Institute of Atmospheric Physics, Chinese Academy of Sciences
干旱半干旱区是我国的生态环境比较脆弱的地区。伴随着气候变化和人类活动的加剧，近几十年该区域植被正发生着显著的变化，然而，至今还缺乏对植被变化原因的足够认识。本文基于GLASS (Global Land Surface Satellite)叶面积指数(LAI)、CRU(Climate Research Unit)气温和降水数据，采用相关系数法及残差分析法研究了1982～2017年中国干旱半干旱区植被的时空变化特征，并分析了气温、降水及人类活动对LAI变化的相对贡献。结果发现：1)干旱半干旱区植被显著改善，仅局部地区有所退化，且植被改善在夏季最为明显；2)研究区绝大部分地区植被与气温和降水均呈正相关关系，气温对植被的影响主要表现在趋势变化上，而降水的影响则主要表现在年际变化上；3)春、夏季气温和夏季降水对干旱半干旱地区植被生长的同期影响显著，而在新疆北部和内蒙中部地区，植被对气候因子有季节尺度的滞后响应；4)植被变化受到人类活动和气候变化的共同作用，不同地区植被变化的主导因子不同。在植被改善地区，气候因子的贡献率约为59%，人类活动的贡献率约为41%；而植被退化地区，气候因子的贡献率约为-51%，人类活动贡献率约为-49%。总的来说，近几十年来我国北方干旱半干旱区植被已发生了显著变化，该变化是气温、降水和人类活动多因素综合影响的结果。
Arid and semi-arid areas are ecologically fragile regions in China. With the intensification of climate change and human activities, vegetation in this region is undergoing significant changes in recent decades. However, there is still a lack of sufficient understanding of the causes of vegetation change. Based on the GLASS(Global Land Surface Satellite) leaf area index(LAI) and CRU(Climate Research Unit) temperature and precipitation data, this paper studies the temporal and spatial variation characteristics of vegetation in arid and semi-arid areas of China from 1982 to 2017 by using correlation coefficient method and residual analysis method, and analyzes the relative contributions of temperature, precipitation and human activities to LAI changes. The results showed that: 1) Vegetation in most arid and semi-arid areas was significantly improved, and the vegetation improvement was more obvious in summer. 2) Vegetation is positively correlated with temperature and precipitation in most areas of the study area. The influence of temperature on vegetation is mainly manifested in the trend change, while the influence of precipitation is mainly manifested in the interannual change. 3) The simultaneous effects od spring and summer temperature and summer precipitation on vegetation growth in arid and semi-arid areas are significant, while in northern Xinjiang and central Inner Mongolia, vegetation has seasonal lag effect responses to climate factors. 4) Vegetation change is affected by human activities and climate change, and the dominant factors of vegetation change in different regions are various. In the vegetation-improved area, the contribution rate of climate factors is about 59%, and human activities is about 51%; and in vegetation-degraded areas, the contribution rate of climate factors is about -51% and human activities is about -49%. In general, the vegetation in arid and semi-arid areas of northern China has undergone significant changes in recent decades, which is the result of combined effects of temperature, precipitation and human activities.