陕北农牧交错带沙漠化土地时空变化特征分析

利用1986年、1993年及2003年3期Landsat TM遥感影像,在建立目视解译标志的基础上,借助地理信息系统技术,对陕北农牧交错带1986—2003年土地沙漠化时空动态变化特征进行分析。结果表明:陕北农牧交错带沙漠化土地重心整体向东北方向偏移了11 843.43 m,面积减少了206 655.21 hm2,表明该区沙漠化面积扩大的态势得以控制并趋于减少;沙漠化程度明显减轻,严重、重度沙漠化土地面积逐渐减少,转化为中度和轻度沙漠化,但在区域气候趋于暖干的情况下,面临着沙漠化发展的潜在危险;同时,近17 a来有近291 826.1 hm2非沙漠化土地变为沙漠化土地,沙漠化速度为17 166.2 hm2·a-1,以草地、耕地、林地等土地沙化现象较严重,土地沙漠化的形势仍然较严峻。

Spatial-temporal Change Characteristics of Sandy Desertified Lands in Agro-pasture Interlacing Zone in Northern Shaanxi

Based on technologies of the RS and GIS, the desertification dynamics of agro-pasture interlacing zone in northern Shaanxi of China from 1986 to 2003 was monitored through three sets of the multi-temporal remote sensing data of TM, acquired in 1986 , 1993, and 2003. The results showed that the centroid of desertified lands had moved 11 843.43 m towards the northeast and the area had decreased by 206 655.21 hm2. This indicated that the status of the desertification development had been basically controlled in the study area and tended to be decreased. The degree of desertification had mitigated evidently for the primary desertified lands, in which the severe desertified lands and heavy desertified lands gradually changed into moderate deseritifed lands or slight desertified lands. Even so, the potential danger of land desertification still exists under regional climate warming, for example, there were 291 826.1 hm2 desertification lands that were transformed from non-desertified lands in the recent 17 years, and the desertification rate was 17 166.2 hm2.a-1. Desertification mainly occurred in grassland, arable land and forest land. The status of sandy desertification in argo-pasture interlacing zone in northern Shaanxi is still serious.