Acta Geographica Sinica ›› 1998, Vol. 65 ›› Issue (s1): 11-20.doi: 10.11821/xb1998s1002

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ECOLOGICALLY STRATEGIC POINTS IN LANDSCAPE AND SURFACE MODEL

Yu Kongjian   

  1. Department of Urban and Environmmental Sciences, Peking University, Beijing 100871
  • Received:1997-05-16 Revised:1998-02-04 Online:1998-12-15 Published:1998-12-15
  • Supported by:

    Suppurcud by National Natural Science Foundation of china,No.5978010

Abstract: Various processes occur across a landscape, including ecological processes such as the movement of species, the flow of nutrients, the spread of fire and other disturbances, and the diffusion of pollutants; economic processes such as land conversion for agricultural production, marketing of new product, transportation and immigration; political and diplomatic processes such as the construction of political influence sphere at local, national and global scale. At the fact of limited space and resources on the surface of the earth, a generic issue regarding these processes across the landscapes is : how to control (promote or retard) the processes efficiently, namely using less energy and space for a bigger influence sphere.The overall assumption for this issue is that, there are some positions and portion in a land-scape that may have critical influence on a certain process across the landscape. These critical positions in a landscape are called strategic points. Occupancy of these strategic points may give a process the momentum of controlling and covering the landscape more effectively, due to their quality of:Initiative, occupancy of these points may give the process the advantage of leading the game;Co-ordination, occupancy of these points may give the process the advantage of forming an overall influence sphere;Efficiency, occupancy of these points may give the process the advantage of having a bigger coverage of the landscape while costing less energy.By identifying and using these critical positions and portions in the landscape, therefore, may unproportionately increase the efficiency of controlling this process.It is further assumed that, in order to take control of the landscape, the process has to overcome a certain resistance. A resistance surface can therefore visualize the dynamics of the process itself. The resistance surface resembles a topographic surface, indicating where the pro-cess (flow) diverges or converges. It is. therefore, possible to identify strategically important positions or portions in a landscape that may have important influence on the dynamics of the process.Assuming species movement across a landscape is a competitive gaming process of control and coverage against some resistance, this paper discusses a methodology of identifying strategic points according to the properties of resistance surfaces which resembles a gaming board as well as a topographic surface. Three types of resistance surfaces are discussed:The archipelago type: where lower resistance islands are surrounded by higher resistance matrix, representing such landscapes as agricultural fields dotted with native forest patches.The network type; where the lower resistance portions form a linear network surrounded by higher resistance matrix.The plateau type: where, areas with higher resistance are surrounded by lower resistance matrix.Accordingly, five types of strategic points are identified in terms of their locations. They are strategic points at saddle points , at intersections, at the center, at an edge and at a corner. Strategic points for biodiversity conservation are minimax points in a given resistance surface as-sociated with the dispersibility of a certain species. A case study is used to illustrate the method-ology. The rules leading to the strategic points are largely hypothetical, though supported by a limited number of observations. This approach may provide a framework and a new model of thinking for field observations of landscape ecology as well as landscape change.

Key words: strategic points, landscape ecology, landscape pattern, spatial analysis

CLC Number: 

  • P901