Assessment of Biodiversity Value by the Possibility of Connectivity (PC)-Based Method

The assessment of biodiversity was of great importance in the evaluation system of ecosystem services. Currently, compared with the method adopted actual habitat size which was the popular method in most of the studies, the method used landscape connectivity had more advantages in reflecting the spatial distribution of the value of biodiversity. Moreover, the method with landscape connectivity was more conductive to identify the key area of biodiversity conservation, which had significance in guiding the urban planning. In our paper, a method of landscape pattern was proposed for the assessment of biodiversity value that considered both habitat size and spatial connectivity, which regarded the index of possibility of connectivity (PC index) as its primary parameter. We took Miyun County as case study to calculate the biodiversity value by both the popular method and the proposed method. The calculation of biodiversity value covered six land use types: grazing land, forest land, cropland, water area, built-up land, and unused land. Furthermore, we had identified the key patches for biodiversity conservation by the reclassification of the biodiversity value. The biodiversity value had been reclassified into internal value and external value for the identification of key conservation patches. As a result, we concluded the total biodiversity value of each land use type we had concerned: grazing land was 3.69×10⁶ Yuan ha^-1 year^-1, forest land was 132.39×10⁶ Yuan ha^-1 year^-1, cropland was 5.65×10⁶ Yuan ha^-1 year^-1, water area was 18.94×10⁶ Yuan ha^-1 year^-1, built-up land was 0, and unused land was 0.11×10⁶ Yuan ha^-1 year^-1. Then, for the identification of key patches, we found that there were three kinds of key patches:(1) the patches with larger habitat size;(2) the satellite patches around the large patches as the undertaken area for biological migration;(3) the stepping stone patches.