Explain human components in agricultural ecosystem
Answers
Answer:
Biotic components include plants, animals, decomposers. Nonliving components include air, water, land.
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The biotic component of an ecosystem has been classified into three groups:
Producers (green plants)
Macro consumers (usually animals)
Micro consumers or decomposers (organisms like bacteria and fungi)
Answer:
Agroecosystems comprise 30% of the Earth’s surface (Altieri, 1991), and according to Swift et al. (1996) can be defined as, “the ecosystems in which humans have exerted a deliberate selectivity on the composition of the biota i.e., the crops and the livestock maintained by the farmer, replacing to a greater or lesser degree the natural flora and fauna of the site.” Agroecosystems provide various ecosystem services, and management practices used in the agroecosystems determine the state of the global environment (Tilman et al., 2002). However, most agroecosystems are disturbed more frequently and with greater intensity than natural ecosystems resulting in reduced biological diversity (Gliessman, 2015). Poor land management practices within many agroecosystems result in reduced soil organic carbon (SOC) and crop production, and increased erosion. About 50% of the global arable land is already under mechanical and chemical intensive agriculture (Cohen, 1995), which requires high inputs of nutrient, energy, and water (Krishna, 2010). In this chapter, alternatives to mechanical and chemical intensification of agriculture using an approach called sustainable intensification of agroecosystems based on the concept of ecological intensification described by Gaba et al. (2014) will be addressed. Sustainable intensification often reduces mechanical and chemical inputs and increases biological diversification of agroecosystems. Examples include the use of diverse crop rotations, cover crops, no-tillage (NT), and the integration of livestock onto cropped lands. The adoption of diversification in agroecosystems has several advantages including building SOC, reducing insects/pests and diseases, and over time may result in improved crop productivity and other ecological services. However, as stated by Gaba et al. (2014) “manipulating biotic interactions is not necessarily gentler than conventional agriculture and may also have undesirable effects.” Sustainable intensification based on diversification of agroecosystems also includes a number of concerns such as higher initial cost, increased management skills, and an increase in uncertainty during the transition from mechanical and chemical intensification to sustainable intensification (Fig. 9.1). Gliessman (2015) defined diversification in agroecosystems as “Diversity is at once a product, a measure, and foundation of system’s complexity—and therefore, of its ability to support sustainable functioning. From this perspective, ecosystem diversity comes about as a result of ways that different living and nonliving components of the system are organized and interact. From another perspective, diversity as manifested by the complex of biogeochemical cycle and the variety of living organisms—is what makes the organization and interaction of the system possible.” Diversification can generate greater employment opportunities and higher incomes for producers (Ghosh et al., 2014). A few examples of diversified farming systems include complex crop rotations, cover crops, and integrated crop-livestock (ICL) systems. This chapter focuses on the impacts of diversified agroecosystems on soil carbon (C) dynamics.