Conclusions
I have demonstrated that application of some knowledge, logic, planning, sensitivity, and compromise could allow us to continue using most rangelands for traditional values as well as provide for preservation and even enhancement of biodiversity. Because of their rarity, desirability to research, and in guiding management, most areas that have escaped livestock use thus far should probably be protected. This will provide maximum landscape diversity, reference areas for monitoring and basic...
Applications
Conventional agriculture creates a special ecosystem by mixing the topsoil (and compacting it) through tillage, removing plant canopies that protect the soil, adding fertilizers and biocides, and removing harvests. A more sustainable agriculture minimizes topsoil disturbance, reduces inputs, and substitutes organic for mineral fertilizers (Doran and Werner, 1990). Plowing in conventional agriculture incorporates crop residues into the soil profile to produce homogeneous soils that favor the...
Acknowledgment
This chapter has grown out of the authors' collaborations and conversations with a number of colleagues over the years. These colleagues have shaped our thinking and informed our views on genetic resources for agriculture. Among them are Mauricio Bellon, Cheryl Doss, Bob Evenson, Paul Heisey, Dominique Louette, Prabhu Pingali, Brian Wright, and members of the faculty workshop on biodiversity at Williams College. Wanda Collins offered detailed and useful comments on an earlier draft of this...
Beneficial Insects and Their Value
Parasitic and predatory insects occur within a wide range of insect groups, and at times, can be relatively abundant. Some common representatives include predatory carabid, coccinellid, and staphylinid beetles predatory bugs lacewings syrphid, chamaemyiid, and other predatory flies ants and parasitic wasps. Related to the beneficial insects are predatory mites and spiders. These different beneficials prey on and reduce phytophagous pest populations and, thus, promote higher standards of crop...
Approaches To Breeding
Approaches to crop improvement generally fall into one or two broadly defined systems Formal systems, in which modern science is brought to bear on crop improvement by institutions such as government plant-breeding stations, university departments, and private breeding companies, with the aim of producing cultivars for wide, often commercial, distribution to farmers. Informal systems, in which farmers and local communities, mainly in developing countries, breed and select cultivars primarily to...
Cultivation
Cultivation affects biogeochemical cycling by physically rearranging soil particles and changing pore size distribution, patterns of water and gas infiltration, and gas emission (Klute, 1982). Tillage disrupts soil aggregates, closes soil cracks and pores, and promotes drying of the surface soil. Soil fauna become sparse in top layers of cultivated soil because moisture content fluctuates widely and the original pore space network in this layer is destroyed. These physical alterations of the...
Introduction
Researchers have long been aware of the importance of genetic diversity in agroecosystems. At one level, diversity can provide ecosystem services to agriculture for example, beneficial insects and soil organisms can contribute to crop health and reduce the need for agricultural chemicals.1 At another level, plant breeders and other scientists rely on genetic resources for crop improvement and other technological advances. Traditional plant breeding and newer biotechnologies make it possible to...
Guidelines For A New Style Of Rangeland Management Sensitive To Biodiversity
Recent happenings in the Interior Columbia Basin are symptomatic of the start of a new era in land management. When human populations were lower and demands on resources were less, we could encourage development without much concern for other species or equity to the future. It is becoming obvious now that more consideration for present neighbors and future generations must be consciously given. Environmental impacts no longer have only local consequences. Biodiversity can be viewed as a...
Info
Piper, Farming in Nature's Image, Island Press, Washington, D.C., 1992. With permission. Adapted from J. D. Soule and J. K. Piper, Farming in Nature's Image, Island Press, Washington, D.C., 1992. With permission. with time, (3) restoration of original soil structure and function following disturbance, (4) biodiversity of soil-dwelling organisms, (5) resistance to weed establishment, and (6) stable populations of beneficial insects. Several studies have...
Effects Of Agroecosystems On Wildlife
Positive Effects of Agriculture on Wildlife Several aspects of agroecosystems can positively affect wildlife populations. One aspect of the fragmentation of an agroecosystems forest mosaic is the creation of edge habitat. This results in the edge effect, or the tendency for the variety and density of some species of plants and animals to increase at the border between different plant communities (Forman, 1997). Edges, or ecotones, contain species from both habitats as well as a subset of...
