Drivers and Environmental Impacts of Vegetation Greening in a Semi-Arid Region of Northwest China since 2000

Zhenzong Wu,Yifei Gao,Jian Bi

doi:10.3390/rs13214246

Abstract

The dynamics of terrestrial vegetation have changed a lot due to climate change and direct human interference. Monitoring these changes and understanding the mechanisms driving them are important for better understanding and projecting the Earth system. Here, we assessed the dynamics of vegetation in a semi-arid region of Northwest China for the years from 2000 to 2019 through satellite remote sensing using Vegetation Index (VI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS), and analyzed the interannual covariation between vegetation and three climatic factors—air temperature, precipitation, and vapor pressure deficit (VPD)—at nine meteorological stations. The main findings of this research are: (1) herbaceous land greened up much more than forests (2.85%/year vs. 1.26%/year) in this semi-arid region; (2) the magnitudes of green-up for croplands and grasslands were very similar, suggesting that agricultural practices, such as fertilization and irrigation, might have contributed little to vegetation green-up in this semi-arid region; and (3) the interannual dynamics of vegetation at high altitudes in this region correlate little with temperature, precipitation, or VPD, suggesting that factors other than temperature and moisture control the interannual vegetation dynamics there.

Highlights

We used the growing season mean vegetation greenness to investigate the interannual dynamics of vegetation activity in our study area, and their relationship with climatic factors, such as air temperature, precipitation and air humidity
Because trees were planted during the development of the Lanzhou New District, the growing season NDVI there is higher than that of the surrounding areas, which are mostly covered by grasslands
Our research shows that an increase in vegetation greenness was accompanied by a change in temperature, and this implies the increase in ecosystem water use efficiency, because of the higher temperature sensitivity of GPP relative to ET, as suggested in [59]