Temperate agroforestry research: considering multifunctional woody polycultures and the design of long-term field trials

The many benefits of agroforestry are well-documented, from ecological functions such as biodiversity conservation and water quality improvement, to cultural functions including aesthetic value. In North American agroforestry, however, little emphasis has been placed on production capacity of the woody plants themselves, taking into account their ability to transform portions of the landscape from annual monoculture systems to diversified perennial systems capable of producing fruits, nuts, and timber products. In this paper, we introduce the concept of multifunctional woody polycultures (MWPs) and consider the design of long-term experimental trials for supporting research on agroforestry emphasizing tree crops. Critical aspects of long-term agroforestry experiments are summarized, and two existing well-documented research sites are presented as case studies. A new long-term agroforestry trial at the University of Illinois, “Agroforestry for Food,” is introduced as an experiment designed to test the performance of increasingly complex woody plant combinations in an alley cropping system with productive tree crops. This trial intends to address important themes of food security, climate change, multifunctionality, and applied solutions. The challenges of establishing, maintaining, and funding long-term agroforestry research trials are discussed.     

An approach to developing methodologies for evaluating agroforestry systems in India

India has a long tradition of agroforestry and many different types of indigenous agroforestry systems can be found in different parts of the country. Most of these systems are, however, very location-specific, and information on them is mostly anecdotal. Therefore, their benefits have remained vastly underexploited. The situation is now slowly but steadily changing. It has now been well recognized that agroforestry can address some of the major land-use problems of rainfed farming systems, and that a great deal can be accomplished by improving the indigenous systems. However, agroforestry research is still in its infancy; most of the on-going efforts are of the “WHAT” type dealing with component and system management, with too little attention being paid to the “WHY” (reasons for the observed behavior) and the “HOW” (processes involved) of the results. Therefore, most of the research results obtained from such efforts are also largely location-specific. In order to improve the efficiency of indigenous agroforestry systems, as well as to assess the performance of improved technologies, we need to have a systematic procedure to evaluate such systems. Since productivity, sustainability and social acceptability are the key attributes of all agroforestry systems, evaluation procedures should encompass all these criteria. But the precise criteria for such evaluations have still not been fully developed. A broad evaluation of the indigenous agroforestry systems and current research efforts in India shows that the thrusts of agroforestry efforts are different in different agro-ecological regions depending on the region's characteristic land-use constraints. Therefore it should be possible to develop an evaluation matrix of agro-ecological regions versus agroforestry potentials and attributes. Such a matrix could be a framework for evaluating agroforestry systems, as well as a guide for the type of research and nature of data that will need to be generated from agroforestry projects. The matrix with necessary adjustments can be made use of for agroforestry systems evaluation within relatively smaller areas such as sub-regions to larger areas such as states, or zones consisting of several states. The results of such evaluations can be thses for appropriate extension recommendations for that specific area or region.     

Agroforestry adoption in the Calakmul Biosphere Reserve,Campeche, Mexico

Since farmers engage in a complex, dynamic process of learning-by-doing, evaluating economic incentives, and assessing risks in deciding whether to adopt agroforestry systems, a multi-pronged research approach is required for a complete analysis of adoption potential and to develop effective technological and institutional interventions. A case study is presented for using multiple approaches to analyse the potential for reforestation and improving livelihoods of small farmers through the adoption of agroforestry systems in the Calakmul Biosphere Reserve in Campeche, Mexico. Specifically, the results from a participatory research project are combined with revealed preference analysis of a household survey to analyse past adoption decisions and preferences, identify limitations, test and evaluate alternatives, and evaluate methods for risk reduction. The participatory research trials suggest that continuous intercropping and line cleaning are equally effective for tree growth, while continuous cropping during the first years offers the additional advantage of early returns to investments through crop production. Farmer participation in the research process, planning of production systems, and annual evaluations, assisted farmers and researchers in identifying limitations, testing and evaluating alternatives, and improving the viability and sustainability of systems. The revealed preference analysis provides insights as to which households are most likely to initially adopt agroforestry systems developed through the participatory research trials. In general, households that originated from the Yucatan Peninsula with more education, more experience both in age of the head of household and technical and project experience, higher incomes, and those that had cleared more forestland were more likely to have experimented with agroforestry systems in the past.     

