| Summary: | 碩士 === 義守大學 === 土木與生態工程學系 === 103 === Because of various land uses by human, undisturbed habitat patches are reduced and splited in landscape and resulting in the habitat fragmentation. Landscape connectivity was reduced greatly by dissecting previously large patches into smaller ones. Hindering movements of species cause biodiversity loss and population extinction crisis. Landscape ecologists applying percolation theory and neutral models try to establish a reference baseline, to explore the relationship between landscape connectivity and amounts of habitat, and to understand the percolation threshold phenomenon of habitat fragmentation.
Current researches on the computations of landscape percolation threshold mostly are based on infinite area and square aspect ratio. Systematic investigations against limited areas and other aspect ratios are not found. In this study, we compute percolation thresholds with various species movement ability on maps with a variety of sizes and aspect ratios by a percolation threshold analysis software Path.
The results show that the habitat area ratio of P90 or P99 should be selected to replace the traditional percolation threshold Pc in the limited area situations. Therefore, it can estimate thresholds more reasonably under limited areas to avoid underestimations. About the aspect ratio on the percolation thresholds, this study found that the deviations of percolation thresholds are increased with larger aspect ratios and the deviation ratios are increased with larger species movement ability. This study extends our understanding of the percolation threshold phenomenon on neutral landscapes. The results can be used as an reference baseline in ecological conservation and habitat restoration.
|
|---|
