Plant growth strategy determines the magnitude and direction of drought‐induced changes in root exudates in subtropical forests

• Published in: Global change biology 2023-06, Vol.29 (12), p.3476-3488
• Main Authors: Jiang, Zheng, Fu, Yuling, Zhou, Lingyan, He, Yanghui, Zhou, Guiyao, Dietrich, Peter, Long, Jilan, Wang, Xinxin, Jia, Shuxian, Ji, Yuhuang, Jia, Zhen, Song, Bingqian, Liu, Ruiqiang, Zhou, Xuhui
• Format: Article
• Language: English
• Subjects: amino acid; Amino acids; Amino Acids - analysis; Amino Acids - metabolism; Climate change; Climate prediction; Components; Direction; Drought; Droughts; Ecosystem; Environmental impact; Extreme drought; Extreme values; Exudates; Exudates and Transudates - metabolism; Exudation; Forest ecosystems; Forests; Growth rate; Infections; Microorganisms; Morphology; Mycorrhizae - metabolism; mycorrhizal infection; organic acid; Organic acids; Organic Chemicals - analysis; Plant Exudates - analysis; Plant Exudates - metabolism; Plant growth; Plant Roots - metabolism; Plant species; Rhizosphere; root exudation; root morphological traits; Roots; Saccharides; Soil - chemistry; Soil ecology; Soil properties; subtropical forests; Sugar; Sugars - analysis; Sugars - metabolism; Symbiosis; Terrestrial ecosystems; Throughfall; tree growth; Trees; Tropical forests
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.16685

Root exudates are an important pathway for plant–microbial interactions and are highly sensitive to climate change. However, how extreme drought affects root exudates and the main components, as well as species‐specific differences in response magnitude and direction, are poorly understood. In this study, root exudation rates of total carbon (C) and its components (e.g., sugar, organic acid, and amino acid) were measured under the control and extreme drought treatments (i.e., 70% throughfall reduction) by in situ collection of four tree species with different growth rates in a subtropical forest. We also quantified soil properties, root morphological traits, and mycorrhizal infection rates to examine the driving factors underlying variations in root exudation. Our results showed that extreme drought significantly decreased root exudation rates of total C, sugar, and amino acid by 17.8%, 30.8%, and 35.0%, respectively, but increased root exudation rate of organic acid by 38.6%, which were largely associated with drought‐induced changes in tree growth rates, root morphological traits, and mycorrhizal infection rates. Specifically, trees with relatively high growth rates were more responsive to drought for root exudation rates compared with those with relatively low growth rates, which were closely related to root morphological traits and mycorrhizal infection rates. These findings highlight the importance of plant growth strategy in mediating drought‐induced changes in root exudation rates. The coordinations among root exudation rates, root morphological traits, and mycorrhizal symbioses in response to drought could be incorporated into land surface models to improve the prediction of climate change impacts on rhizosphere C dynamics in forest ecosystems. Extreme drought significantly decreased root exudation rates of total C and sugar, and amino acid but increased root exudation rate of organic acid. Trees with relatively high growth rates were more responsive to drought in terms of root exudation rates compared with trees with relatively low growth rates.