Intraspecific Diversity of Beneficials
A common feature of many agroecosystems is a reduction in species richness coupled with high populations of selected other species. With parasitic Hymenoptera, for example, the phenomenon may affect not only the interspecific relationships within certain parasitic spectra, but also the intraspecific diversity of individual parasitoids (Unruh and Messing, 1993). There may be changes in the gene flow between populations from different host species as well as certain dominance of features in...
Pathways Toward The Future
In the preceding sections we have outlined many of the problems and potentialities of local in situ management and conservation of plant genetic resources. In proposing positive future steps for effective conservation, we utilize a dichotomy articulated by Janice Alcorn as a discussant at a symposium on Local-global (Dis)articulation of Plant Genetic Resources (Rhoades and Nazarea, 1996). Alcorn noted that in the rush to address critical issues of genetic resources, farmers' rights and...
Omnivory
Omnivores add connectedness to the food web by feeding on more than one food source (Coleman et al., 1983). Omnivorous nematodes, such as some Doryla-midae, make up only a small portion of the total nematodes in agricultural ecosystems (Wasilewska, 1979 Neher and Campbell, 1996). They may feed on algae, bacteria, fungi, and other nematodes. Collembolans are often microbial feeders, but may also be facultative predators of nematodes (Snider et al., 1990). Mites that feed on both microbes and...
Patterns Of Landscape Structure And Insect Biodiversity
An unfortunate trend accompanying the expansion of agricultural monocultures is that it occurs at the expense of surrounding natural vegetation which serves to add biodiversity to the landscape. One consequence of this trend is that the total amount of habitat available for beneficial arthropods and natural enemies of pests is decreasing at dramatic rates. The hypothetical impact of habitat fragmentation on the survival of natural enemies in agroecosystems is depicted in Figure 7. The...
Soil Structure
Microbes play a major role in the formation of soil structure (Lynch and Bragg, 1985 Tisdall, 1991). Fungi and actinomycetes produce hyphal threads that bind soil particles together. Extracellular polysaccharides produced by bacteria and fungi bind soil particles together, assisting in building soil structure. Humic materials from microbial action form organic matter clay complexes. This action reduces erosion, allows for good water infiltration, and maintains adequate aeration of the soil....
Summary
Natural community beneficials in cropping systems are interlinked with surrounding vegetation matrices. Their biodiversity is affected by numerous farmland approaches and activities. But much of the biological aspects of the beneficials, their specific interrelationships, differences in relative abundance, performance, and management in and between agroecosystems, geographical areas, climatic zones, etc. are yet to be determined or determined in detail. The ecological planning, selection,...
Agricultural Disturbances
Disturbance can alter the diversity of an ecosystem (Atlas, 1984) directly by affecting survivorship of individuals or indirectly by changing resource levels (Hobbs and Huenneke, 1992). Sometimes, diversity measurements reflect the result of disturbance caused by pollution and or stress. For example, taxonomic diversity of microinvertebrate communities was less in polluted or disturbed than in unpolluted or undisturbed agricultural sites (Atlas et al., 1991). Pollution eliminates sensitive...
Biodiversity Crisis
Biodiversity or natural habitat resources are dwindling, in large measure because of urban and agricultural spread and commercial development (LaSalle and Gauld, 1992). Natural enemies that demonstrate an ability to become community members in an agroecosystem have, in general, a much better chance to survive compared with those associated only with natural ecosystems. Through adaptation, at least some beneficials have overcome or are overcoming the biodiversity crisis by moving into or between...
Introducing Agroecosystems And Indicators Of Quality
Agroecosystems include highly managed, productivity-oriented systems which vary widely in their dependence on chemical, energy, and management inputs, and are one conservation tactic identified to protect extant diversity (Soule, 1993). Defining quality indicators associated with agroecosystems relies on concepts not inherent in the system itself, just as do efforts to define sustainability. Rather, concepts such as sustainability or quality imply values derived from a human or cultural...
References
J., and Bassham, C. R., 1988. Autogenic succession in a subtropical savanna conversion of grassland to thorn woodland, Ecol. Monogr., 80 272-276. Bojos, J., 1996. The Economics of Wildlife Case Studies from Ghana, Kenya, Namibia and Zimbabwe, AFTES Working Paper No. 19. World Bank, Washington, D.C. Bojos, J. and Casells, D., 1995. Land Degradation and Rehabilitation in Ethiopia A Reassessment, AFTES Working Paper No. 17. World Bank, Washington, D.C. Bruenig, J. 1991....
