Disentangling the effects of vapor pressure deficit on northern terrestrial vegetation productivity
Ziqian Zhong, Bin He, Ying‐Ping Wang, Hans W. Chen, Deliang Chen, Yongshuo H. Fu, Yaning Chen, Lanlan Guo, Ying Deng, Ling Huang, Wenping Yuan, Xingming Hao, Rui Tang, Huiming Liu, Liying Sun, Xiaoming Xie, Yafeng Zhang
Abstract
The impact of atmospheric vapor pressure deficit (VPD) on plant photosynthesis has long been acknowledged, but large interactions with air temperature (T) and soil moisture (SM) still hinder a complete understanding of the influence of VPD on vegetation production across various climate zones. Here, we found a diverging response of productivity to VPD in the Northern Hemisphere by excluding interactive effects of VPD with T and SM. The interactions between VPD and T/SM not only offset the potential positive impact of warming on vegetation productivity but also amplifies the negative effect of soil drying. Notably, for high-latitude ecosystems, there occurs a pronounced shift in vegetation productivity's response to VPD during the growing season when VPD surpasses a threshold of 3.5 to 4.0 hectopascals. These results yield previously unknown insights into the role of VPD in terrestrial ecosystems and enhance our comprehension of the terrestrial carbon cycle's response to global warming.