Work

Rising atmospheric CO2 outweighs elevated vapor pressure deficit in explaining increased intrinsic water use efficiency in Chinese pine

Year: 2026

Type: article

Abstract: Introduction Tree intrinsic water use efficiency (iWUE) is an important metric for carbon and water balance in forest ecosystems. Tree iWUE has widely increased due to rising atmospheric CO 2 and intensified drought. However, the dominant effects of rising atmospheric CO 2 2, vapor pressure deficit (VPD), and soil moisture on iWUE are not fully understood. Methods We developed tree-ring width, stable carbon and oxygen isotopic chronologies derived from Chinese pine ( Pinus tabulaeformis ) stands across northern China to quantify the ecophysiological responses of iWUE to atmospheric CO 2 and drought. Results iWUE was significantly correlated with atmospheric CO 2 and VPD at both dry and wet sites. Furthermore, increased assimilation rate led to increased iWUE at both dry and wet sites. Notably, the beneficial effect of atmospheric CO 2 on iWUE outweighed that of VPD in Chinese pine. Discussion Our findings highlight the dominant role of rising atmospheric CO 2 in enhancing assimilation rate and increasing iWUE of Chinese pine and will aid in defining the performance of this tree species under climate change in northern China.

Source: Frontiers in Plant Science

DOI: 10.3389/fpls.2026.1721057

Authors: Yuanqiao Li, Yunni Wang, Wenfang Xu, Jinkai Tan

Institutions: Fujian Agriculture and Forestry University, Xinjiang Academy of Forestry, Chinese Academy of Sciences, South China Botanical Garden, Shenzhen Technology University

Language: English

Topic: Plant Water Relations and Carbon Dynamics

Subfield: Global and Planetary Change

Field: Environmental Science

Domain: Physical Sciences

SDG: Climate action

Open Access status: gold

Estimated APC paid: $3,801