping with coffee in the Atlantic Rainforest biome

A challenge in establishing agroforestry systems is ensuring that farmers are interested in the tree species, and are aware of how to adequately manage these species. This challenge was tackled in the Atlantic Rainforest biome (Brazil), where a participatory trial with agroforestry coffee systems was carried out, followed by a participatory systematisation of the farmers experiences. Our objective was to identify the main tree species used by farmers as well as their criteria for selecting or rejecting tree species. Furthermore, we aimed to present a specific inventory of trees of the Leguminosae family. In order to collect the data, we reviewed the bibliography of the participatory trial, visited and interviewed the farmers and organised workshops with them. The main farmers’ criteria for selecting tree species were compatibility with coffee, amount of biomass, production and the labour needed for tree management. The farmers listed 85 tree species; we recorded 28 tree species of the Leguminosae family. Most trees were either native to the biome or exotic fruit trees. In order to design and manage complex agroforestry systems, family farmers need sufficient knowledge and autonomy, which can be reinforced when a participatory methodology is used for developing on-farm agroforestry systems. In the case presented, the farmers learned how to manage, reclaim and conserve their land. The diversification of production, especially with fruit, contributes to food security and to a low cost/benefit ratio of agroforestry systems. The investigated agroforestry systems showed potential to restore the degraded landscape of the Atlantic Rainforest biome.     

Economic potential of agroforestry for public recreational parks

The availability of public recreational facilities is being threatened by growing demands, limited supplies, and declining government funding. In response to these pressures, the economic potential of agroforestry for supplementing operating budgets of public recreational parks is examined in a case study park consisting of 324 hectares. Agroforestry enterprises native to the area were selected for development on 70 hectares of the site. Linear programming was used to determine the optimum combinations of 23 agroforestry regimes composed of the following activities: 1) conventional forestry planting, tree density of 1682 trees/hectare, 2) the selected agroforestry planting with hay, tree density of 1495 trees/hectare, 3) the selected agroforestry planting with grazing, 4) hay production, and 5) rental of pasture for grazing. The objective function of the study was to maximize the net present value of the study site subject to land, labor, capital, and minimum annual income constraints. The preferred optimal regime generated $1782 per hectare from an agroforestry planting configuration of 1495 trees/hectare with 75 percent hay, 25 percent grazing, and no annual income requirements. Minimum annual income requirements of $2400 and $4800 were feasible but suboptimal from a net present value criteria. The study found that agroforestry could be used to privatize selective activities of public recreational parks and thus enable public agencies to provide these facilities more effectively.     

Household tree holdings: A case study in Mutoko communal area, Zimbabwe

Tree holdings at homesteads and in homefields were investigated for two villages in Zimbabwe. Of the households, 90% owned at least one exotic tree. Trees were concentrated at homesteads and conserved indigenous trees tended to be edible fruit trees. Female heads of households (divorcees and widows) had fewer trees than households headed by men. Households with longer period of residence at a site had increased the proportion of indigenous fruit trees compared to non-fruit trees. Wealth status showed no relationship to tree holdings. The considerable tree planting and tree conservation activity around homesteads and in homefields has the effect of replacing non-fruit indigenous trees with exotic and indigenous fruit trees. Agroforestry research, extension and development should focus more on current practices, concentrate more on trees that farmers favour (such as fruit trees) and take into account differences among households. This revised version was published online in June 2006 with corrections to the Cover Date.     

Incorporating indigenous knowledge of fodder trees into small-scale silvopastoral systems in Jamaica

A study was conducted to identify and explore indigenous knowledge relating to fodder trees and silvopastoral management systems of small-scale farmers in seasonally dry areas of Jamaica. The objectives of the study were to: 1) explore farmers indigenous knowledge relating to fodder trees and silvopastoral management systems in a subtropical dry climate; 2) examine pastoral land-use systems and technologies in current use; and 3) seek to integrate this information into silvopastoral tree fodder systems. Data were gathered via observation and semistructured interviewing. A snowball sampling strategy was used to purposively select all small-scale farmers who had cattle in the Green Park valley for interview.Of forty farmers interviewed, 37 males (92.5%) and 3 females (7.5%) were primary caretakers of cattle. Twenty-seven of 40 farmers (68%) raised cattle to generate income. During extended droughts farmers are forced to look for alternatives to desiccated, overgrazed pasture grasses, including: 1) local travel to harvest sugar cane tops and to cut Guinea grass (Panicum maximum); 2) purchase of bag feed; and 3) harvest and use of tree fodder. Preferred fodder trees were identified as Bacedar (Guazama ulmifolia), Guango (Albizia saman), Breadnut (Brosimum alicastrum) and Quickstick (Gliricidia sepium).Recommended silvopastoral management systems include fodder hedgerows, three strata forage systems, and living fences. In addition, production of indigenous fodder tree species, introducing improved tree fodder species, and planting improved pasture grasses concurrent with cash trees is suggested.     

