EVI Indicated Spatial-Temporal Variations in Vegetation and Their Responses to Climatic and Anthropogenic Factors in the Chinese Mainland Since 2000s

Abstract

Terrestrial ecosystems of China play an important role in global carbon cycle. Identifying spatial-temporal variation of vegetation and their driving forces in China is necessary. This study used recent Enhanced Vegetation Index (EVI) data (2000 to 2019) to analyze interannual changes of vegetation activity in mainland China, and examined their responses to climatic (precipitation and temperature) and anthropogenic factors (human land-use management such as afforestation, cultivation and urbanization). The results showed an increasing trend in EVI over the 20-year period, which strikingly prominent in Loess Plateau. Besides, the greening rate of mainland China over 2009 ~ 2019 was weaker than that for 2000 to 2008. The wetter and warmer climatic condition in recent 20 years is conducive to vegetation growth in mainland China. In addition, human activities, such as implementation of ecological restoration programs, construction of irrigated areas and heavy fertilizer use promote the vegetation growth in forestland and cultivated land. While the browning in some vegetated land might relate to urbanization. Although climatic and anthropogenic factors both contributed to vegetation change, our results indicated that the anthropogenic factors were the key drivers. In more than half of the significant greening or browning region (51.2%), EVI change were dominant by human activities (explain more than 60% of the significant trend). However, climate change was a dominant driver of EVI change over only 9.9% of significant greening or browning region. The findings of this study provided details of EVI variations and their mechanics in mainland China, which can provide useful information for government organizations.

Keywords: vegetation variation, climate change, human activities, the Chinese Mainland