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when a species travels across landscape type i. While f is some unknown function, the sum of the weighted distance (Di* Ri) , or the 'cumulative resistance' can be taken as an indication of relative accessibility of the cell to the species through one possible route. There are numerous routes from the sources to the cell, and the routes with the lowest cumulative resistance, namely minimal cumulative resistance (MCR) can be used as the relative measurement of the accessibility of this cell from the sources (habitats of target species). Resistance classification (Ri ) is based on individual cells of 25 by 25 meters in size. An interactive interface of the GIS model using ARC/INFO is developed to allow the processing of more precise data. Land use and land cover are the major factors contributing to the resistance of the landscape. In our case, it is reasonable to assume the more similar a cell to the natural habitats the less the resistance to the target species of our concern. Eight major land use and land cover categories are observed and they are closely associated with the degree of naturalness or the intensity of human disturbances; these categories range from developed areas to agricultural fields, grass lands, shrubs, coniferous forests, mixed forests, the remnant subtropical forests and water. From developed area to the remnant sub-tropical forests, the degree of human disturbance increases, in this case it is assumed that the resistance to the dispersal of native target species increases accordingly. The developed areas (including roads, housing, tourist service center) have the highest resistance to all target species (assigned a value 10) and the natural remnant forests the lowest resistance to the target species (assigned value 0) . Water bodies are assigned a high resistance value to the medium-sized mammals but have a moderate resistance to pheasants and low resistance to amphibians (here the quality of water is considered). The topographical factors including elevation and slope also contribute to the resistance to some species. For the medium-sized mammals in this case, gentle slope is considered to have less resistance than a steep slope, the extremely steep slope becoming a barrier to movement. For the pheasants, these topographical factors are not important. Amphibians are sensitive to the hydrological situation, which, in this case is associated with the elevation because of the unique geological formation of this area. Based on the resistance map, an accessibility surface can be developed using the function discussed above. The resultant accessibility surface resembles a topographic surface that is made up of equal-valued MCR contours. Following Warntz's model of surface interpretation (Warntz, 1966), it 'dips' at the sources, has 'peaks' that are least accessible to target species, has 'courses' with lower MCR value and run from 'pits ' to 'pits', and has 'ridges' with higher MCR values and run from 'peak' to 'peak'. On each of the 'courses' or 'ridges' there is one 'pale' or 'pass'. From the MCR surface, one can also recognize the potential cliffs where values increase or decrease dramatically, and the potential flat planes where the species can spread quickly over the landscape. The accessibility surface, therefore, reveals the potential patterns of coverage by the target species and the strategic values of landscape in terms of species dispersal and maintenance (Yu, 1995a-b). Based on the features of the acc