Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China.
Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China.
Physiol Plant. 2019 Dec;167(4):645-660. doi: 10.1111/ppl.12922. Epub 2019 Apr 16.
Plant responses to drought and their subsequent rehydration can provide evidence for forest dynamics within the context of climate change. In this study, the seedlings of two native species (Vitex negundo var. heterophylla, Quercus acutissima) and two exotic species (Robinia pseudoacacia, Amorpha fruticosa) to China were selected in a greenhouse experiment. The gas exchange, stem hydraulic parameters, plant osmoprotectant contents and antioxidant activities of the seedlings that were subjected to sustained drought and rehydration (test group) as well as those of well-irrigated seedlings (control group) were measured. The two native species exhibited a greater degree of isohydry with drought because they limited the stomatal opening timely from the onset of the drought. However, the two exotic species showed a more 'water spender'-like strategy with R. pseudoacacia showing anisohydric responses and A. fruticosa showing isohydrodynamic responses to drought. Severe drought significantly decreased the leaf gas exchange rates and hydraulic properties, whereas the instantaneous water use efficiency and osmoprotectant contents increased markedly. Most of the physiological parameters recovered rapidly after mild drought rehydration, but the water potential and/or supply of nonstructural carbohydrates did not recover after severe drought rehydration. The results demonstrate that the xylem hydraulic conductivity and shoot water potential jointly play a crucial role in the drought recovery of woody plants. In brief, the native species may play a dominant role in the future in warm-temperate forests because they employ a better balance between carbon gain and water loss than the alien species under extreme drought conditions.
植物对干旱的响应及其随后的复水可为气候变化背景下的森林动态提供证据。本研究在温室实验中选择了两种本地物种（Vitex negundo var. heterophylla，Quercus acutissima）和两种外来物种（Robinia pseudoacacia， Amorpha fruticosa）的幼苗。对持续干旱和复水（实验组）以及充分灌溉的幼苗（对照组）的幼苗的气体交换、茎水力参数、植物渗透调节物质含量和抗氧化活性进行了测量。两种本地物种表现出更强的耐旱性，因为它们在干旱开始时及时限制了气孔的开放。然而，两种外来物种表现出更类似于“水耗者”的策略，其中 R. pseudoacacia 表现出非等水响应，A. fruticosa 表现出等水力动力学响应对干旱的响应。严重干旱显著降低了叶片气体交换率和水力特性，而瞬时水分利用效率和渗透调节物质含量显著增加。轻度干旱复水后，大多数生理参数迅速恢复，但严重干旱复水后水势和/或非结构性碳水化合物的供应并未恢复。结果表明，木质部水力传导率和冠层水势共同在木本植物的干旱恢复中起着关键作用。简而言之，在极端干旱条件下，与外来物种相比，本地物种可能在未来的暖温带森林中发挥主导作用，因为它们在碳增益和水分损失之间取得了更好的平衡。
