英语论文网

owth requires more land to be converted into agricultural fields. In a certain sense, agricultural conversion in this case study is an issue of survival of the local people in this area. The potential security levels farmers want to achieve are normally determined by socio-economic analysis on local, regional and even national scales. This case study addresses the issue of agricultural SPs based on investigation of the landscape at the local scale and focuses on the issue as to where land conversion should pause or accelerate in terms of efficiency of productivity and impact on other processes in the landscapes. The procedure of identifying agricultural SPs and ecological SPs is similar. Agricultural conversion is considered a process of disturbance with the seventy villages in the study area taken as the source of the spread of the disturbance. The intermediate landscapes are evaluated according to their resistance or cost of agricultural conversion. A convertibility surface (or the potential of conversion) is developed based on the cumulative resistance of intermediate landscapes. Based on this convertibility surface, agricultural SPs are identified at some thresholds or strategic values. Various agricultural SPs were identified corresponding to different security levels: low, medium and high. They could be used as defensive frontiers by defenders of the process of agricultural conversion in the spatial bargaining and bartering of landscape change and decision making. Alternative Changes Based On SPs Various alternative change models can be developed based on SPs. To illustrate this case four change alternatives are discussed as examples: Differentiation Of Management Concentrations Based On SPs At the highest level of the management hierarchy is the differentiation between landscape conservation, development (mainly agricultural conversion) and an integration of both (Figure 7). The gener al management differentiation can be further sub-categorized, when the environmental concern is specified into ecological and visual aspects. A weighing system has to be used when combining SPs of various ecological processes into an overall ecological SP. In this case, it is assumed all of the individual component SPs have the same weight (= 1). Figure 7 Management differentiation based on two general SPs of environmental conservation and agricultural conversion Strengthening Landscape Infrastructures Based On SPs Taking ecological processes as examples, landscape ecological infrastructures can be strengthened by consolidating the SP components . These consolidations include, but are not limited to, the following aspects of improvement in quantity and quality: (1) Increasing the buffer zones and making the intermediate landscapes more hospitable to native species, (2) having alternative linkages, widening the linkages and improving the connectivity of the linkages, (3) widening the radiating routes with native plants, (4) introducing native patches at the strategic points and expanding their dimensions. By these quantitative and qualitative improvements of the components of the ecological SPs, the security of the landscape for the ecological processes can be improved proportionately. This gradual procedure, however, after reaching a certain threshold, will dramatically increase the security of the landscape and another security level for ecological processes will be achieved, e.g. from Figure 4 to Figure 5. Modifying Introduced Change M