Analysis of grassland degradation of the Tibet Plateau and human driving forces based on remote sensing

Maqu is a typical ecologically fragile area in the Tibetan Plateau, and is very sensitive to the impacts of various natural and human factors. To elucidate the reasons for grassland degradation and achieve sustainable utilization of grassland resources in Maqu, it is important to analyse the influences of various human factors on grassland degradation, and the underlying mechanisms. We used MODIS-EVI data and related social statistics from 2004 to 2013 to detect the temporal patterns of grassland degradation in Maqu. The distribution of grassland degradation gradually moved from the northwest at high altitudes to the southeast at low altitudes in Maqu. We used quantitative and qualitative methods to analyse the impact of human factors on various spatial differences in grassland degradation. We found that: 1) The impact of human activities on grassland degradation was relatively large, and the inter-annual rate of change in grassland vegetation where the distance to settlements of herders was 1-3 km was relatively high, and degradation was particularly serious near settlements after implementation of the “pastoral settlement project” in Maqu in 2008; 2) The intensity of use of grassland resources was the primary reason for degradation; overgrazing and high livestock density in various areas was significantly negatively correlated with the inter-annual rate of change in grassland vegetation; 3) From the perspective of game theory, we analysed herders' motivation for overgrazing under the current popular operational mode of the joint household, and found that implementing certain policies of eco-compensation and strengthening supervision could change their game strategy, and ultimately achieve a “do not increase grazing capacity” as the optimal strategy of the new “Nash equilibrium”; 4) Through field surveys, we found that herder production style and life style changed in recent years; implementation of housing projects for herders, construction of roads and other infrastructures, fencing, and rodent infestation, among other factors, seriously damaged grassland vegetation in Maqu.