Urban Succession
AGRICULTURAL SUBURBAN OLDER COMMERCIAL CORPORATE INDUSTRIAL RESIDENTIAL AGRICULTURAL SUBURBAN OLDER COMMERCIAL CORPORATE INDUSTRIAL RESIDENTIAL P R > 1 P R P R < 1 Figure 5 Changes in P R ratios during ecological (autotrophic) and urban (heterotrophic) succession. Although P R decreases as the amount of biological material increases during ecological succession, the result is a mature (climax), sustainable community. In contrast, the accumulation of physical material during urban succession...
Rhizosphere
Plants may be an important selective force for the diversity of rhizosphere populations of bacteria and fungi through their influence on soil nutrients. Rhizo-sphere soil can be defined as that volume of soil adjacent to and influenced by plant roots (Metting, 1993). It is a region of intense microbial activity because of its proximity to plant root exudates, making rhizosphere microbial communities distinct from those of bulk soil (Curl and Truelove, 1986 Whipps and Lynch, 1986). Micro-bial...
Conclusion
The diversity of microorganisms is greater than any other group of organisms on Earth, but our knowledge of the diversity and genetic wealth in these groups is limited. Microorganisms are key to the integrated functioning of nutrient cycles and decomposition, soil structure, and plant growth in agricultural systems. Research is needed to increase our understanding of the diversity and function of microbial communities in agroecosystems. In agroecosystems, microbial diversity will influence all...
Biodiversity Monitoring
Biodiversity is described at three fundamental levels ecosystem diversity, species diversity, and genetic diversity (Office of Technology Assessment, 1987). Changes in the diversity can be monitored by indicator species (Noss, 1990). Monitoring biodiversity in farmlands should account for biota both in the crops and in the soils. Apart from the common crops and livestock in agriculture, some 200,000 other species of plants and animals are involved in agricultural production and perform many...
Contents
Confronting the Diagnostic Challenge Technical vs. Adaptive Problems Introducing Agroecosystems and Indicators of Quality Defining Agroecosystems Factors Affecting Quality Indicators Quality Indicators Linking Biodiversity with New Technologies Conserving, Maintaining, and Using Biodiversity Minimizing Chemical Inputs International Collaboration in Biotechnology Research Findings Anticipating Adaptive Challenges for Developing Countries Seminar Findings Examples from IBS Seminars The Technical...
Habitat
Unlike soil macrofauna (e.g., earthworms, termites, ants, some insect larvae), mesofauna generally do not have the ability to reshape the soil and, therefore, are forced to use existing pore spaces, cavities, or channels for locomotion within soil. Habitable pore space (voids of sufficient size and connectivity to support mesofauna) accounts for a small portion of total pore space (Hassink et al., 1993b). Microfaunal community composition becomes increasingly dominated by smaller animals as...
Microbial Impacts On Agroecosystems
Microbes impact agroecosystems through a large list of functions for which they are responsible (Table 2). Soil humus formation, cycling of nutrients, and building soil tilth and structure (Lynch, 1983 Wood, 1991) are distributed among a large number of different genera and species. Microorganisms are responsible for many transformations in soil related to plant nutrition and health. The majority of soil microbes are beneficial to plant growth, but they need to be managed effectively (Lynch,...
Tree Domestication In Progress
Since 1993, ICRAF has initiated programs to identify priority trees for domestication (Franzel et al., 1996) and started germplasm collection in the humid lowlands of West Africa, the semiarid lowlands of West Africa, the Miombo Woodlands of the southern Africa plateau, and in western Amazonia (Leakey and Simons, 1998b). Through these programs ICRAF is developing the concepts, strategies, and policies associated with capturing genetic diversity of a wide range of indigenous trees for growth in...
Community Assembly
Theoretical and experimental studies of community organization have revealed some intriguing phenomena with implications for the development of stable perennial grain polycultures. Such studies have shown that complexity is often the consequence of specific events that occur during community assembly events that are generally undetectable from an examination of extant community patterns alone (Post and Pimm, 1983 Gilpin, 1987 Robinson and Dickerson, 1987 Drake, 1991 Drake et al., 1993). Complex...
Tillage
In a study of the diversity of prairie and cultivated soils, diversity indexes were greater in disturbed or cultivated systems when compared with grassland (Kennedy and Smith, 1995). The increase in diversity with disturbance indicates a change in the microbial community to one that exhibited a greater range of substrate utilization and stress resistance. Soil microorganisms may affect plant growth and may influence plant competition. In turn, plants may act as a selective force for rhizosphere...
