退耕还林对喀斯特地区土地利用景观格局影响的定量化评价

近十几年来,退耕还林(草)工程的实施改变了贵州省普定县喀斯特地区土地利用/覆被空间格局,有效地改善了该区域的生态环境质量。在遥感和地理信息系统技术的支持下,基于主成分分析方法,以1999、2003和2009年TM遥感影像数据为主要数据源,定量分析和评价退耕还林(草)工程对土地利用及景观格局特征的影响。结果表明:1)1999—2009年间,退耕还林(草)工程实施后,普定县土地利用景观格局变化呈现出土地利用面积的动态变化、景观异质性和景观结构与形状变化的特征,其中土地利用面积动态变化与景观异质性改变为整个研究区景观格局变化的主导因子。2)从面积变化上看,研究区大量耕地、裸地转化为林地、草地和建设用地,其中林地、草地和建设用地面积呈现快速增长的特征,面积分别增加了53%、50%和140%,同时耕地面积减少了133.32 km2,减少幅度明显。3)从结构与形状指数上看,区域景观斑块总数量呈上升趋势,平均斑块面积有所下降,生态系统格局呈现破碎化加剧的趋势。4)从景观异质性上看,优势组分更加多样化,景观异质性程度逐渐上升,生态景观整体趋于规整,其中林地、草地和建设用地空间更加集聚化,但耕地和裸地分布分散化,破碎度有所上升。研究结果有助于指导退化喀斯特生态系统的恢复与重建。 

Quantitative evaluation on the impact of the Sloping Land Conversion Program on landscape pattern of land use in Karst area

By the implementation of the Sloping Land Conversion Program in Puding County, which is characterized as the special Karst region, the land use/cover pattern has been confirmed to be greatly altered with the improvement of ecological environment in the region. In this study, we analyzed and evaluated the effect of the Sloping Land Conversion Program on the landscape patterns and land use types by methods of principal component analysis (PCA) based on three series of Landsat TM images in 1999, 2003 and 2009. The results showed that:1) in 1999—2009 after the implementation of the Program, the changes of landscape pattern in Puding County were characterized in dynamic variation of land use area, landscape heterogeneity, landscape structure, and shape transformation. The changes on area of land use and the landscape heterogeneity were the leading factors affecting the changes of landscape pattern of the region;2) Regarding the variation of area, conversion from farmland and bare land to forestland and grassland was the most prominent, and the area of forestland, grassland and built-up area increased rapidly by 53%,50% and 140%, respectively. At the same time, farmland decreased by 133.32 km2;3) the number of patches (NP), one of the landscape indices, was confirmed on the rise with the other index mean patch size ( MPS ) decreasing, and fragmentation of the landscape ecological system was aggravated;4) Considering landscape heterogeneity, the dominant components were more diverse, the degree of landscape heterogeneity gradually rose, and the overall characteristics of ecological landscape became more regular. Forestland, grassland and construction land were more concentrated, however farmland and bare land were more decentralized. The degree of fragmentation increased somehow. In conclusion, evaluation results provide useful guidelines for the restoration and reconstruction of degraded Karst ecosystem.