Research methods for multistrata agroforestry systems with coffee and cacao: recommendations from two decades of research at CATIE

This paper reviews the research themes and methodologies used by CATIE in agroforestry research with shade trees over coffee (Coffea arabica) and cacao (Theobroma cacao) during the past 20 years. Initially research focused on characterization and production studies (of crop and timber including border areas) of traditional systems using temporary and permanent sample plots on private farms. The assessment area of traditional shade-coffee (or cacao) systems should be the whole plot, including the border areas, and not some subjectively selected central area which supposedly represents unit area productivity. Uncontrolled crop, tree, and management heterogeneity limited extrapolation of early on-farm research results to other farmers' fields. Replicated case studies of best bet technologies (traditional or experimental) on different farms are often preferable to the use of formal experimental designs. On-station research included the use of systematic spacing designs to test extreme shade tree density treatments of coffee. Most nutrient cycling studies were also carried out on-station, using service and timber shade species over coffee and cacao to evaluate the ability of these agroforestry systems to maintain nutrient reserves and diversify production. Plot size (even 36 × 36 m) was limiting for long term research because of inter-plot interference, both below- and above ground, when using fast growing, tall timber trees as shade. These experiences suggest a minimum plot size of 2,500 m². Individual tree designs and tree-crop interface studies (e.g. regression analysis of data taken along transects) are promising experimental/sampling approaches that need further development. The principal research thrusts proposed for the next five years are bio-physical process research on coffee responses to shade and competition with trees (growth, carbon allocation, phenology, disease-pest tolerance, yields and coffee quality effects) and socioeconomic analyses of both traditional and new or improved shade – coffee combinations vs. monocultures. This revised version was published online in June 2006 with corrections to the Cover Date.     

Growth of widely spaced trees. A case study from young agroforestry plantations in France

Pessimistic forecasts often suggest that widely spaced trees enjoying free growth (no competition with other trees) will fail to provide high quality timber. This challenges the temperate agroforestry practice of planting widely spaced trees to produce high quality timber. We analyse tree growth data from recent temperate agroforestry plantations aged three to eight years, featuring low tree plantation densities (50 to 400 stems ha−1), the association of trees with intercrops (silvoarable systems) or animals (silvopastoral systems), and the use of plastic shelter tubes to protect trees (1.2 to 2.5 m high) and avoid damage by cattle or sheep in pastures or facilitate maintenance in silvoarable systems. The plantations are located in climates ranging from Mediterranean, dry central temperate plains, cold and wet central uplands to mild oceanic areas. Some plantations included a forestry control (high density of plantation, no tree shelter, no intercropping nor grazing). Trees were evaluated for height and diameter growth and stem form (straightness and absence of knots). Trees in most agroforestry plots grew satisfactorily, often faster than in forestry control plots. In some experimental plots, average annual height increments as high as 1 m and diameter increments as high as 1.5 cm were observed. Few agroforestry plantations were unsuccessful, and the reasons for the failures are discussed: animal damage in silvopastoral plots, but also a wrong choice of tree species unsuitable for local soil and climate characteristics. From these early results we can formulate some guidelines for designing future agroforestry plantations in temperate climates, concerning tree density, use of tree shelters and care required for widely spaced trees. This revised version was published online in June 2006 with corrections to the Cover Date.     

