藏西南高原植被覆盖时空变化及其与气候因素和人类活动的关系

研究基于MODIS-NDVI数据和气象数据，利用趋势分析、相关分析及残差分析等方法，分析了2000―2020年藏西南高原植被NDVI在不同时段的时空变化特征及气候因素和人类活动对植被NDVI的影响，结果表明：近20 a来藏西南高原植被NDVI呈增加趋势，不同时段植被NDVI增长速率存在显著差异，主要表现为秋季>生长季>夏季>全年>春季>冬季；不同时段植被NDVI的分布格局虽存在差异，但高原东部植被覆盖度明显高于西部地区；高原大部分区域植被状态基本稳定，局部明显改善，部分区域有所退化；年际尺度上，气温和降水的增加导致植被NDVI升高，季节尺度上，春季、秋季和冬季气温升高导致植被NDVI升高，降水的增加导致植被NDVI下降，夏季和生长季气温升高导致植被NDVI下降，降水升高导致植被NDVI增加；人类活动对高原大部分区域呈正面影响，局部地区呈负面影响，集中分布在半农半牧和纯牧业县区。

Spatio-temporal Variation of Vegetation Cover and Its Relationship with Climatic Factors and Human Activities in the Southwest Tibetan Plateau

Exploring vegetation cover changes in alpine regions and their influencing factors has become one of the focal issues for scholars at home and abroad. Based on MODIS-NDVI data and meteorological data, this study analyzed the spatial and temporal characteristics of vegetation NDVI in the Southwest Tibetan Plateau (SWTP) from 2000 to 2020 and the effects of climate change and human activities on vegetation NDVI by using trend analysis, correlation analysis and residual analysis. The results showed that NDVI in the SWTP has been increasing in the past 20 years. There are obvious differences in the growth rates of vegetation NDVI in different time periods mainly as follows: autumn > growing season > summer > whole year > spring > winter; although there are differences in the distribution pattern of vegetation NDVI in different time periods, the vegetation cover in the eastern part of the plateau is significantly higher than that in the western part. The vegetation status is basically stable in most areas of the plateau, with significant local improvement and degradation in some areas. On the interannual scale, the increase of temperature and precipitation led to the increase of vegetation NDVI, and on the seasonal scale, the increase of temperature in spring, autumn and winter led to the increase of vegetation NDVI, and the increase of precipitation leads to the decrease of vegetation NDVI, and the increase of temperature in summer and growing season led to the decrease of vegetation NDVI, and the increase of precipitation leads to the increase of vegetation NDVI. Human activities have a positive impact on most areas of the plateau, and a negative impact in some areas, concentrated in counties with semi-agricultural and semi-pastoralism and purely pastoralism.