ORIGINAL RESEARCH article
Front. Ecol. Evol.
Sec. Ecophysiology
Volume 13 - 2025 | doi: 10.3389/fevo.2025.1550290
Sap flow dynamics of cooccurring trees to seasonal droughts in a subtropical climate
Provisionally accepted
- College of Ecology, Lanzhou University, Lanzhou, China
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With global climate change, the frequency and intensity of extreme drought events are gradually increasing. The northern part of the Yunnan Province in China is severely affected by droughts. The region exhibits a subtropical monsoon climate, with distinct wet and dry seasons, notable differences in precipitation and uneven spatial and temporal distributions, forest in this region may be threatened by high mortality risk under climate change. Therefore, there is an urgent need to better understand the response mechanisms of trees to drought in this region to facilitate the development of relevant forest protection measurements. In this study, we selected three mixed tree species (Pinus yunnanensis, Keteleeria evelyniana, and Castanopsis delavayi) in the Pinus yunnanensis forest. We continuously monitored their stem sap flow densities via thermal diffusion sap flow instruments and simultaneously measured environmental factors, such as solar radiation, precipitation, vapour pressure deficit (VPD), and soil water moisture (SWC), to reveal the sap flow density changes in three species and their responses to environmental factors. The results of this study revealed that decreasing plant stomatal conductance and increasing nocturnal sap flow density during the dry season were drought tolerant strategies for all three plants. Plant sap flow density was significantly lower (P<0.01) and the percentage of nocturnal runoff was significantly higher (P<0.01) in the dry season than in the wet season. In addition, the exponential decay function was used to distinguish the causes of nocturnal sap flow. The nocturnal sap flow in the dry season was caused by a combination of nocturnal transpiration (En) and stem refilling activity (Re), while nocturnal sap flow in the wet season was mainly due to Re. In the future, as the drought intensity increases, the region will face increasingly serious threats, especially when the survival strategy of plant water conservation becomes particularly important.
Keywords: Subtropical monsoon climate, Seasonal drought, Sap flow density, Water regulation strategies, nocturnal transpiration
Received: 23 Dec 2024; Accepted: 23 May 2025.
Copyright: © 2025 Tang, Ding, Wang, Zhang and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Jia-Qi Tang, College of Ecology, Lanzhou University, Lanzhou, China
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