基于NDVI的藏北地区草地退化时空分布特征分析  

Temporal and spatial distribution of grassland degradation in northern Tibet based on NDVI

作　　者：曹旭娟 干珠扎布[1,2] 梁艳[1,2] 高清竹[1,2] 张勇[3] 李玉娥[1,2] 万运帆[1,2] 旦久罗布 

机构地区：[1]中国农业科学院农业环境与可持续发展研究所,北京100081 [2]农业部农业环境与气候变化重点实验室,北京100081 [3]北京师范大学环境学院,北京100875 [4]西藏自治区那曲地区草原站,西藏那曲852100

出　　处：《草业学报》2016年第3期1-8,共8页Acta Prataculturae Sinica

基　　金：国家科技支撑课题(2012BAC01B02);国家自然科学基金项目(31170460);西藏那曲地区与中国农业科学院合作项目资助

摘　　要：本文以藏北地区为研究区域,基于归一化植被指数(NDVI)反演草地植被盖度,以植被盖度作为判断草地退化的标准,综合计算藏北地区2000-2010年逐年草地退化指数(grassland degradation index),定量揭示藏北地区草地退化的时空分布规律。结果表明,截至2010年,藏北地区草地退化现状仍然较为严重,退化草地的面积占全区面积的58.2%。其中,重度退化和极重度退化草地面积的比例分别为19.0%和6.5%,区域草地退化指数为1.97,接近中等退化水平。分区结果显示,藏北地区中部、东部、北部草地退化情况较为严重,均处于中等退化等级,西部地区的退化情况最轻,处于轻度退化等级。分析2000-2010年藏北地区全区及各个分区的草地退化趋势表明,只有北部地区有减缓趋势;2000-2010年间与1981-1985年间对比结果显示,重度退化及极重度退化草地面积比例上升幅度较大。2000-2010年间藏北地区平均草地退化指数为1.84,草地退化等级在轻度退化到中度退化之间波动。An expansive alpine grassland ecosystem dominates the landscape in Northern Tibet,and the status of this grassland has significant implications for the major Asian rivers,and for the climate and eco-environ-ment of Tibet and the wider region.The harsh natural environment and fragile ecosystem,together with in-creasing frequency and intensity of human activities such as pastoralism,and climate change,have resulted in increasing reports of degradation of the grassland ecosystem.We used vegetation cover as main indicator of eco-system health,and with remote sensing monitoring,calculated the grassland degradation index (GDI)and e-valuated grassland degradation in Northern Tibet from 2000 to 2010.The analysis was based on the Normalized Differential Vegetation Index (NDVI)data from the Advanced Very High-Resolution Radiometer (AVHRR) with a spatial resolution of 8 km from 1981 to 1985 and from Moderate Resolution Imaging Spectroradiometer (MODIS)with a spatial resolution of 0.25 km of 2000-2010.Then,we have analyzed the temporal and spatial distribution of grassland degradation in Northern Tibet from 2000 to 2010.It was found that grassland degra-dation in Northern Tibet was still severe.The GDI was 1.97 in 2010,near to seriously degraded status.The extremely seriously degraded and seriously degraded categories occupied 6.5% and 19.0% of the study area, respectively.The moderately and slightly degraded grassland categories accounted for 15.1% and 12.1%,re-spectively.Undegraded grassland occupied 41.8% of the total grassland area in 2010.The extent of extremely seriously degraded and seriously degraded categories was greatly increased in the data from 2000-2010,com-pared with the period from 1981 -1985.However,the increase in grassland degradation in Northern Tibet from 2000 to 2010 was slight,with the mean value of the GDI being 1.84 in 2010,representing a change from light degradation to moderate degradation in Northern Tibet from 2000 to 2010.

关 键 词：草地退化 NDVI 植被盖度 藏北地区 

分 类 号：S812.6[农业科学—草业科学]