Drought effects on tree growth, water use efficiency, vulnerability and canopy health of Quercus variabilis-Robinia pseudoacacia mixed plantation

HanSen Jia; ChongFan Guan; JinSong Zhang; ChunXia He; ChangJun Yin; Ping Meng

doi:10.3389/fpls.2022.1018405

Drought effects on tree growth, water use efficiency, vulnerability and canopy health of Quercus variabilis-Robinia pseudoacacia mixed plantation

Front Plant Sci. 2022 Oct 12:13:1018405. doi: 10.3389/fpls.2022.1018405. eCollection 2022.

Authors

HanSen Jia^{1

2

3}, ChongFan Guan^{1

2

3}, JinSong Zhang^{1

2

3}, ChunXia He^{1

2

3}, ChangJun Yin^{1

2

3}, Ping Meng^{1

2

3}

Affiliations

¹ Key Laboratory of Tree Breeding and Cultivation, National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China.
² Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forest University, Nanjing, China.
³ Henan Xiaolangdi Earth Critical Zone National Research Station on the Middle Yellow River, Jiyuan, China.

Abstract

Drought-induced forest canopy die-back and tree mortality have been commonly recorded in the lithoid mountainous regions of northern China. However, the capacity of trees to regulate their carbon and water balance in response to drought remains inadequately understood. We measured tree growth, intrinsic water use efficiency (iWUE), vulnerability, and canopy health during drought events using dendrochronology, C isotope measurements, and a tree canopy health survey in a mixed plantation of Quercus variabilis and Robinia pseudoacacia. Resistance (Rt), recovery (Rc), resilience (Rs), and increased amplitude in iWUE compared to the indices 3 years before drought (iWUEr) were calculated for each species across the dominant tree (D), co-dominant tree (CD), and suppressed tree (S). Our results revealed that D and CD showed lower Rt, higher Rc, and higher iWUEr than S. After exposure to multiple sequential drought events, Q. variabilis showed an increasing trend in Rt, and R. pseudoacacia showed a decreasing trend in Rc. R. pseudoacacia exhibited a more conservative strategy towards drought, resulting in a negative S_Rt-iWUEr (slope of the linear model fitted to capture the trend between Rt and iWUEr) during drought events than Q. variabilis. For individual trees, lower Rc or positive S_Rt-iWUEr Q. variabilis and negative S_Rt-iWUEr R. pseudoacacia were more susceptible to canopy die-back. In conclusion, our study offers a new perspective for improved management practices in the design of silvicultural actions for forestry plantations in lithoid mountainous areas with increasing drought risk.

Keywords: canopy die-back; drought stress; radial growth; resistance; stable isotopes.