Comparison of ecological significance of landscape diversity changes in karst mountains:a case study of 4 typical karst area in Guizhou Province

Karst rocky desertification is the kind of typical land degradation in Southwest China.But,only a few studies were focused on the landscape diversity of karst mountains.The ecological significance of landscape diversity resulted from land use/land cover will be future research field in karst mountains,due to obvious landscape heterogeneity and various landscape spatial pattern changes.In this paper,the spatial distribution of landscape diversity index in four typical karst sites,Guizhou Province,such as Wangjiazhai,Houzhaihe,Huajiang gorge and Maolan,were analyzed using of high resolution aerial photos and satellite images of 1963 and 2004 through 100m×100m grid unit.Furthermore,land degradation maps of 4 areas are combined with landscape diversity index spatial distribution maps to explain the significance of ecological diversity index.The results showed that:(1) In the Maolan,Houzhaihe and Huajiang gorge,the value of landscape diversity index declined with the increase of distance from the settlements.But this number value decreased first,then increased in 1963 and in 2004 with increasing distance from the settlements respectively in WangJiazhai.(2) The landscape matrix is forest in Maolan.The conversion of slope arable land to forest,shrub and grassland make the landscape fragmentation decrease in Houzhaihe.Therefore,the decrease of the diversity index showed that,in fact,the eco-environment was moderately recovered in the Maolan and Houzhaihe.At the same time,in the Huajiang gorge,the diversity of land use/land cover increased gradually,the karst rocky desertification has being replaced by forest and shrub patches,the increased diversity index shown that vegetation recovered slightly in this region.But the increase of the landscape diversity also showed ecological restoration in karst fengcong and hill slope,Wangjiazhai.(3)The changes of landscape diversity in study sites can′t simple directly contact with ecological change being better or worse.The evolving trend of karst rocky desertification could be identified by using of landscape indexes only when the landscape matrix of karst mountains could be distinguished from each other accurately.