长江源区沙漠化及其景观格局变化研究

以1975年的MSS数据、1990年和2005年的TM数据以及2000年的ETM数据为数据源,基于遥感与地理信息系统技术,获得了长江源区1975-2005年间沙漠化的发展特征,并采用景观指数运算软件FRAGSTATS3.3对长江源区沙漠化土地的景观格局变化进行了分析。研究发现,在1975-1990年间,沙漠化土地的增速为61.72 km2·a-1;在1990-2000年间,沙漠化土地的增速为4.54 km2·a-1;在2000-2005年间快速增加,增速高达341.43 km25a-1。在沙漠化发展的同时,长江源区沙漠化土地的景观格局变化也非常显著,在1975-2005年间,沙漠化土地发生了严重的破碎化,斑块形状趋于复杂;在1990-2000年间,沙漠化土地出现了连片的现象,沙漠化土地的破碎度有所下降;在2000-2005年间,沙漠化土地破碎度增加。

Land Desertification and Landscape Pattern Change in the Source Region of Yangtze River

Four sets of remote-sensing data were used in this study: Landsat multi-spectral scanner(MSS) imageries acquired in 1975 with an 80-m spatial resolution,Enhanced Thematic Mapper(ETM) imageries acquired in 2000 with a 30-m resolution,and Thematic Mapper(TM) imageries acquired in 1990 and 2005 with a 30-m spatial resolution.Based on the technology of remote sensing and geographic information system,the characteristics of land desertification in the source region of Yangtze River from 1975 to 2005 were acquired.Result showed that the area of desertification lands increased by 2 678.43 km2 from 1975 to 2005,accounting for 8.78% of the total area of desertification land in 1975.The increase rates during 1975-1990,1990-2000 and 2000-2005 were 61.72 km25a-1,4.54 km25a-1 and 341.43 km25a-1,respectively.Furthermore,landscape software Fragstats 3.3 was used to analyze landscape pattern of the desertification lands.It was found that the landscape pattern changed significantly.The fragmentation degree of desertification land increased rapidly between 1975 and 1990,decreased slightly between 1990 and 2000,and increased again between 2000 and 2005.