Toward Sustainability A Plan for Collaborative Research on Agriculture and Natural Resource Management (1991) / Chapter Skim
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Appendix D: The Agroecosystems
Appendix D: The Agroecosystems
Pages 91-104
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From page 91... ...
The commodity focus has enabled researchers to build interdisciplinary teams and methodologies, to strengthen institutional structures around the world, and to bring local experience and needs to the attention of the global research community. Not incidentally, commodity-centered programs have also yielded important insights into a variety of agronomic considerations germplasm conservation, nitrogen fixation, rotational effects, and pest population dynamics, to cite only a few examples that are critical to sustainable agriculture in their particular agroecosystems.
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From page 92... ...
It will serve as a tool to organize ideas, hypotheses, methods, and results, and ultimately to gain insight into principles of sustainability. The resource base and the human population that relies on it are at greatest risk in several primary global agroecosystems: the humid tropics, semiarid range and Savannah, hill lands, and input-intensive agroecosystems.
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From page 93... ...
Once cleared, the soils are easily eroded, their residual nutrients leached, and their role in the hydrological cycle disrupted. Soil acidity and nutrient deficiency are common chemical constraints to crop production in the humid tropics under any circumstances, and addressing those problems is key to the development of sustainable methods that can ease the pressure on the remaining rain forests, restore already degraded forestland through a variety of agroforestry strategies, and allow for more efficient and intensive cropping of developed land.
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From page 94... ...
Although the industrial nations bear most of the responsibility for aggregate atmospheric carbon additions, the destruction of forests is particularly significant because important carbon sinks tropical forest biomass and soils are now becoming carbon sources. The models of greenhouse dynamics remain contentious, but they suggest that some of the areas of greatest agricultural production in the United States, especially California, Florida, and parts of the Midwest, are vulnerable to climate modifications.
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From page 95... ...
The development of ecologically, socially, and economically viable forms of land use in the humid tropics will require a strategy that builds on their characteristic diversity of the humid tropics and mimics their complex ecological processes. Research on the humid tropics is expanding as attention is drawn to their status, their role in the global environmental system, and the fate of the people who depend on them for their livelihood.
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From page 96... ...
Overgrazing has increased in frequency and extent, and in some areas it has triggered the positive feedbacks that lead to environmental degradation in grassland ecosystems: decreased vegetative cover, invasion by unpalatable species, declining livestock quality, excessive wind and water erosion, soil erosion and degradation, increased susceptibility to the effects of drought, and ultimately desertification. Sustainability in semiarid regions will depend first and foremost on the recognition of the inherent fragility of semi
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From page 97... ...
Sustainable approaches are badly needed because population growth has put serious pressure on the fragile natural resource base. Agricultural development in sub-Saharan Africa, as in most semiarid regions, is constrained by readily identifiable factors: water availability; soil nutrient availability, erosion, physical properties, and organic matter; the institutional and human resource base; and the policies necessary to manage soil and water resources.
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From page 98... ...
Proposals for research in this agroecosystem should demonstrate the following capabilities: innovative approaches to system modeling that are realistic, workable, and applicable; · integrated research experience, previous commitment to work in the semiarid zone, commitment of university cost-sharing resources, continuity of staffing, and experience in systems research and management; · an agroecological research framework that gives full attention to biotic, abiotic, and socioeconomic factors, including analysis of indigenous natural resource management; and · complementarily and interaction with nongovernmental and private voluntary organizations, other CRSPs, and other international agricultural research organizations. HILL LANDS Mountain agroecosystems constitute approximately 25 percent of the total land surface of the earth, and they contain at least 10 percent of the total
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From page 99... ...
It is difficult to generalize about the mountain agroecosystem, because it incorporates elements of all other ecosystems from the humid tropic ecosystems on the eastern slopes of the Andes of South America to the arid and semiarid ecosystems of the western Himalaya in South Asia. Above all, the mountain agroecosystem must be viewed as a composite of ecosystems: a three-dimensional environmental mosaic defined by factors of altitude, slope, and aspect, and characterized by agricultural problems encountered across the full spectrum of agroecosystems.
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From page 100... ...
Development and testing of the model should begin with the most fundamental, and potentially unstable, characteristics of the mountain agroecosystem the soil and water "life support" resource base—and should eventually incorporate all factors, including the socioeconomic and cultural. Once a reliable model is available, researchers can develop new techniques to evaluate factors relevant to sustainability in mountain agroecosystems, including the suitability of landscape, ecosystem, or socioeconomic units for various management options; mitigation and control methodologies; activity options and alternative agricultural technologies; comparative advantages, in biophysical and socioeconomic terms, of available methods; and the economic, production, and environmental impacts of potential interventions.
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From page 101... ...
The top priority for research on input-intensive systems should be to assess the interactions and implications of efforts to attain higher average yields, especially as they affect long-term productivity of soil and water resources and environmental quality, both on-farm and within the region. To this end, the relationship between attainable yield goals and yield instability may be of great importance from the perspective of food security and, hence, warrant special focus in research proposals.
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From page 102... ...
In meeting these general criteria, each proposal should include the following components: · a description of the distinct area and agroecosystem in which the research will be conducted and the collaborative efforts that will be undertaken with local organizations and institutions; · an explanation of the local, regional, and (if appropriate) global significance of the type of cropping systems chosen for analysis; a discussion, with a high degree of specificity, of the biological, ecological, physical, social, and economic conditions necessary for sustainability that the proposed research will help elucidate; and an evaluation of the importance of socioeconomic, infrastructure, land tenure, and policy considerations in the evolution of cropping practices that may prove unsustainable, and in the adoption of improved production methods that would evolve from successful completion of the proposed research project.
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From page 103... ...
; by environmental concerns (especially water quality issues involving soil erosion, siltation, and the runoff of pollutants, fertilizers, and pesticides) ; and by the prospect of global climate change and its attendant impact on sea levels and biodiversity.
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From page 104... ...
Sustainability is itself a relatively new term, and researchers have only begun to define the structure of the science that describes it. At this point, one can say that there are fairly well-developed principles governing agroecological systems that, if violated, make systems unsustainable; that those principles can be elaborated; that once elaborated they can be converted into hypotheses appropriate to a particular agroclimatic region; that research can be designed to validate, accept, reject, modify, or develop further those hypotheses by conducting investigations and on-farm tests in the relevant regions; and that the investigations and tests can then be evaluated and interpreted in the broader context that a systems perspective provides.
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