基于时间序列遥感数据的西藏山南地区植被覆盖变化特征分析

基于2002-2013年长时间序列MODIS-NDVI遥感数据,采用Mann-Kendall检验、多元回归分析、GIS空间分析等方法,分析了西藏山南地区植被覆盖的时空变化特征,并结合地表温度和降雨量数据,采用植被-气候时空关系模型,定量分析了气候变化和人类活动对植被覆盖变化的相对贡献率。结果表明:(1)2002-2013年山南地区年均植被覆盖度在60.16%～63.26%波动,山南地区的高、中高、中等、中低、低植被覆盖度区域占比分别为40.96%、14.07%、14.93%、14.16%、15.88%。(2)近12年来,西藏山南地区植被覆盖的变化趋势大体处于平稳状态,植被覆盖度下降区域占总面积的11.8%,植被覆盖度上升区域占3.18%。(3)气候变化是影响植被生长的决定性因素,但人类活动可在短期内加快植被变化速率。在植被覆盖度下降区域,气候变化和人类活动的贡献分别为93.75%和6.25%;在植被覆盖度上升区域,气候变化和人类活动的贡献分别为76.57%和23.43%。

Analysis on Vegetation Coverage Change in Shannan,Tibet, China Based on Remotely Sensed Data

The paper uses multi-temporal remotely sensed data from 2002 to 2013 to analyze the temporal-spatial changes of vegetation coverage in Shannan, Tibet, China by applying Mann-Kendall test, multivariate regression analysis, and geographical information system (GIS) spatial analysis. Next, land surface temperature combined with precipitation information are input to a vegetation-climate temporal-spatial model for quantitatively estimating contribution rates of climate change and human activities to vegetation coverage. The results demonstrated that the average annual vegetation coverage rates were 60.16%-63.26% from 2002 to 2013.The areas of high, mid-high, moderate, mid-low, and low coverage rates covered 40.96%, 14.07%, 14.93%, 14.16%, and 15.88% of the studied area, respectively. The tendency of the vegetation coverage change in the studied area had been stable for the 12 years, the decreased and increased vegetation coverage rates accounted for 11.8% and 3.18%, respectively; The climate change acted as the dominant factor for influencing vegetation cover change. However, human activities can accelerate the vegetation change rate, reduce or enlarge the vegetation coverage areas in a short time period. Thus, the contribution rates of climate factors and human activities to vegetation cover decrease were 93.75% and 6.25%, and the contributionrates of climate factors and human activities to vegetation cover increase were 75.57% and 23.43%, respectively.