Indigenous Agroforestry Systems in Amazonia: From Prehistory to Today

Understanding the historical development of indigenous systems will provide valuable information for the design of ecologically desirable agroforestry production systems. Such studies have been relatively few, especially in Amazonia. The agroforestry systems in Amazonia follow a trail that begins with the arrival of the first hunter-gatherers in prehistoric times, followed by the domestication of plants for agriculture, the development of complex societies rich in material culture, the decimation of these societies by European diseases, warfare, and slavery, the introduction of exotic species, and finally, the present-day scenario of widespread deforestation, in which agroforestry is ascribed a potential role as an alternative land use. Despite the upheavals which occurred in colonial times, greatly reducing the population of native tribes, a review of anthropological and ethnobiological literature from recent decades indicates that a great variety of indigenous agroforestry practices still exist, ranging from deliberate planting of trees in homegardens and fields to the management of volunteer seedlings of both cultivated and wild species. These practices result in various configurations of agroforestry systems, such as homegardens, tree/crop combinations in fields, orchards of mixed fruit trees, and enriched fallows. Together they constitute a stock of knowledge developed over millenia, and represent technologies that evolved along with the domestication of native forest species and their incorporation into food production systems. This knowledge is the basis for the principal agroforestry practice employed by farmers in Amazonia today, the homegarden, and has potential to contribute to the development of other agroforestry systems.     

Role of woody perennials in animal agroforestry

Two main roles are identified in the review: the productive one, where woody perennials yield a material output (fuel, fodder, etc.), and the ‘service’ type, with no tangible product (shelter, nutrient recycling, etc.). In their productive role trees and shrubs may supply fodder in browsing systems, or industrial material, wood products and food in forest and plantation grazing systems. Service roles, rarely divorced from productive ones, arise mainly from relationships between woody perennials and the herbaceous vegetation growing in their vicinity. As a fodder source, the relatively low productivity and palatability of high protein content foliage from most woody perennials would indicate a supplementary role, particulary during dry seasons in arid and semiarid zones. In these type of lands pod-bearing trees seem to have a greater potential for improving fodder production in silvopastoral systems. The negative effect of trees on pasture production in forest and plantation grazing is compensated by their contribution to the system through other products. Available data would support the potential of certain species of woody perennials to foster pasture growing underneath, mainly through soil enrichment. Windbreaks can also indirectly benefit pasture growth, by decreasing water loss from the soil. It is postulated that research efforts in animal agroforestry should be focused on woody perennials for browsing systems, particularly on pod-bearing trees having beneficial effects on the herbaceous layer growing underneath.     

Concentrations of nitrate in soil water following herbicide treatment of tree planting positions in an upland agroforestry system

Concentrations of nitrate have been measured in soil water samples collected during the first year of an agroforestry trial at an upland site in Wales. Nitrate concentrations were higher in water samples collected from herbicide-treated areas around trees than from undisturbed pasture between the trees. These differences were statistically significant fo samples collected during the summer but not for those from the main winter leaching period. The enhanced nitrate concentrations that were measured beneath the tree planting positions may have implications for the nutrition of the trees but, at the planting densities included in the trial (100 and 400 trees/ha), are estimated to represent only a small increase in the nitrate content of water draining from the agroforestry area as a whole, relative to that from unplanted pasture. There was some evidence that preferential deposition of urine, but not of dung, contributed to the increased nitrate contents in the soil around the planting positions.     

Agroforestry potential of Dacryodes edulis in the oil palm-cassava belt of southeastern Nigeria

Between June 1993 and June 1994, 112 farmers in the oil palm (Elaeis guineensis)-cassava (Manihot esclentus) belt of southeastern Nigeria were interviewed to determine the status and agroforestry potential of Dacryodes edulis. Between 50% and 100% of respondents in different states within the belt owned D. edulis trees. On average, a farmer owned 9.3 trees, the largest number being 16, by farmers in Imo State. Twenty percent of farmers in the system rated D. edulis their best farm tree. It was present in all the farm niches: homegardens (51.4%), tree crop plots (20.7%) food crop plots (11.4%), secondary forest/fallow (14.2%) and virgin forest (2.5%). The tree is planted primarily for home consumption and sale to generate cash. At the current densities, on-farm D. edulis trees generally did not decrease yield of companion crops or trees. Except for ring weeding around the stem, D. edulis trees received little or no management attention. More than 50% of the trees produced 33 to 50 kg of fruit tree⁻¹ annually. This is valued at US $0.4 to 0.8 kg⁻¹. Farmers were willing to plant more D. edulis trees provided trees with traits such as less height for easy harvesting of fruits, larger fruit, more fruits, sweeter fruits and year round production of fruits were available. Possible agroforestry technologies into which D. edulis may fit include live fences, scattered trees in food crop fields, shade trees in tree crop plots and contour bund or hedgerow planting. Research is required to determine best tree accessions, canopy management strategies, optimum tree population and improved methods on post- harvest handling of fruits. This revised version was published online in June 2006 with corrections to the Cover Date.