Multipurpose leguminous trees and shrubs for agroforestry

These are various ways in which farmers deliberately incorporate trees and shrubs on farm production fields. Many of the species so incorporated are legumes. The role of such woody perennials in agroforestry systems can be productive and/or protective. Legumes offer by far the maximum range of choice of woody species for agroforestry in terms of their economic uses as well as ecological adaptibility. In addition to the several leguminous woody species that are well known in agroforestry, there are many more whose potentials have not yet been fully understood. An evaluation is presented of the agroforestry potentials of a few leguminous species from the point of view of their growth characteristics, ecological adaptability, combining ability with other species and uses/functions. The science of agroforestry is still in its infancy. There exists no research data on the various management aspects of these potentially promising group of plants. ICRAF, in its capacity as an international research council, has assembled several multipurpose leguminous trees and shrubs of agroforestry potential at the Council's recently-established Field Station in Machakos, Kenya, primarily for demonstration and training purposes. Initial results from these trials are presented in the paper.Adapted from a paper presented at the International Symposium on Nitrogen Fixing trees in the Tropics, 19–24 September, 1983 Rio-de-Janeiro, Brazil.     

Comparison of the erosion control potential of agroforestry systems in the Himalayan region

The great erosion control potential of agroforestry systems is generally recognized. However, insufficient data are available to be able to give absolute quantitative values for the erosion control potential of specific agroforestry systems or to compare their potential. To obtain such quantitative erosion data, long-term standard erosion measurements should be done in specific agroforestry systems. Such measurements may become very costly because the data need to be collected in a wide range of agroforestry systems on different sites over a long time. A further constraint is the reliability of such information: erosion figures may not be comparable because of discrepancy between the scale of measurement and the scale of the agroforestry system and the occurrence of different kinds of erosion. The methodology presented here enables a quick comparative estimation of the erosion (surface erosion, gully erosion and mass movement) control potential of different agroforestry systems. The erosion control value of agroforestry systems is related to their protective functions: the cover, barrier and soil reinforcement functions. The methodology involves identifying which features influence these different functions within a specific agroforestry system and subsequently evaluating the efficacy. The applicability of this methodology is demonstated with examples from various agroforestry systems in the Himalayan region.     

A spatial database approach for estimating areas suitable for agroforestry in subSaharan Africa: aggregation and use of agroforestry case studies

The growing awareness of the importance and potential of agroforestry has resulted in an invaluable proliferation of site specific case studies. These presently exist in the necessary quantity and quality so as to facilitate their aggregate utilization in larger-scale research and application inquiry. We report here an approach for aggregating and using agroforestry case studies for agroforestry-related research at scales larger than the local site. The work presented here describes how ICRAF's agroforestry database — the primary source of case studies — can be used in combination with satellite imagery, and ancillary information, via matrix operations and a geographic information system, to produce a GIS-based agroforestry research tool for subSaharan Africa. This tool is used in a large-scale and preliminary way, to estimate the areas to which appropriate agroforestry systems in Africa might be extended.     

Expanding opportunities for agroforestry education in the U.S. and Canadian universities

A telephone survey of 39 U.S. and Canadian University forestry schools accredited with the Society of American Foresters, conducted in November 1988, showed that 25 had courses in tropical and international forestry, and 14 university faculties had been conducting research in agroforestry. Field-oriented training in agroforestry is also offered in North America, especially for voluntary and relief organization personnel. Many of the agroforestry courses have been established recently in response to desires of students with international interests and/or experience. Most of such courses are integrated programs, initiated by forestry faculty, and most of these are seminars or colloquia incorporating the experience of both faculty and students with focus on systems and issues rather than technical proceses. Ideas for agroforestry course content offered by North American forestry faculty include: integration of social and technical aspects of agroforestry and social forestry, involvement of multidisciplinary teams, focus on managing marginal, lands and consideration of the importance of agroforestry systems in North America and other temperate zones.     

