1982-2014年藏北地区植被NDVI变化特征及驱动因素

Change in NDVI of northern Tibet and root cause analysis from 1982 to 2014

近5年草原生态补偿项目的实施,那曲地区的植被长势发生了一定的变化。利用1981-2014年GIMMS、MODIS-NDVI及同期气象、社会统计资料分析了那曲地区植被时空变化及气象因子、人类活动对其的影响。结果表明,近34年来,那曲地区植被年际变化呈不显著波动变化(P>0.05);年代变化呈显著的周期性波动上升趋势(P<0.05)。34年来那曲地区植被整体趋于稳定态势,局部有减少和改善趋势,研究区57.82%的区域植被呈稳定状态,32.84%的区域呈轻微改善趋势,轻微退化区占14.06%,显著退化和改善区约占7%,退化区主要集中在那曲东部和东南部各县,稳定区在中西部和北部各县、部分区域甚至有所改善。降水量、气温及牲畜数量的变化是引起那曲地区植被趋于空间分布不均的主要原因。

Vegetation growth in Nagqu exhibited an marked variation in status in the last 5 years under the grassland reform ecological compensation project.GIMMS,MODIS-NDVI,meteorological observations,and data on social statistics from 1981-2014 have been used to investigate spatial and temporal variations in vegetation along with the effect of meteorological factors and human activities on vegetation distribution.The results showed that interdecadal variations in vegetation exhibited a periodic increasing tendency,while interannual variation did not change substantially in the past 34 years.The trend showed by vegetation in most parts of Nagqu indicated a stable variation,and the areas constituted 57.82%of the total region;areas with slight improvement and decrease constituted 32.84%and 14.06%,respectively,and areas with significant variation represented 7%.Areas with serious degradation were mainly concentrated in the eastern and southeastern counties of Nagqu,while stable areas were situated to the west of the middle region and northern counties;vegetation in certain areas even tended to improve.Variations in precipitation,air temperature,and livestock density constitute the main reason for the uneven spatial distribution of vegetation in Nagqu.