Multi-year throughfall reduction enhanced the growth and non-structural carbohydrate storage of roots at the expenses of above-ground growth in a warm-temperate natural oak forest

• Published in: Forest ecosystems Vol. 10; no. 3; pp. 100118 - 367
• Main Authors: Liu, Cuiju, Chen, Zhicheng, Liu, Shirong, Cao, Kunfang, Niu, Baoliang, Liu, Xiaojing, Gao, Xiaomin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2023; Key Laboratory of Forest Ecology and Environment,National Forestry and Grassland Administration,Ecology and Nature Conservation Institute,Chinese Academy of Forestry,Beijing,100091,China; Henan Baotianman Nature Reserve Administration,Neixiang,474350,China; Baotianman Forest Ecosystem Research Station,Nanyang,473000,China%Guangxi Key Laboratory of Forest Ecology and Conservation,College of Forestry,Guangxi University,Nanning,530004,China%Baotianman Forest Ecosystem Research Station,Nanyang,473000,China; KeAi Communications Co., Ltd
• Subjects: Carbon allocation; Climate change; Drought stress; Forest ecophysiology; Nonstructural carbohydrates; Warm-temperate forests; Forest ecophysiology; Drought stress; Climate change; Nonstructural carbohydrates; Carbon allocation; Warm-temperate forests
• ISSN: 2197-5620; 2095-6355; 2197-5620
• DOI: 10.1016/j.fecs.2023.100118

The more frequent occurrence and severer drought events resulting from climate change are increasingly affecting the physiological performance of trees and ecosystem carbon sequestration in many regions of the world. However, our understanding of the mechanisms underlying the responses and adaption of forest trees to prolonged and multi-year drought is still limited. To address this problem, we conducted a long-term manipulative throughfall reduction (TFR, reduction of natural throughfall by 50%–70% during growing seasons) experiment in a natural oriental white oak (Quercus aliena var. acuteserrata Maxim.) forest under warm-temperate climate. After seven years of continuous TFR treatment, the aboveground growth in Q. aliena var. acuteserrata started to decline. Compared with the control plots, trees in the TFR treatment significantly reduced growth increments of stems (−14.2%) and leaf area index (−6.8%). The rate of net photosynthesis appeared to be more susceptible to changes in soil water in trees subjected to the TFR than in the control. The TFR-treated trees allocated significantly more photosynthates to belowground, leading to enhanced growth and nonstructural carbohydrates (NSC) storage in roots. The 7-year continuous TFR treatment increased the biomass, the production and the NSC concentration in the fine roots by 53.6%, 153.6% and 9.6%, respectively. There were clear trade-offs between the aboveground growth and the fine root biomass and NSC storage in Q. aliena var. acuteserrata trees in response to the multi-year TFR treatment. A negative correlation between the fine root NSC concentration and soil water suggested a strategy of preferential C storage over growth when soil water became deficient; the stored NSC during water limitation would then help promote root growth when drought stress is released. Our findings demonstrate the warm-temperate oak forest adopted a more conservative NSC use strategy in response to long-term drought stress, with enhanced root growth and NSC storage at the expenses of above-ground growth to mitigate climate change-induced drought. •The DBH growth and LAI of the oriental white oak was constrained under the long-term throughfall reduction.•The TFR-treated trees allocated more photosynthates to belowground growth and NSC storage in roots.•There were the trade-offs between aboveground growth and roots biomass and NSC storage under the TFR treatment.•The conservative NSC use strategy of the oriental white oak occurred to adapt to the long-term drought.