摘要
中纬度干旱半干旱草原是我国的主要地表类型之一,正在面临着严重的荒漠化问题。选择浑善达克沙地东部为研究地区,利用LandsatTM和ETM+资料对该地区的植被覆盖情况进行分析。在所选的4个年度中,以1996年的NDVI值为最高(0.67),1998年略次之(0.65),1987年居中(0.47),而2001年为最低,仅0.33。水分是决定干旱半干旱地区植被生长状况的关键因子。无论是年降水还是7、8月降水,与9月的NDVI都基本上呈现了一种线性关系。气温对NDVI的影响不明显。反映地表与植物冠层表面温度的热红外亮温经常与区域内的NDVI分布基本呈反相关。少数地区,特别是一些本身植被状况较差、生态相对更为脆弱的地区,植被遭到破坏后,即使在保证降水增加的情况下也不能在短时间内恢复。比较1996和1998年,荒漠化面积增长呈现出明显的上升趋势。2001年是严重干旱年,区域平均NDVI极低,但却有7.5%的地区出现NDVI增加。这一逆向变化可能与中央和地方政府于2000年启动的一系列沙源治理项目和禁牧规定有直接关系。由此说明,除了降水这一关键自然因子之外,人类活动也对干旱半干旱草原生态的恶化或恢复起着非常重要的作用。
The mid-latitude arid and semi-arid area is one of the major surface types in China, and is facing the serious desertification hazard. Landsat Thematic Mapper data were used in this paper to monitor the vegetation cover change in east part of the Hunshandake sandy land, a semi-arid region in Inner Mongolia Autonomous Region. Combined with the monthly rainfall and air temperature data, the possible affecting factors are discussed. The NDVI in middle September are 0.47, 0.67, 0.65 and 0.33 in 1987, 1996, 1998 and 2001, respectively, which highly correlated both with the annual mean rainfall and precipitation of July and August, indicating moisture is one of the most important factors affecting vegetation condition in arid and semi-arid region. The air temperature shows little effect on NDVI, but the region with higher NDVI often associatted lower radiative temperature derived from TM band 6. There are some area showed vegetation degradation which could not be recovered in a short time of period, most of them located in poor vegetated areas. And the degraded area is increasing from 1996 (3.8%) and to 1998 (6.0%). The vegetation condition shows improvement in 2001, and this may be associated with the effort made by Chinese government to improve the ecological and environment situation of this region. This indicates that anthropogenic activities is another improtant factor affecting the NDVI in arid and semi-arid regions, especially in the ecologically more sensitive areas.
出处
《遥感技术与应用》
CSCD
2003年第6期353-359,共7页
Remote Sensing Technology and Application
基金
国家自然科学基金重大项目"IMGRASS"(No49790020)支持。
