Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City 04510, Mexico.
Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia.
Tree Physiol. 2024 Oct 3;44(10). doi: 10.1093/treephys/tpae121.
Predicting how plants respond to drought requires an understanding of how physiological mechanisms and drought response strategies occur, as these strategies underlie rates of gas exchange and productivity. We assessed the response of 11 plant traits to repeated experimental droughts in four co-occurring species of central Australia. The main goals of this study were to: (i) compare the response to drought between species; (ii) evaluate whether plants acclimated to repeated drought; and (iii) examine the degree of recovery in leaf gas exchange after cessation of drought. Our four species of study were two tree species and two shrub species, which field studies have shown to occupy different ecohydrological niches. The two tree species (Eucalyptus camaldulensis Dehnh. and Corymbia opaca (D.J.Carr & S.G.M.Carr) K.D.Hill & L.A.S.Johnson) had large reductions in stomatal conductance (gs) values, declining by 90% in the second drought. By contrast, the shrub species (Acacia aptaneura Maslin & J.E.Reid and Hakea macrocarpa A.Cunn. ex R.Br.) had smaller reductions gs in the second drought of 52 and 65%, respectively. Only A. aptaneura showed a physiological acclimatation to drought due to small declines in gs versus ᴪpd (0.08 slope) during repeated droughts, meaning they maintained higher rates of gs compared with plants that only experienced one final drought (0.19 slope). All species in all treatments rapidly recovered leaf gas exchange and leaf mass per area following drought, displaying physiological plasticity to drought exposure. This research refines our understanding of plant physiological responses to recurrent water stress, which has implications for modelling of vegetation, carbon assimilation and water use in semi-arid environments under drought.
预测植物对干旱的响应需要了解生理机制和干旱响应策略的发生方式，因为这些策略是气体交换和生产力速率的基础。我们评估了在澳大利亚中部四种共存物种中，11 种植物性状对反复实验性干旱的响应。本研究的主要目的是：（i）比较物种间对干旱的响应；（ii）评估植物是否对反复干旱产生了适应；（iii）研究在停止干旱后叶片气体交换的恢复程度。我们研究的四个物种是两种乔木和两种灌木，野外研究表明它们占据了不同的生态水学生态位。两种乔木物种（Eucalyptus camaldulensis Dehnh. 和 Corymbia opaca (D.J.Carr & S.G.M.Carr) K.D.Hill & L.A.S.Johnson）的气孔导度（gs）值大幅下降，第二次干旱时下降了 90%。相比之下，灌木物种（Acacia aptaneura Maslin & J.E.Reid 和 Hakea macrocarpa A.Cunn. ex R.Br.）的 gs 在第二次干旱中分别下降了 52%和 65%。只有 A. aptaneura 表现出对干旱的生理适应，因为在反复干旱期间 gs 与 ᴪpd（0.08 斜率）的下降幅度较小，这意味着与仅经历一次最终干旱的植物相比，它们维持了更高的 gs 速率（0.19 斜率）。所有物种在所有处理中，在经历干旱后，叶片气体交换和叶片比叶面积迅速恢复，表现出对干旱暴露的生理可塑性。这项研究深化了我们对植物对反复水胁迫的生理响应的理解，这对在干旱条件下模拟半干旱环境中的植被、碳同化和水分利用具有重要意义。
