不同岩性背景下土壤侵蚀与石漠化关联性分析

Effect of lithology background on the correlation between soil erosion and rock desertification

喀斯特地区土壤侵蚀与石漠化问题备受关注,为了定量分析不同岩性下土壤侵蚀与石漠化的关联性,为研究区优化生态环境提供决策依据,以贵州省沿河县为例,以Landsat遥感影像、1∶5000地形图、岩性和石漠化为基础数据,采用监督分类方法、表面分析和栅格计算,提取出土壤侵蚀的各项指标因子。对不同岩性背景下土壤侵蚀与石漠化关联性分析,结果显示:(1)沿河县石漠化面积为284.44 km2,占全县国土面积的11.52%。已发生石漠化等级以轻度、中度、强度较显著;土壤侵蚀面积为1838.97 km2,占全县总面积的74.48%,已经发生土壤侵蚀等级以轻度、中度、强度侵蚀为主。(2)灰岩与碎屑岩互层和连续性白云中,石漠化与土壤侵蚀发生面积较显著,分别占石漠化与土壤侵蚀面积的57.99%和50.45%。(3)非碳酸盐岩、灰岩夹碎屑岩、灰岩与白云岩混合、灰岩与碎屑岩互层、连续性白云岩和石灰岩上,石漠化等级与土壤侵蚀程度在潜在和轻度呈负相关、轻度和中度石漠化内呈正相关、中度和极重度石漠化内呈负相关,土壤侵蚀等级与石漠化在微度和轻度侵蚀内呈正相关,在轻度和剧烈侵蚀内呈负相关,其中灰岩与白云岩混合和连续性白云岩上,石漠化等级与土壤侵蚀存在单一的负相关。

The occurrence of both soil erosion and rocky desertification in karst areas of China have attracted much attention. In order to quantify the correlation between soil erosion and rocky desertification under different lithologies and to establish a basis for optimizing the area's ecosystem, the present study investigated the correlation between soil erosion and rocky desertification in Yanhe County (Guizhou Province, China) using Landsat remote-sensing data, a 1:5000 topographic map, and both lithology and rocky desertification data. Supervised classification, surface analysis, and grid calculation were used to extract a variety of soil erosion indices. (1) Rocky desertification affected 284.44 km2 of Yanhe County, thereby accounting for 11.52% of the county's total land area, and the grade of rocky desertification was mild, moderate, and strong. Meanwhile, soil erosion affected 1838.97 km2, thereby accounting for 74.48% of the county's total land area, and the grade of soil erosion was mostly mild, moderate, and intense. (2) Both rocky desertification and soil erosion were predominant in the interbedded and continuous limestone and clastic rock, with 57.99% and 50.45% of the rocky desertification and soil erosion found in this area, respectively.(3) Non-carbonate rocks, limestone clastic rocks, limestone and dolomite mixtures, limestone and clastic interbeds, continuous dolomite and limestone, rocky desertification grade, and degree of soil erosion were all negatively correlated with mild, positively correlated with Light and moderate rocky desertification, and negatively correlated with moderate and extremely severe rocky desertification. Soil erosion grade was positively correlated with rocky desertification in Potential and Light erosion. There was a negative correlation between Light and severe erosion. Among the limestone and dolomite mixtures and continuous dolomite, rocky desertification grade was negatively correlated with the degree of soil erosion.