Soil Texture and Compaction
Soil texture may impose physical restrictions on the ability of fauna to graze on microbes therefore, texture may play a role in faunal-induced mineralization of microbial carbon and nitrogen (van Veen and Kuikman, 1990). Carbon and nitrogen mineralization is generally faster in coarse than in fine-textured soils. In clay soils, organic material is protected physically from decomposers by its location in small pores. In sandy soils, organic matter is protected by its association with clay...
Key Beneficials in Agroecosystems
Ideal integrated pest control should reflect ecological approaches that not only target the pest, but also account for the key natural enemies and associated interactions (LaSalle and Gauld, 1992 LaSalle, 1993). The success or lack of success of parasitic and predatory species is commonly linked to not only the target host, but other hosts, bioagents, habitats, and abiotic factors. Understanding the host range, host preferences, seasonal occurrence, interspecies competition and displacement,...
Definitions
Before we go further, we need to define some critical terms. First, one needs to realize that biodiversity entails many different things to different interest groups (West, 1995). To some, it is mainly genetic material. To others, it is taxonomic richness, usually species, of biota within plots or more abstract communities and landscapes. To still others, it is properly functioning ecosystems, including indigenous human cultures living in sustainable ways. All these views are legitimate and...
Biodiversity of Beneficials in Insect Pest Control Systems
Biodiversity as a factor in pest control varies widely between countries and areas of the world. Introduction strategies in classical biological control typically center on the full range of beneficials attacking the target pest throughout the world, with the aim to find, select, and use the most promissive agents from the world complex. The introduction of broad-spectrum pesticides starting with DDT contributed to a strong demand for pest-free crops. Resistance to pesticides and pest...
Taxonomic Diversity
The number of known microbial species is estimated to be over 110,000, but only a fraction of these species is identified and even fewer are being studied or are in culture collections (Hawksworth, 1991b). By one estimate, only 3 to 10 of Earth's microbial species have been identified, leaving a vast portion of that biota unknown and therefore unstudied (Hawksworth, 1991a). According to other estimates, the number of microbial species may be as many as 1 million organisms (American Society for...
Strategies For In Situ Agrobiodiversity Conservation By Indigenous Communities
Over the years, we have spent a great deal of time working with subsistence farmers in Asia, Latin America, and the American South (Nazarea-Sandoval and Rhoades, 1994). We have studied these native curators intensively as anthropologists, worked with farmers as members of interdisciplinary teams at International Rice Research Institute (IRRI) and International Potato Center (CIP), and more recently as anthropologists attempting to document and revive landrace use in the southern U.S. through...
Microbial Feeders
Microbial-feeding mesofauna feed on fungi (including mycorrhizae), algae, slime molds, and bacteria by removing them from clumps of decaying material or soil aggregates (Moore and de Ruiter, 1991). Generally, bacterial-feeding nematodes such as Cephalobidae and Rhabditidae (Neher and Campbell, 1996) are abundant in agricultural ecosystems (Wasilewska, 1979 Popovici, 1984). Consumption of microbes by soil mesofauna alters nutrient availability by stimulating new microbial growth and activity...
Cropping Systems
Microbial communities in agroecosystems change with management history. In continuous cropping systems, cycling of pathogens and antagonists of pathogens and changes in crop yields can often be seen due to alteration in the disease pressure over time. An example of this is the decline of a disease of wheat called take-all decline that is the result of a change in the soil microbial community. The microbial community shifts to favor growth of antagonists of the pathogen Gaeumannomyces graminis...
Soil Microorganisms In Agroecosystems
The soil is full of microorganisms such as bacteria, actinomycetes, fungi, algae, viruses, and protozoa. Microbes are classified in categories based on their utilization of carbon and energy and their nutrient requirements (i.e., phototrophs, chemotrophs, autotrophs, heterotrophs, or lithotrophs). This provides limited information, since many situations overlap and refinement is needed (Alexander, 1977 Walker, 1992 Zak et al., 1994). Bacteria and fungi, as primary decomposers in the cycling of...
Value Of Diversity
Diversity in form and function of biotic communities results in the formation of spatial and temporal heterogeneity of organisms that contributes to the overall function of the ecosystem. Individual taxa may have multiple functions, and several taxa may appear to have similar functions. However, function may not necessarily be redundant, because taxa performing the same function are often isolated spatially, temporally, or by microhabitat preference (Beare et al., 1995). Biodiversity allows...
