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essibility surfaces, four structural components can be identified: buffer zones, inter-source linkages, radiating routes and strategic points. These four components, specified by certain quantitative and qualitative parameters, together with the identified sources (native habitats) compose a security pattern (Figure 3). Changes in these components, quantitatively or qualitatively, will dramatically affect the security of the targeted processes. Figure 3 A schematic picture showing a typical eco logical SP Among others, three series of ecological SPs are identified respectively at high, moderate and low security levels for different groups of species, e.g. Figure 4-6 for the medium-sized mammals in this case. They could be combined into corresponding overall ecological SPs. These ecological SPs can be used by ecologists as defensive frontiers for the defense of the ecological processes at various security levels in the process of landscape planning and change. Figure 4 An accessibility surface for the medium-sized mammals and an ecological SP at a less secure level. The SP is composed of sources, strategic points and shortest inter-source linkages Figure 5 An ecological SP for the medium-sized mammals at a highly secure level. The SP is composed of sources, strategic points, all possible inter-source linkages, big buffer zones and some radiating routes Figure 6 An ecological SP for the medium-sized mammals at a moderately secure level and the impact of tourist development. The SP is composed of sources, strategic points, some inter-source linkages and some buffer zones. Visual SPs: Tourists' Defensive Frontiers The visual SPs are defined on the basis of critical landscape interpreted by visual sensitivity surfaces which are a combination of landscape visibility and preference evaluation. The calculation and mapping of landscape visibility were carried out using function that most GIS packages contain. GIS mapping of landscape preference is relatively more complicated. Firstly, 572 individual from China and USA were interviewed as to their preference evaluation for various landscapes in the case study area (for detailed discussion see Yu, 1995c). Secondly, factor analysis and regression analysis were used to build the preference models. These preference models show the contributions of various spatial information to the visual quality of the landscape. This spatial information consists of landscape elements including water, rocks, vegetation, tourist service buildings, fields, weather conditions, and spatial dimensions associated with the position of viewers including foreground, mid ground and background. Both types of spatial information are classified, mapped and analyzed using GIS. Finally, GIS was used to develop the landscape preference map based on the landscape preference model and the spatial information. The visual security patterns (SPs) are defined in association with various security levels. Using the histograms of visibility and preference distribution patterns, some thresholds can be identified and used for the identification of visual security levels (Yu, 1995b). Three levels of SPs are identified: low, medium and high. These visual SPs could be used as defensive frontiers by the defenders of visual perceptual processes and tourism during the procedure of spatial bartering and bargaining. Agricultural SPs: Farmers' Defensive Frontiers Local farmers have depended on their land for hundreds of years. Population gr