喀斯特山区土地利用变化对生态脆弱性的影响

Impact of Land Use Changes in Karst Mountain Area on Ecological Vulnerability

喀斯特山区作为我国四大脆弱区之一,经济发展相对落后,不合理的土地利用极易诱发和加强喀斯特山区的水土流失和生态恶化,加剧生态脆弱性。目前仍缺乏针对喀斯特地区的较为系统与完善的生态脆弱性评价指标体系,且土地利用变化对生态脆弱性影响的研究也相对较少。本文以云南省文山市为例,构建喀斯特山区生态脆弱性指标体系,运用空间主成分反演生态脆弱性,并采用重心模型和空间自相关分析探讨其空间演变规律,同时使用交叉敏感性系数探讨不同土地利用类型的转移对生态脆弱性的影响。结果表明:(1)2000—2017年文山市土地利用类型以耕地和林地为主,除未利用地、草地、林地面积减少外,其他用地面积增加;(2)2000—2017年文山市生态脆弱性以轻度、中度、重度脆弱为主,整体脆弱性变化较小,但脆弱程度加剧;(3)文山市北部生态脆弱性较高,西部脆弱性较低;且脆弱性重心整体向西北移动,成为脆弱性高-高集聚区,而西部与西南部因生态工程的实施,脆弱性高-高集聚区域面积不断减小,生态状况得以改善,成为脆弱性低-低集聚区;(4)文山市未利用地与建设用地的脆弱性较高;对生态脆弱性最敏感的土地利用变化是水域和草地、水域和未利用地的相互转移,且水域、林地、未利用地等用地类型面积变化对生态脆弱性较敏感。本研究可为进一步识别喀斯特山区不同生态脆弱区及针对不同生态脆弱区采取生态修复模式的研究提供科学依据。

Karst Mountain Areas,as one of the four most vulnerable regions in China,is relatively backward in economic development.Unreasonable land use can induce and strengthen soil erosion and ecological deterioration,which intensifies ecological vulnerability.At present,there is no systematic and perfect evaluation index system in assessing ecological vulnerability in Karst Mountain Areas,and also there are few studies focus on the impact of land use change on ecosystem balance.Taking Wenshan city,a typical Karst Mountain Area in southeast Yunnan,China as an example,this study introduced an integrated evaluation index system of ecological vulnerability based on the local geo-environmental and humanistic features in Karst Mountain Areas.A model of Spatial Principle Comment Analysis(SPCA)was used to retrieve and reverse ecological fragility;Gravity Center Analysis method and Spatial Autocorrelation method were used to investigate its spatial evolution law;Cross-sensitivity Coefficient(CCS)was referred to describe the impacts of different land use types on ecological fragility.Results show that:(1)From 2000 to 2017 the land use types in Wenshan city were mainly comprised of cultivated land and forest land.Except for the decrease of forest land,grass land and unused land,the area of other land types were increasing.(2)From 2000 to 2017 Wenshan city mainly consisted of ecological vulnerability in mild,moderate and severe level,with less overall change,but the degree of vulnerability had increased to some extent.(3)The ecological vulnerability of Wenshan city was higher in the north and lower in the west.The center of its vulnerability moved to the northwest as a whole in the period of 2000 to 2017,forming high vulnerability-high agglomeration area mostly in the northwest whereas low high vulnerability-high agglomeration in the west.Due to the implementation of ecological projects in the west and southwest for years,the remained area of high vulnerability-high agglomeration had been continuously reduced.With a noticeably improved ecological situation,it finally turned the areas into low vulnerability-low agglomeration.(4)The vulnerability of unused land and construction land was relatively high;Reciprocal transformation between water area and grassland,water area and unused land in Wenshan city were the most sensitive to ecological vulnerability.Moreover,changes in the area of water,woodland,unused land and other land types were sensitive to ecological vulnerability.This study can provide a scientific basis for the further identification of different ecological fragile areas and the study of ecological restoration models in karst mountain areas.