Agroforestry education and training: a contemporary view

Most of the existing agroforestry courses have arisen opportunistically and tend to be based on the form that agroforestry takes, rather than on the way agroforestry practices function. Yet agroforestry research is beginning to supply ideas and information about the core issues (e.g., how woody and non-woody intercrops behave in terms of environmental resource capture, and how this can be influenced by the biology of the plant components and management). Similarly, recent socioeconomic research on agroforestry issues reveals dynamic systems of resource access, use, and control at various levels of human organization over time. It is true also that, because they were undertaken with different objectives in mind, the concepts derived from many decades of research in ecology, agriculture, and forestry still need to be reshaped for agroforestry situations. Likewise, socioeconomic content needs to move towards teaching the dynamics of decision-making, innovation, and change rather than describing static situations. This reshaping process itself offers exciting possibilities for educators who, thereby, could influence the course of research.These issues are briefly discussed in relation to the integration and development of research and teaching, and the needs of students and agroforestry professionals for educational and training courses. A draft proposal for the future of agroforestry at Cornell University is also outlined as a model for implementing such an approach.     

Advances in European agroforestry: results from the AGFORWARD project

In global terms, European farms produce high yields of safe and high quality food but this depends on the use of many off-farm inputs and the associated greenhouse gas emissions, loss of soil nutrients and other negative environmental impacts incur substantial societal costs. Farmers in the European Union receive support through a Common Agricultural Policy (CAP) that comprises direct payments to farmers (Pillar I) and payments related to rural development measures (Pillar II). This paper examines the ways in which agroforestry can support European agriculture and rural development drawing on the conclusions of 23 papers presented in this Special Issue of Agroforestry Systems which have been produced during a 4-year research project called AGFORWARD. The project had the goal of promoting agroforestry in Europe and focused on four types of agroforestry: (1) existing systems of high nature and cultural value, and agroforestry for (2) high value tree, (3) arable, and (4) livestock systems. The project has advanced our understanding of the extent of agroforestry in Europe and of farmers’ perceptions of agroforestry, including the reasons for adoption or non-adoption. A participatory approach was used with over 40 stakeholder groups across Europe to test selected agroforestry innovations through field trials and experiments. Innovations included improved grazing management in agroforestry systems of high nature and cultural value and the introduction of nitrogen fixing plants in high value timber plantations and olive groves. Other innovations included shelter benefits for arable crops, and disease-control, nutrient-retention, and food diversification benefits from integrating trees in livestock enterprises. Biophysical and economic models have also been developed to predict the effect of different agroforestry designs on crop and tree production, and on carbon sequestration, nutrient loss and ecosystems services in general. These models help us to quantify the potential environmental benefits of agroforestry, relative to agriculture without trees. In view of the substantial area of European agroforestry and its wider societal and environmental benefits, the final policy papers in this Special Issue argue that agroforestry should play a more significant role in future versions of the CAP than it does at present.     

Agroforestry and forestry-related practices in the Midwestern United States

A survey, conducted in 1990–1991 on agroforestry and forestry-related systems in eight Midwestern states, showed that three traditional and three nontraditional agroforestry systems are practiced in the region. Of 46 traditional systems reported, most common was agrisilviculture (28), then silvipasture (12) and agrisilvipasture (6). These systems often involved corn, soybeans, and hay planted with tree species for nut, timber, or Christmas tree production, and cattle. Non-traditional agroforestry systems were field windbreaks/shelterbelts (29), treeshrub intercropping systems (21), and boundary plantings (11). These systems involved a variety of northern hardwood species evergreens, and shrubs. There was also a preponderance of specialized systems (97) of growing trees with the production of mushrooms, nuts, syrup, wildlife, and other nonwood products. The survey is exploratory in nature and, although the results may not represent a complete count of people involved with agroforestry in the region, the numbers reported may indicate where a practice may be prevalent. The results reflect the fact that much work still needs to be done by agroforesters in this region. They also provide some basis for further research on more suitable systems, and for identifying other researchable questions on agroforestry for the region. The methodology also made possible a bigger nucleus for networking of agroforesters and other interested people in the Midwest. Finally, although not normally considered as agroforestry, the significance of the other specialized systems reported in this survey is that they offer varied ways of connecting forestry with other activities in a largely agricultural landscape, and that they may even be seen as opportunities for easier transition into agroforestry.     

