Identifying ecological corridors using shortest path algorithm based on raster data
基于栅格数据和图论算法的生态廊道识别

Ecological corridor,which plays an important role in biodiversity protection,is defined as a stretch of nature mosaic that facilitates the migration of animals.Many GIS software packages use raster cost surface to identify the path of least resistance between source and destination.Limitation of these methods is that only a single path can be identified.However,ecological corridors should be more complicated and more redundant.Many alternative paths with less cost might exist in fact for animals may not choose the optimum path when moving between different habitats.In this paper,a new approach based on Spatial Analyst Tools of ArcGIS using raster data is proposed to identify the redundant routes.Firstly,the resistance cost surface moving from source to adjacent raster was defined.Secondly,the accumulated least-cost raster from both source and destination habitat to any other raster on the cost surface was evaluated.Two accumulated least-cost raster were added by raster calculation module.The value of the added raster is the accumulated least-cost which passed the current raster.Thirdly,the corridor was obtained by extracting the added raster with a certain value.Corridors of six simulated landscape patterns with different spatial autocorrelations were used to assess this procedure.The results showed that the corridors obtained by the procedure include not only the optimum path,but also some sub-optimum paths.The corridor is redundant and fit for describing the migration behavior of animals.Lastly,the identification of the ecological corridors in West Bank Pilot Planning Area of Changsha was taken as an example.The results showed that eleven key habitats existed in the study area.Corridors of twenty adjacent habitat pairs were analyzed.The results showed that all the corridors were of certain width and some of the corridors had furcation or even bypath.However,there are some bottlenecks in some corridors,which become the key zone for the ecological restoration.