Spatial and Temporal Changes of Landscape Patches in Baiyangdian Wetlands,China

The changes of landscape pattern profoundly reflect effect of human activities on the ecology and environment.The spatio-tempo-ral changes of Baiyangdian wetland landscape pattern from 1987 to 2007 were studied through the analysis of remote sensing images in 1987,1999 and 2007.Variations of landscape metrics were analyzed using GIS and Fragstats3.3 software package.Results showed that:reed bed,farmland and waters were the main landscape types in Baiyangdian,and they accounted for a proportion of 86.62%～93.06% of the total area,of which the reed bed was 42.74%～58.02%.The patch numbers and density increased by 23.01%,indicating the aggravation of landscape frag-mentation.The evenness index and diversity index declined from 0.74 to 0.67,and 1.44 to 1.25,respectively.Areas of reed and cultivated land were increased significantly,by the respective 18.08% and 28.05%,while water and dry grass were reduced greatly,by 35.78% and 76.53%,respectively.Landscape fractal dimension of this region ranged from 1.05 to 1.27,demonstrating the strong human impacts.The fractal dimen-sions of the reed bed and waters were much higher,ranging from 1.27 to 1.19 and from 1.16 to 1.09,showing the largest magnitude of decrease.While the fractal dimensions of bare lands,dry grasslands and woodland were all the lowest during the studied period,indicating the intense human impacts.According to the spatio-temporal changes of dominate landscape patterns,the wetland could be divided into three parts:part G,WG and WS.The dominate types in part G and WG exhibited a changing trend from water to farmlands via the state of reed bed.While in part WS reed bed and waters were preserved due to inter-basins water transfer.Consequently,the whole water area displayed an eastward transference.Accordingly we suggest that the protection of waters,reed and other natural patches should be taken as the core objects,and disturbance to these landscapes especially that from farming,construction and domestic pollution should be controlled strictly.Additionally,in water transfer projects,the spatio-temporal characters of the wetlands should also be taken into deep consideration,in order to minimize the influence on local natural landscapes and biodiversity,further more to assure the integrity and eco-healthy of the wetland.