Soil productivity,soil conservation and land evaluation

ICRAF's main contributions to research related to soils have been a symposium, Soils Research in Agroforestry; a review of soil productivity aspects of agroforestry; a further review of the potential of agroforestry for soil conservation, covering both erosion control and maintenance of fertility; the construction of a computerized model to predict soil changes under agroforestry systems; and a handbook of practical methods of agroforestry for soil and water conservation in dryland Africa. In research on land evaluation, an environmental data base has been established, leading to a capacity to obtain information, for environmental conditions similar to those of a given site or area, on publications, multipurpose trees, crops, existing agroforestry systems and current experimental work. Land evaluation for agroforestry cannot be achieved merely by synthesis of methods from agriculture and forestry, but will require more data on the performance of agroforestry land utilization types. Recognition of problems of environmental degradation has become an integral part of planning for agroforestry research. By means of a partial synthesis between land evaluation and diagnosis and design, a procedure of site selection for agroforestry research and development has been established.Principal Scientist, ICRAF     

Alternate cycle agroforestry

Agroforestry research and design has heavily favored intergrated production of annuals and perennials, that is production of tree crops on the same parcel of land and at the same time as production of food crop annuals. For areas having high population densities and intensive modes of agricultural production, integral agroforestry may be appropriate, but for areas of sparse population where extensive agriculture is practiced or marginal hill lands, alternate cycle agroforestry may prove more suitable. Alternate cycle agroforestry, in the form of modified forest swidden systems, is discussed and compared to integral agroforestry systems. Advantages and disadvantages of each system are discussed relative to their use on marginal hill and forest lands.The author wishes to thank N.T. Vergara, L.S. Hamilton, A.T. Rambo and K.F.Wiersum at the Environment and Policy Institute of the East-West Center for their comments.     

Agroforestry policy issues and research directions in the US and less developed countries: insights and challenges from recent experience

Efforts to improve the performance of agroforestry systems, and to expand the land area and number of people able to benefit from this integrative approach to agriculture and natural resource management, are constrained throughout the world by non-supportive land use policies. A growing sense of urgency that policy change is needed to enable agroforestry to flourish has contributed during the past two years to an unprecedented level of agroforestry policy assessment and planning activity.In the US, agroforestry has emerged from academia, where it has incubated since the mid-1980s, into the professional resource management arena. A multi-organizational agroforestry evaluation process has driven national policy and program formation to the forefront of the agenda of the agroforestry community, as it seeks to influence the 1995 Farm Bill. Internationally, the Consultative Group on International Agricultural Research and collaborators fostered a sequence of policy issue identification activities as a basis for setting strategic research priorities for forestry and agroforestry.Following a brief review of forces driving agroforestry development in industrialized and less developed countries, the paper highlights recent policy assessment initiatives in each sphere. Observations on the issues driving and the priorities emerging from these processes are offered, to lend perspective to the critical challenges facing the agroforestry policy research community. An explanation for pervasive constraints and inconsistencies in policy effectiveness is then explored, from which a promising approach to research intervention is forwarded.It is argued that social scientists might influence agroforestry policy most favorably at this critical juncture, as perceptions of inter-dependence increase among different stakeholders in the policy system, by employing interventionist, actor-oriented perspectives and participatory methods to facilitate policy innovation and evaluation. The approach is consistent with participatory technology design processes that earlier helped to establish agroforestry as a prototype for sustainable development.     

Resource development for professional education and training in agroforestry

The development of agroforestry education and training is hampered by a shortage of information on agroforestry practices and systems and by institutional constraints which limit effective transfer of existing knowledge. Generation of knowledge through research and the effective sharing of information on agroforestry are critical to the building of a solid resource base for agroforestry education. Networks of individuals and institutions can accelerate the development of resources for agroforestry education. Primary activities of an agroforestry network would include the development and dissemination of training materials on agroforestry, curriculum development and training of teaching staff. Critical considerations for the successful establishment and operation of a network include: (1) focusing the network on a problem and identifying sufficient interest, (2) personnel requirements such as an institution with a strong commitment, and (3) other resource requirements such as funds for network meetings, publications and research.     

