滇东南典型喀斯特山区石漠化时空演变及生态敏感性评价

Spatio-temporal Evolution and Ecological Sensitivity Evaluation of Rocky Desertification in Typical Karst Mountainous Areas of Southeast Yunnan Province

石漠化作为滇东南地区最为严重的生态环境问题,制约当地可持续发展。生态敏感性评价是分析区域生态环境稳定性的主要方法之一,可为典型石漠化地区生态环境修复和治理提供依据。为探究石漠化地区生态敏感性变化情况,获取预防和治理岩溶区生态环境问题的有益信息,以西畴县为例,基于Google Earth Engine平台分析2000-2020年西畴县石漠化时空演变过程,结合石漠化、水土流失及生境质量因子,通过层次分析法和熵权法的组合赋权法评估研究区生态敏感性。结果表明,1)2000-2020年,西畴县石漠化状况整体呈稳中向好的恢复趋势,无石漠化面积增加275 km^(2),占比增加18.3%,各等级石漠化面积下降0.281%-7.49%。2)空间上,西畴县各等级石漠化均向无石漠化转变,其中磨合、三光、长箐等小流域最为明显,反映出部分地区石漠化治理取得显著成效。3)结合石漠化变化对岩溶区生态敏感性评价模型的构建具有重要作用。西畴县生态敏感性较高,原因有:①石漠化严重地区,植被覆盖度低,坡度大;②土地利用类型约1/4为耕地,生态敏感性较高。③降雨侵蚀力和土壤可蚀性因子较高,土壤质地易被侵蚀,造成水土流失;④越靠近道路,缓冲区等级越高,生态敏感性越高。4)西畴县2000-2020年综合生态敏感性下降,平均综合敏感性指数由4.67(中度敏感)下降至3.26(轻度敏感),尤其以莲花塘乡、柏林乡及兴街镇南部生态敏感性下降明显。

As southeast Yunnan has the most severe ecological and environmental problems,rocky desertification restricts local sustainable development.Ecological sensitivity assessment is crucial for analyzing the stability of the regional ecological environment and establishing a foundation for the restoration and management of the ecological environment in typical rocky desertification areas.To explore the variation in ecological sensitivity in rocky desertification areas and obtain helpful information for preventing and controlling ecological environmental issues in karst areas,taking Xichou County as an example,the spatiotemporal evolution process of rocky desertification was analyzed between 2000 and 2020 based on the Google Earth Engine,integrating rocky desertification factors of water and soil erosion,and habitat quality.Subsequently,ecological sensitivity was evaluated by combining the analytic hierarchy process and entropy weight methods.The results showed that 1)from 2000 to 2020,the stony desertification situation in Xichou County exhibited a stable and good recovery trend.The area without stony desertification increased by 275 km^(2),accounting for 18.3%,and the rocky desertification area decreased by 0.281%–7.49%.2)In terms of spatial patterns,all levels of rocky desertification in Xichou County changed to no rocky desertification,especially in Runhe,Sanguang,Changqing,and other small basins,reflecting remarkable effects in rocky desertification control.3)Combining the variations in rocky desertification is essential for modeling the ecological sensitivity assessment of karst areas.The ecological sensitivity of Xichou County is higher for the following reasons:(a)the vegetation cover is low with steep slopes in the rocky desertification area.(b)Approximately 1/4 of the land use is farmland,and ecological sensitivity is high.(c)Rainfall erosion and soil erodibility factors were relatively high,and the soil texture was easily eroded,resulting in soil erosion.(d)The closer to the road,the higher the buffer zone level and ecological sensitivity.4)The average comprehensive sensitivity index decreased from 4.67(moderate sensitivity)to 3.26(mild sensitivity)in Xichou County from 2000 to 2020,especially in Lianhuatang Township,Berin Township,and the southern part of Xingjie Township.This study proposes a novel evaluation of ecological sensitivity in karst areas considering the actual ecological environment and the variation in rocky desertification,which can provide a theoretical basis for further restoration and ecological environment protection in Xichou County and southeast Yunnan and is also highly applicable to other karst development areas.