Sources Of Genetic Diversity In Crops
Genetic variation within a crop gene pool can be found within and among professionally bred varieties, landraces or farmers' varieties, and nondomesticated relatives. In addition, new genetic variation can be introduced through mutations and the transfer of genes from different gene pools. Commercially released varieties aim to combine genes for high productivity with those required to meet different needs and environments. They contain a wealth of useful genes and gene combinations and...
The Prairie Model
Natural grassland ecosystems may represent our best benchmarks for sustainability. Prairies (1) protect the soil from erosion, (2) provide their own nitrogen fertility requirements through the activities of both free-living and symbiotic nitrogen-fixing organisms, (3) avoid devastation by weedy invaders, insect pests, and plant diseases, and (4) run on sunlight and available precipitation (Table 1). The vegetation structure of prairies has two important general characteristics that contribute...
International Collaboration In Biotechnology Research
With the two indicators of agroecosystem quality determined, attention is now placed on examples of new technologies. Examples have been selected that take into account the emerging needs of developing countries regarding biotechnology and their ability to collaborate with international research programs. These examples are taken from information collected from IBS policy seminars and its Registry of Expertise. IBS began to collect, analyze, and discuss with client countries its information on...
Agroecosystem Impacts On Microorganisms
Microbial diversity considerations need to be included in soil quality investigations of agricultural lands (Kennedy and Papendick, 1995). Soil quality is critical to the functioning of any ecosystem (Papendick and Parr, 1992). The quality of a soil can greatly impact land use, sustainability, and productivity. Soil quality, the inherent characteristic of a soil, comprises physical, chemical, and biological properties. These properties may be altered through intensive management practices....
Plant Feeders
Plant-feeding nematodes can become abundant in agricultural ecosystems (Wasilewska, 1979 Popovici, 1984 Neher and Campbell, 1996). These nematodes may affect primary productivity of plants by altering uptake of water and nutrients. These abnormalities may result from changes in root morphology and or physiology. For many agricultural crops, a negative relationship between crop yield and populations of plant-feeding nematodes, such as Meloidogyne, Heterodera, and Praty-lenchus spp., has been...
Linkages Between Biodiversity And Sustainability
Management of agrolandscapes for sustainability both influence and is influenced by biodiversity (Paoletti, 1995). Landscape planning is a process through which the conservation and management of biodiversity can be pursued (Rook-wood, 1995). Turner et al. (1995) stressed that there exists a three-way interaction of biodiversity, ecosystem processes, and landscape dynamics at greater scales. Sustainable agricultural practices leading to increased crop and genetic diversity have resulted in...
Approaches To Conservation
Conservation can be broadly considered in two ways ex situ and in situ. Ex situ conservation involves removing reproductive plant material from its natural setting for maintenance in seed or tissue banks or plantations. Because of the finite nature of any living plant material, ex situ conservation also requires regeneration of the reproductive material at given storage conditions and at species-dependent intervals. In situ conservation is accomplished by protecting plant material in the site...
Habitat Management Crop Structure and Diversity
Habitat management is viewed as a strategy aimed at designing and constructing phytocenotic architecture dominated by plants that support populations of natural enemies (Altieri and Whitcomb, 1979 Altieri, 1983). Diversification of habitat is achieved through crop structure, protective refugia, occurrence of alternative prey host, and supplementary food resources (nectar, pollen). Crop structure is the agroecosystem and its specific characteristics, its biotic composition, seasonality, etc....
Biology And Ecology Of Soil Fauna
Soil mesofauna are often categorized by specific feeding behaviors, often depicted as microbial feeders. However, it should be emphasized that many organisms are at least capable of feeding at other trophic groups. As a result, omnivory in soil communities may be more prevalent than assumed previously (Walter et al., 1986 Walter, 1987 Walter et al., 1988 Walter and Ikonen, 1989 Mueller et al., 1990). Our discussion will focus specifically on nematodes, Collembola (springtails), and mites...
The Global Strategy
To assist countries to respond to these imperatives for upgrading the management of animal genetic resources, a framework for a global strategy has been supported and is known as the Strategy for the Management of Farm Animal Genetic Resources. The framework of the Strategy consists of four fundamental components. The Strategy is designed to be comprehensive to emphasize the balanced approach required to understand, utilize, and maintain AnGR better and more cost-effectively over time. The four...
