Components Of Agroecosystems Research Articles

An input/output methodology to evaluate farms as sustainable agroecosystems: an application of indicators to farms in central Italy

Agricultural researchers recognize the importance of the sustainability of agricultural systems and the need to develop appropriate ways to measure sustainability. The search for agroecosystem performance indicators (APIs) is an urgent task to develop understanding and to facilitate decision-making processes. The paper provides an input/output methodology for a farming system analysis in terms of both energy and monetary values, measurements that are sufficiently homogenizing and comprehensive to document patterns of agroecosystem transfers of bio-physical entities and socio-cultural values. This methodology was applied to two adjacent farms located in Central Italy, which differed in the farming system adopted (mixed farming and arable farming) and in the level of external input applied. A broad range of APIs (structural and functional, direct and crossed) was developed to analyze both the fundamental energy transfers (and associated allocation of monetary values) between the crucial agroecosystem components and the overall efficiency of the farming system in transforming different external input into output. This analysis shows that energy and monetary values do not offer a single, coherent account of the functioning of farm systems. The study stresses the need for the development of an environmental accounting method, which integrates ecological and economic aspects. For the present, it is recognized that structural and functional APIs calculated according to energy, rather than monetary, values are more meaningful in both the designing of sustainable farming systems and in decision-making processes.

Weed ecology and ethics

Weed Scientists, like many other agricultural scientists and natural resource land managers, often engage in debate with other members of society about values and perceptions of food and fiber production. The focus of the debate is usually on the tools and tactics to grow crops, produce wood, or manage grazing land. Environmental ethical issues have dominated discussions among the membership of WSSA for decades. Examples include the decade-long debate over 2,4,5-T use in forestry and now water quality and human health concerns about atrazine use in agriculture. Ecology is a scientific discipline that seeks knowledge about the interactions of organism, their environments, and, more broadly, the effect of human activities on them. Because weeds are a consequence of how we grow food, the study of both ecological and human components of agroecosystems should allow weed scientists to construct management strategies that more fully address the production, environmental, and social implications of weeds and weeding.

Fish Community Structure as a Measure of Degradation and Rehabilitation of Riparian Systems in an Agricultural Drainage Basin

/ Assessing the health of ecological components of agroecosystems may be accomplished by examining changes in the drainage basin, which serves as an integrator of the agroecosystem landscape. In this study we examined fish communities in terms of an array of indicators of structure and related these to changes in riparian vegetation and agricultural practice. Evidence suggests management practices designed to foster healthier environments by, for example, reestablishing riparian vegetation were associated with positive impacts on the integrity of the fish community. At the same time, continued intensification of agricultural practices in parts of the drainage basin in recent years likely has had an off-setting influence in overall improvements in agroecosystem health. Assessments of changes in the structure of the fish associations provide the balance sheet by which the counteracting influences can be aggregated and assessed.KEY WORDS: Fish community structure; Riparian system; Agricultural drainage basin

Making Tradeoffs for Agroecosystem Health

ABSTRACTExisting definitions of agroecosystem health do not address one of the most important issues, namely, how tradeoffs should be made among different components of an agroecosystem. To resolve this issue, it is important to be clear on which perspective is being taken in any health assessment. An internal perspective would focus on the health of the biophysical components of the agroecosystem, whereas an external perspective would focus on human communities. This article proposes a three‐stage, transdisciplinary approach to agroecosystem health, called a Framework for Agroecosystem Health Tradeoffs, which uses internal and external perspectives at different stages. In the first stage, the type of ecosystem and the time and spatial scale of concern are identified. Once this is established, required levels of biophysical indicators are set and monitored to ensure that basic internal needs for agroecosystem survival are met. In determining levels of biophysical indicators, “positivistic” scientific analysis would be required as well as normative judgments by society on acceptable levels of risk. The third stage involves determining the potential for making tradeoffs in the agroecosystem that would be beneficial to society without affecting the required levels of biophysical indicators specified in the second stage. Economic analysis and community consultation would be used to determine which agroecosystem components or services are valued most by society so that decisions on tradeoffs could be made. Although there remain practical problems in implementing this approach, the notion of setting minimum constraints which human activity cannot violate and making the best tradeoffs possible after these constraints are met provides a useful framework to begin putting agroecosystem health into practice.

