Effects of Vegetation Changes and Multiple Environmental Factors on Evapotranspiration Across China Over the Past 34 Years

Documenting the spatiotemporal changes in vegetation cover and hydrological cycle of the Earth system and understanding how they interact are important especially under climate warming. In this research, we quantified the changes in vegetation and evapotranspiration (E) across China during 1982-2015 and then revealed the complex relationships in climate-vegetation-evapotranspiration system. Results show that the upward trend in vegetation leaf area index (LAI) during 2000-2015 (an increase of 0.95% per year) was almost 8 times the trend during 1982-1999. The zones of the Loess Plateau and the Three-North Shelter Forest Program are the most notable areas for LAI increases between these two periods, with increases of 11.65% and 2.87%, respectively. Increased LAI, along with the warming climate, has accelerated E across China in the past several decades, and the annual increase in the E rate was 0.34% (1.34 mm year(-1)) during 1982-1999 and 0.40% (1.62 mm year(-1)) during 2000-2015. The zones of the Loess Plateau and the karst landform are the most notable areas for transpiration increases, with individual increases of 10% and 5%, respectively. In general, the dominant causes for evaporation changes across all of China are temperature and precipitation, while the main reasons for transpiration changes include temperature, LAI, and sunshine duration. This study improves our understanding of the relationships within the climate-vegetation-evapotranspiration system and provides important support for future ecological policies across China.