Patterns Of Insect Biodiversity In Agroecosystems
Arthropod diversity has been correlated with aspects of plant diversity in agro-ecosystems. A greater variety of plants conforming to a particular crop pattern should lead to a greater variety of herbivorous insect species, and this in turn should determine a greater diversity of predators and parasites (Figure 5). A greater total biodiversity can then play a key role in optimizing agroecosystem processes and function (Altieri, 1984). Several hypotheses can be offered to support the idea that...
Protozoan Diversity In Agroecosystems
Studies on grasslands (McNaughton, 1977 Tilman, 1996) show that biodiversity stabilizes community and ecosystem processes, although individual species within the system may fluctuate considerably. Tilman (1996) found wide variations in the biomass of the 24 most abundant species of plants in an 11-year study. In a 6-month study of soil ciliates under a spruce stand, Lehle (1992) found that the proportions of the three dominant ciliate species fluctuated widely Cyclidium muscicola ranged from 8...
Research Agenda And Findings That Support The Model
Question 1 Can a Perennial Grain Yield As Well As an Annual Grain Work at the Land Institute to domesticate perennial grains began in 1978 with an inventory of nearly 300 herbaceous perennial species for their suitability to the environment of central Kansas and their promise as seed crops. A second inventory examined the agronomic potential in 4300 accessions of perennial grass species within the C3 genera Bromus, Festuca, Lolium, Agropyron, and Elymus (Leymus). From these inventories, a...
Role Of Soil Protozoa
Microarthropods and larger fauna, especially earthworms, increase the rate and amount of mineralization by comminution of organic matter and by redistribution of hot spots of activity through movements. However, mineralization and return of nutrients to plants occur in the water films covering soil aggregates and filling their pores. Here, bacteria and fungi decompose organic matter and immobilize the extracted nutrients into their bodies, but grazing by the microfauna, protozoa, and nematodes...
Plant Biodiversity And Insect Stability In Agroecosystems
From the early 1970s on, the literature provides hundreds of examples of experiments documenting that diversification of cropping systems often leads to reduced herbivore populations (Andow, 1991 Altieri, 1994). Most experiments that have mixed other plant species with the primary host of a specialized herbivore show that, in comparison with diverse crop communities, simple crop communities have greater population densities of specialist herbivores (Root, 1973 Cromartie, 1981 Risch et al.,...
Ecosystem Processes
Micro- and mesofauna contribute directly to ecosystem processes such as decomposition and nutrient cycling in complex and interactive ways (Swift et al., 1979). Bacteria, actinomycetes, fungi, algae, and protozoa are primary decomposers of organic matter. These microorganisms are involved directly with production of humus, cycling of nutrients and energy, elemental fixation, metabolic activity in soil, and the production of complex chemical compounds that cause soil aggregation....
Augmentation Of Beneficials
Augmentation, broadly defined, covers all of the activities that improve the effectiveness of beneficials (DeBach, 1964), such as new species releases (inoculative or inundative), planned genetic change, landscape modification, and so on. The addition of a new species or strain of species into a new area increases species diversity, but it can also affect interspecific relationships and population genetic characteristics. Releases of Mass-Reared Natural Enemies There are two main types of...
Evolution Of The Global Strategy
The Food and Agricultural Organization (FAO) mandate, which is regularly reviewed by its 174 member governments, covers (1) collating, analyzing, and reporting information (2) providing technical assistance, with emphasis on the developing world and (3) providing a forum for intergovernmental discussion and policy development. The member governments have resolved that FAO should lead, coordinate, facilitate and report on the Strategy for the Management of Farm Animal Genetic Resources...
Linkages Between Agricultural And Urban Components Of The Landscape
Figure 3 The development of an agro-urban sustainable (P R 1) landscape. The town marketplace historically was closely linked to the agricultural landscape. Sustain-ability in the modern agro-urban landscape increasingly must be based on the management of suburban areas (ecotones) as natural linkages between urban and agricultural systems. Figure 3 The development of an agro-urban sustainable (P R 1) landscape. The town marketplace historically was closely linked to the agricultural landscape....
Role Of Arthropods In Ecosystem And Agriculture
Today, scientists worldwide are increasingly starting to recognize the role and significance of biodiversity in the functioning of agricultural systems (Swift et al., 1996). Research suggests that, whereas in natural ecosystems the internal regulation of function is substantially a product of plant biodiversity through flows of energy and nutrients and through biological synergisms, this form of control is progressively lost under agricultural intensification and simplification, so that...
