Management practices should be strengthened in high potential vegetation productivity areas based on vegetation phenology assessment on the Qinghai-Tibet Plateau

Climate change and human activities have severely affected the structure and function of vegetation on the Qinghai-Tibet Plateau (QTP). Management practices have contributed to vegetation growth on the QTP, yet the response of vegetation productivity to management during the growing season remains unclear. Here, a fitted sixth-degree polynomial function was used to extract phenology-based vegetation productivity, which was quantified as the integrated normalized difference vegetation index (INDVI) over the length of the season during 2000-2019. Additionally, a new management practice intensity indicator was established to quantify the degree of ecological project and policy effectiveness on vegetation productivity. Three main results were obtained: (1) On a pixel-by-pixel basis, phenology-based vegetation productivity can avoid the impact of start-of-season (SOS) and end-of-season (EOS) variations. Vegetation productivity increased over 66% of the area of the QTP during 2000-2019, and the area with a significant increasing trend in vegetation productivity accounted for 9.15% of the QTP, including 5.65% in grassland and 0.23% in cultivated land. (2) Areas of increased vegetation productivity, grassland productivity, and cultivated land productivity affected by the positive impact from climate change accounted for 23.76%, 16.61%, and 0.31%, respectively, while they accounted for 41.29%, 28.10%, and 0.59% for human activities, respectively. (3) The regions of high-level management practice intensity accounted for 26.51% of the QTP but only 2.57% and 0.03% of grassland and cultivated land productivity, respectively. The regions of decreased grassland productivity still accounted for 21.85% of the QTP. Therefore, improving vegetation management practice intensity on grassland can increase regional vegetation productivity. These findings can provide effective guidance for regional vegetation management.

Automated summary

This study reveals that climate change and human activities have significantly impacted the structure and function of vegetation on the Qinghai-Tibet Plateau (QTP). Management practices and climate change have both contributed to the increase in vegetation productivity, but the effect of high-level management practices on vegetation productivity is relatively small, and there are still areas where grassland productivity has decreased.