岩溶山区景观多样性变化的生态学意义对比——以贵州四个典型地区为例

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

岩溶石漠化是中国西南典型的土地退化,但关于岩溶山区景观多样性的研究还不多见。岩溶山区景观异质性强,景观格局空间差异大,岩溶山区土地利用/土地覆被变化引起的景观多样性变化,其生态学意义有何差异,值得开展研究。采用高分辨率的航片和遥感影像,以100m×100m网格为单元,分析了贵州省王家寨、后寨河、花江和茂兰4个典型岩溶地点的景观多样性指数在1963年和2004年的空间分布。把4个研究地点景观多样性指数空间分布图与其土地退化图结合起来,对比其多样性指数变化与土地退化和生态恢复的关系。结果表明:(1)茂兰、后寨河和花江多样性指数都表现出随距聚落距离增加而减小的趋势,王家寨1963年和2004年则表现出随距聚落距离增加,多样性指数先减小后增加。(2)茂兰地区以森林为基质,后寨河地区坡耕地退耕为林、灌、草地,土地利用方式单一,景观破碎化程度降低;因此,茂兰、后寨河地区多样性指数的降低表明该地区生态实质上有所恢复;花江地区土地利用/土地覆被逐渐向多样化方向发展,石漠化景观逐渐被林灌斑块代替,多样性指数升高表明该地区植被有所恢复;王家寨地区峰丛坡地多样性指数增加表示生态有所恢复。(3)研究地点多样性的升、降不能简单地与生态变好、变差直接联系。只有正确区分岩溶地区的景观基质,才能准确运用景观指数分析石漠化土地的变化趋势。

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.