Diverse responses of vegetation to hydroclimate across temporal scales in a humid subtropical region

Study region: Guangdong Province, South China. Study focus: With evident climate and land use changes, concerns have arisen regarding the challenges for land and water management brought by alterations of the vegetation-hydroclimate relationships. Here we characterized the relationships under contrasting dryness conditions in Guangdong province of China during 2002-2015 based on multiple datasets, with a focus on forests and crops, to identify the controlling roles of water and energy in vegetation growth. New hydrological insights: An increasing trend of annual vegetation and water availability, and diverse seasonal characteristics were revealed in dry and wet years. GPP was higher while NDVI and WUE were lower in dry years than wet years. Intra-annual NDVI and GPP were positively and WUE was negatively related to both water (TWS) and energy (ETp, Ta and Rs) factors. Linear regression shows that the correlation between TWSA and NDVI/GPP was stronger than that between atmospheric factors and NDVI/GPP at the annual scale, while the impact of the atmospheric factors on NDVI/GPP was stronger at the monthly scale. That is, water plays a dominant role in vegetation growth in the long term, while energy is more important in the short term. Different responses of NDVI and GPP to hydroclimate may lie in the GPP estimation algorithms. This study enhances our understanding of plant-water-energy interactions in the humid subtropical environment under contrasting dryness conditions.

Automated summary

This study in Guangdong Province, South China looks at the relationships between vegetation, water, and energy under contrasting dryness conditions. It reveals increasing trends in annual vegetation and water availability in dry and wet years, with different seasonal characteristics. Water plays a dominant role in long-term vegetation growth, while energy is more important in the short term.