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40 2019 ND-CP 413905
- Điều hướng trang này:
- ENVIRONMENTAL CONCERNS Agro-ecosystems analysis and landscape value
| CONCEPTS AND DEFINITIONS
The definitions and concepts outlined in this section should be seen as complementary to the basic concepts described in the 1976 Framework (see Glossary). The UN definition of land and land resources (UN 1995) is briefly discussed in Chapter 1. The list of definitions and concepts is not exhaustive. The concepts discussed are related to the environment or to sustainable livelihood. Issues of scale are discussed separately as they extend across themes of production, environmental concerns and social considerations. In a final section, the concepts discussed are linked to the basic concepts of the 1976 Framework. ENVIRONMENTAL CONCERNS Agro-ecosystems analysis and landscape value The World Resources Institute recognizes five major categories of ecosystems, accounting for almost 90 percent of the earth’s land surface: agro-ecosystems, and coastal, forest, freshwater, and grassland ecosystems. It defines an agro-ecosystem as a biological and natural resource system managed by humans for the primary purpose of producing food as well as other socially valuable non-food goods and environmental services (Wood et al., 2000). According to FAO (1998), agro-ecosystems are those ecosystems that are used for agriculture, and comprise polycultures, monocultures, aquaculture, rangelands, pastures and fallow lands as well as mixed systems including crop-livestock systems, agroforestry and agro-silvo-pastoral systems. Drawing on systems and ecological thinking, Conway (1985, 1986, 1987) developed agro-ecosystem analysis. This combines analysis of systems and system properties (productivity, stability, sustainability and equitability) with pattern analysis of space (maps and transects), time (seasonal calendars and long-term trends), flows and relationships (flow, causal, Venn and other diagrams), relative values (bar diagrams of income sources etc.), and decisions (decision trees and other decision diagrams). Agro-ecosystem analysis was so powerful and practical that it quickly overlapped with and contributed to rapid and participatory rural appraisal. A full analysis goes beyond the process of land evaluation and therefore is not considered in the development of a revised framework. The emphasis is on the combination of productivity and environmental concerns into a revised framework that aims at sustainable use of land resources. The agro-ecosystem is a key factor in shaping the landscape. Agricultural landscapes are valued by society beyond the farming community. Focusing on all social, economic and environmental issues that are relevant to the agro-ecosystem, the concept of landscape provides an overarching system in which the environmental media air, soil, water and nature (biodiversity) are integrated. Although the concept does not exist in all societies, landscapes are the product of the interaction between human societies, cultures and the natural environment (Décamps 2000). The concept of landscape enables the introduction of indicators for measuring the impact of agricultural policies on the land. Factors such as increased mechanization, changes in farm and field sizes, increased specialization and simplification of crop rotations lead to a reduction Chapter 3 – Expansion of concepts and definitions 19 in landscape diversity (Meeus 1993). Traditional landscape features are often lost through farm abandonment or changes in the agro-ecosystem. Total abandonment of agricultural land results in the emigration of rural people and the deterioration of traditional farm buildings, which themselves form landscape features. In a number of countries, much land abandoned by agriculture is planted with tree species for pulp production, creating a uniform landscape, poor in biodiversity and landscape features. tải về 0.57 Mb. Chia sẻ với bạn bè của bạn:
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