A Framework for Regional Agroecosystems Characterization Using the National Resources Inventory

An agroecological framework is used to examine the relations among natural resources and agriculture. Spatial representation of selected agroecosystems characteristics was accomplished using the National Resources Inventory (NRI). Natural resource and anthropogenic variables from the NRI were spatially aggregated to produce maps showing the regional variability in area-weighted values of agroecosystem components. Maps of natural vegetation, agricultural land use, crop diversity, artificial drainage, irrigation, net soil loss, and conservation practices show the extent to which resources have been modified to support agriculture in the Midwest. The frequency of land used for crops and pasture exceeds 70% in much of the region. Natural vegetation occupies less than 10% of the land in many areas. Subsurface and surface drainage, more than 35% of some areas, has contributed to loss of wetlands having a direct effect on water quality. Irrigation has diverted water from natural ecosystems and increased the potential for leaching of agrichemicals. Excess erosion may threaten long-term productivity in parts of the region even though conservation practices have been implemented. Examination of these and other elements in an agroecosystem framework may be useful in the search for systems to sustain agriculture and natural resources in the region. Such a framework can also be used to locate areas where mitigation of degraded resources is most needed; identify areas where research into causes of degradation can yield the most information; and where policies to improve off-site damage may be most effectively implemented.

Integrated Farming: an Ecological Farming Approach in European Agriculture

European agriculture operates in challenging times as it faces uncertainties arising from economic, political, environmental and other pressures. In the arable sector, there are serious problems associated with overproduction and declining farm incomes as well as concerns about species decline and the pollution of ground and surface waters by agrochemicals. Such issues are forcing a fundamental re-orientation in agriculture. An Integrated Farming System (IFS) is identified as a most promising approach. It integrates natural regulatory components into farming activities with the aim of replacing purchased off-farm inputs, whilst maintaining farm income. Farm-scale trials across Europe indicate positive benefits of IFS. Yield potential does not deteriorate, agrochemical inputs are reduced and several agroecosystem components are enhanced without losses in financial returns. This paper discusses developments in IFS, together with possible technology transfer systems, in the context of the new, environmentally-orientated CEC-agropolicy to achieve sustainable agriculture in Europe.

Nitrogen Cycling in Conventional and No-Tillage Agro-Ecosystems: Analysis of Pathways and Processes

(1) The nitrogen dynamics of conventional and no-tillage agro-ecosystems are compared. Sorghum/rye (1978-1979) cropping systems were followed in rotation by soybean/rye (1980-1981) systems. Measurements of ecological processes including crop and weed production, litter decomposition, insect consumption, along with solution chemistry of soil, precipitation, throughfall, and ground water provided the data base for modelling nitrogen cycling in the two tillage systems for four complete annual farming cycles (two sorghum/rye and two soybean/rye). (2) Summary budgets indicated that both similar and dissimilar nitrogen cycling processes were occurring in conventional and no-tillage agro-ecosystems. Differences between agro-ecosystems were not definitive but suggestive of a trend of increasing ecosystem divergence through time. (3) Nitrogen fluxes between several agro-ecosystem component pairs were increased by ploughing. Crop shoot to root ratios differed between tillage treatments, suggesting distinct nitrogen uptake and storage strategies. (4) As a consequence of leaving crop and weed residues on the soil surface, no-tillage soil maintained higher (t30, P < 0.05) organic nitrogen in the upper soil layer (0-10 cm) than conventionally tilled soil. (5) Grain yields for the 4-year period were insensitive to tillage practices except during a drought year (1981) when no-tillage systems yielded higher (t30, P < 0.01) than conventional tillage. (6) Arthropod species diversity and weed biomass were higher (t30, P < 0.05) on several occasions in no-tillage systems. (7) We conclude that soil tillage practices were important regulators of nitrogen flux between agro-ecosystem components and nitrogen storage capacity within them. The undisturbed soil and litter layers of no-tillage systems generate complex decomposition subsystems which mimic those found in natural terrestrial ecosystems. We speculate that biologically-mediated nitrogen-retention mechanisms develop and operate to a greater extent in no-tillage than in conventional tillage systems.

The Ecological Role of Weeds in Insect Pest Management Systems: A Review Illustrated by Bean (Phaseolus vulgaris) Cropping Systems

Abstract Weeds are major components of agro-ecosystems and they affect the biology of pests and beneficial insects in several ways; provision of flowers, presence of neutral insects, modification of crop microclimate, production of chemical stimulus, alteration of colonisation background, etc. The more relevant beneficial crop–weed–insect interactions are discussed. The role of weeds in regulating pest populations is illustrated by studies on bean (Phaseolus vulgaris L.) cropping systems, in which chemical interactions between Empoasca kraemeri Ross & Moore and two grass weeds were identified. It is proposed to continue and develop this kind of research in order to incorporate weeds into pest control strategies.