Assessing agroforestry adoption potential utilising market segmentation: A case study in Pennsylvania

In the United States, agroforestry adoption has lagged behind progress in agroforestry systems research. This study sought to facilitate the communication of landowner land management objectives, values, knowledge and perceptions of the barriers and benefits to agroforestry through applied social marketing research methods and market segmentation analysis. A mail survey instrument was sent to 250 members of the Pennsylvania Association of Sustainable Agriculture (PASA) and 250 members of Woodland Owner Associations (WOA). Current management objectives and production strategies, agroforestry awareness, agroforestry interest, and perceptions regarding the benefits and obstacles to agroforestry adoption were gauged. Market segmentation was performed with a two-step cluster analysis to produce four agroforestry adoption potential models: Timber-Related Practices, Livestock-Related Practices, Specialty Crop-Related Practices, and Non-Adopters. The analyses showed that agroforestry practices could satisfy specific land management objectives within diverse populations. The method effectively identified similarities in agroforestry adoption scenarios. Market segmentation could be utilised as a social marketing tool to guide future policy development, scientific research, and the efficacy and relevance of future agroforestry research and outreach programs. The next step in program development should include the creation of a statewide multidisciplinary team comprised of university, non-profit association and landowner representation, to develop agroforestry applications relevant to each cluster and promote the practices through landowner-led on-farm demonstrations and workshops.     

Growth and yield of coffee plants in agroforestry and monoculture systems in Minas Gerais, Brazil

This research compared coffee plants (Coffea arabica L.) grown in an agroforestry and monoculture systems. Data were collected during two years, on vegetative growth, reproductive development, nutritional status and yield of coffee, besides monitoring air temperature and the tree growth. All trees in agroforestry system increased in growth, resulting in a reduction in the magnitude of the diurnal temperature variation and also maximum temperature. Coffee plants in agroforestry system had less branch growth and leaf production, more persistent and larger leaves, and presented earlier flowering, with a smaller number of productive nodes and flower buds, leading to smaller berry yield than plants in monoculture system. In both systems, the coffee plants showed adequate leaf nutrient levels, except for P and K. The yield of 2443 kg ha^-1 of coffee from the monoculture was greater than 515 kg ha^-1 of coffee from the agroforestry system.     

Increasing Tree Cover in Degrading Landscapes: ‘Integration’ and ‘Intensification’ of Smallholder Forest Culture in the Alutilla Valley,Matiranga, Bangladesh

Research was conducted in Alutilla Valley in eastern Bangladesh to identify the nature of existing agroforestry systems and to identify potential agroforestry models that could ameliorate currently degrading forest resources Data were collected through farmer participatory research and a structured quarterly survey in two villages. Qualitative and supplementary quantitative analysis methods were used to assess the financial potential of agroforestry systems. Various patterns of agroforestry exist in the study site, but all have two common principles, namely ‘integration with agriculture’ and ‘multi-functionality’. Two agroforestry models suitable for adoption by farmers have been identified. Multi-strata agroforestry, based on a fruit and timber tree canopy with vegetables and tuber species in the understorey, can be practiced in the shifting cultivation fields near settlements. Fruit and timber tree-based conservation agroforestry is well suited to manage large-scale biologically depleted landscapes. Both systems yield early financial returns, facilitating the change from shifting cultivation to multi-strata agroforestry or fruit and tree-based conservation agroforestry.     

Agroforestry education and training programs: an overview

Agroforestry has been incorporated in education and training programs at an unprecedented level since 1982. A survey of educational institutions conducted by ICRAF in 1987 revealed that agroforestry is found as an option for specialization in undergraduate as well as in postgraduate M.Sc, diploma programs in forestry, agriculture, natural resources, and others. Courses and special seminars in agroforestry are organized in degree programs. Full undergraduate and postgraduate programs in agroforestry are being formulated and implementation started in quite a few universities, and many students are choosing agroforestry-oriented research projects for their dissertations. A good setting for higher degree training in agroforestry requires, however, staffing from combined faculties of at least agriculture, animal science and forestry; faculty commitment to a farming systems approach; and inter-departmental cooperation in teaching and research. It was difficult to asses whether these and other elements are present in existing programs where agroforestry has been incorporated. Emerging trends indicate that traditional forestry programs are broadening the scope of the discipline (from forests to integrated land-use systems) while agriculturists are recognizing that trees play important roles as soil improvers and protectors, fodder, food, fuel and other domestic and commercial purposes. New institutional structures are evolving to allow for educational programs with coursework and research projects spanning many disciplines. Nondegree training in agroforestry has seen an upsurge of activities equal, if not larger, to that in education. Attempts are being made by different institutions worldwide to inventory training opportunities; still the collection and dissemination of information is difficult. Efforts are needed at the international, regional, and national levels, to address training issues that if addressed collectively can improve the quality and effectiveness of human resource development efforts. ICRAF's approach to promote agroforestry research through education and training is an example of an action program currently under application.