Duan Honglang, Wang Defu, Zhao Nan, Huang Guomin, Resco de Dios Víctor, Tissue David T
Institute for Forest Resources and Environment of Guizhou, Key Laboratory of Forest Cultivation in Plateau Mountain of Guizhou Province, College of Forestry, Guizhou University, Guiyang, China.
Jiangxi Provincial Key Laboratory for Restoration of Degraded Ecosystems and Watershed Ecohydrology, Nanchang Institute of Technology, Nanchang, China.
Front Plant Sci. 2022 Aug 11;13:967187. doi: 10.3389/fpls.2022.967187. eCollection 2022.
Subtropical tree species may experience severe drought stress due to variable rainfall under future climates. However, the capacity to restore hydraulic function post-drought might differ among co-occurring species with contrasting leaf habits (e.g., evergreen and deciduous) and have implications for future forest composition. Moreover, the links between hydraulic recovery and physiological and morphological traits related to water-carbon availability are still not well understood. Here, potted seedlings of six tree species (four evergreen and two deciduous) were grown outdoors under a rainout shelter. They grew under favorable water conditions until they were experimentally subjected to a soil water deficit leading to losses of 50% of hydraulic conductivity, and then soils were re-watered to field capacity. Traits related to carbon and water relations were measured. There were differences in drought responses and recovery between species, but not as a function of evergreen or deciduous groups. exhibited the most rapid drought response, which was associated with a suite of physiological and morphological traits (larger plant size, the lowest hydraulic capacitance ( ), higher minimum conductance ( ) and lower (Huber value)). Upon re-watering, xylem water potential exhibited fast recovery in 1-3 days among species, while photosynthesis at saturating light ( ) and stomatal conductance ( ) recovery lagged behind water potential recovery depending on species, with recovery being more delayed than in most species. Furthermore, none of the six species exhibited significant hydraulic recovery during the 7 days re-watering period, indicating that xylem refilling was apparently limited; in addition, NSC availability had a minimal role in facilitating hydraulic recovery during this short-term period. Collectively, if water supply is limited by insignificant hydraulic recovery post-drought, the observed carbon assimilation recovery of seedlings may not be sustained over the longer term, potentially altering seedling regeneration and shifting forest species composition in subtropical China under climate change.
由于未来气候条件下降雨多变，亚热带树种可能会经历严重的干旱胁迫。然而，干旱后恢复水力功能的能力在具有不同叶习性（如常绿和落叶）的共生树种之间可能存在差异，并对未来森林组成产生影响。此外，水力恢复与与水碳有效性相关的生理和形态特征之间的联系仍未得到很好的理解。在这里，六种树种（四种常绿树种和两种落叶树种）的盆栽幼苗在防雨棚下户外种植。它们在有利的水分条件下生长，直到通过实验使其遭受土壤水分亏缺，导致水力传导率损失50%，然后将土壤重新浇水至田间持水量。测量了与碳和水关系相关的特征。不同树种在干旱响应和恢复方面存在差异，但不是常绿或落叶组的函数。表现出最快的干旱响应，这与一系列生理和形态特征有关（植株较大、最低水力电容、较高的最小导度和较低的（休伯值））。重新浇水后，木质部水势在1-3天内迅速恢复，而饱和光强下的光合作用和气孔导度的恢复根据树种落后于水势恢复，在大多数树种中，的恢复比更延迟。此外，在7天的重新浇水期内，六种树种均未表现出显著的水力恢复，这表明木质部再填充显然有限；此外，在这个短期期间，非结构性碳水化合物的可用性在促进水力恢复方面作用最小。总体而言，如果干旱后水力恢复微不足道导致供水受限，那么观察到的幼苗碳同化恢复可能无法长期维持，这可能会改变中国亚热带地区的幼苗更新并在气候变化下改变森林物种组成。
