Study On Changes Of Spatial Pattern And Habitat Of Red-crowned Cranes In Zhalong Wetland Based On GIS

Currently, humanity is suffering from a serious biodiversity crisis worldwide.The red-crowned crane is one of the world rare species, belonging to a protected animal in China. While Zhalong wetland is the largest habitat for red-crowned cranes in our country, it is significant to study changes of spatial pattern and habitat of red-crowned cranes for protection of red-crowned cranes and biodiversity.This paper is based on the nest-site data of red-crowned cranes and land use data of Zhalong Wetland from 1981 to 2012. The method combining Ripley's K improved L(d) function with local G-statistics was selected after comparing various methods of species spatial pattern. The spatial patterns of the nest sites were studied in global and local model. Meanwhile, the change characteristics of red-crowned crane habitat were studied in aspect of the landscape pattern, human disturbance and land use change.The main conclusions are as follows:(1)View from the overall change of red-crowned crane nest-sites, from 1981 to2012, the number of red-crowned cranes experienced a change process: increasereduction-stable. Distribution area of the nest sites shrank to the core area after expanding, while the mean center of red-crowned cranes moved to the northeast from southwest. Besides, the major fire occurred in 2005 had a serious impact on the spatial pattern of red-crowned cranes.(2)It is a new way and method to study population spatial distribution pattern by introducing Ripley's K improved L(d) function and the local G-statistics from the global and local level. From 1981 to 2012, the global distribution patterns of red-crowned crane nest-sites experienced a change process: random or uniformaggregated-random or uniform. while local spatial distribution patterns experienced a process: discrete-aggregated-discrete-aggregated. Change in local spatial distribution pattern is an indicator for that in global spatial pattern.(3)Through statistical analysis of landscape index, it was found that the landscape composition of red-crowned crane habitat became more and more complex,and the degree of landscape fragmentation increased in the Zhalong wetland s nearly30 years, which is main cause for changes in the spatial pattern of red-crowned cranes.Swamp is the main landscape type of red-crowned crane habitat. From 1981 to 2012,type of land using in the red-crowned crane habitat conversed mainly in this way:heavy swamp-light swamp-grass, reflecting the habitat drought phenomenon obviously. So the water recharge mode is an important measure to alleviate the problem.(4) Low disturbance and low-middle disturbance are main types of human activities influence on the red-crowned crane habitat in Zhalong wetland. The degree of human disturbance in core area has weakened, while the range of high disturbance and high-middle disturbance in the study area reduced in early and increased lately.So it is necessary to insist on ecological migration in the core area and make relevant management system persistently, strengthening the protection and management of habitat, especially the core area.