铜仁市万山喀斯特地区石漠化演变及其对土地利用变化的响应

The evolution of rocky desertification and its response to land use changes in Wanshan Karst area, Tongren City, Guizhou Province, China

为了解万山典型喀斯特地区石漠化演变与土地利用变化的相关性,采用监督分类方法解译2000、2010年和2015年万山区土地利用现状图,与构建的岩性及同期石漠化叠加分析,探明每种岩性土地利用分布特征和每种土地利用类型石漠化发生百分比,以此揭示各土地利用类型对石漠化影响的程度。结果表明:从岩性空间上看,林地(有林地、灌木林地)在非碳酸盐岩组合上分布面积最广,其中林地面积最多为142.89 km2,在灰岩与白云岩混分布最少,面积最少为13.37 km2;2005-2010年的石漠化在灰岩与白云岩混上变化最大,变化速率为-1.87 km2·a-1,其中,在灰岩与白云岩混上发育的轻度、中度石漠化比例最高,白云岩夹碎屑岩上发育的重度石漠化比例最高,整体上来说石漠化更容易在碳酸盐岩(灰岩与白云岩混、白云岩夹碎屑岩)上产生。根据典型石漠化的分级情况和各地类石漠化分布的占比得出,研究区发生石漠化的土地类型主要为旱地和林地(有林地、灌木林地),这两类土地类型对石漠化的贡献和响应最大,两地类石漠化发生比例最高分别为20.87%和4.32%,而旱地主要以发生轻度石漠化为主,且发生机率高达93.61%。研究结果为研究区内石漠化发生区域的定位和治理提供了科学参考。

To understand the correlation between the evolution of rocky desertification and land use changes in the Wanshan Karst area,this study used the supervised classification method to interpret the land use map of Wanshan District,Tongren City,Guizhou Province,China in 2000,2010,and 2015,as well as the lithology and the contemporaneous rock desert.The superposition analysis aimed to determine the distribution characteristics of each lithology land use,and the percentage of each type of land use that is experiencing rocky desertification,in order to reveal the degree of response of every land use type to rocky desertification.The results showed that from the lithological space,the forest land(as well as shrub land)had the widest distribution area on non-carbonate rocks.The forest land area was up to142.89 km2.In contrast,limestone and dolomite mixed areas were the least,with an area of at least 13.37 km2.Rocky desertification had the largest change in the mixed limestone and dolomite areas in 2005-2010,and the rate of change was-1.87 km2·a-1.Of these,the proportion of mild and moderate rocky desertification in limestone and dolomite areas was the highest,and the rocky desertification that developed on the dolomite clastic rock was the most severe example.Rocky desertification was more likely to occur in carbonate rock areas(Graystone mixed with dolomite,dolomite clastic rock).Analysis of the composition of land that had undergone rocky desertification:Based on the classification of typical rocky desertification and the distribution of rocky desertification in various areas,it was concluded that the land types that had experienced rocky desertification in the study area are mainly dry land and forest land(as well as shrub land).These two types of land had the greatest contribution and response to rocky desertification.The highest occurrence ratio of rocky desertification in these two land types was 20.87%and 4.32%,respectively,whereas the dry land was mainly caused by mild rocky desertification.Additionally,the probability of occurrence was as high as 93.61%,which would provide a reference value for the regionalization of rocky desertification in the study area and better and faster management.