Water uptake depth is coordinated with leaf water potential, water-use efficiency and drought vulnerability in karst vegetation
Water uptake depth is coordinated with leaf water potential, water-use efficiency and drought vulnerability in karst vegetation
复制标题
喀斯特植被吸水深度与叶片水势、水分利用效率和干旱脆弱性相协调
DOI：
10.1111/nph.16971
复制
发表时间：
2020-11-04
期刊：
影响因子：
9.4
通讯作者：
Querejeta, Jose, I
中科院分区：
文献类型：
--
作者：
Ding, Yali;Nie, Yunpeng;Querejeta, Jose, I
根部获得基岩水储存或地下水是使植物在季节性干旱环境中存活的一个重要特征。然而，干旱植物群落的水分吸收深度、叶水平水分利用效率(WUEI)和水势之间的协调程度还没有得到很好的了解。在一个具有稀薄骨架土壤的亚热带喀斯特生态系统中，我们进行了135d的降雨排斥试验，以评估11种生活型和叶片习性不同的共生木本植物在湿润生长季节对严重干旱的响应。干旱期间木质部水分同位素组成的显著差异揭示了物种之间明显的生态水文生态位分离。共存物种的叶水势在干旱期间的不同行为在很大程度上是由于根获得更深的、暂时稳定的水源的差异。直径较小、吸水率较低、负水势较大和WUEI较低的树种表现出广泛的干旱引起的冠层脱落和/或死亡。相反，直径较大、吸水率较高、叶片水平WUEI较高、等水行为较多的物种在干旱中存活，只有适度的冠层落叶。严重的水分限制施加了强大的环境过滤和/或选择压力，导致了树木直径、吸水深度、等/各向异性行为、WUEI和干旱脆弱性之间的紧密协调。
Root access to bedrock water storage or groundwater is an important trait allowing plant survival in seasonally dry environments. However, the degree of coordination between water uptake depth, leaf-level water-use efficiency (WUEi) and water potential in drought-prone plant communities is not well understood.We conducted a 135-d rainfall exclusion experiment in a subtropical karst ecosystem with thin skeletal soils to evaluate the responses of 11 co-occurring woody species of contrasting life forms and leaf habits to a severe drought during the wet growing season.Marked differences in xylem water isotopic composition during drought revealed distinct ecohydrological niche separation among species. The contrasting behaviour of leaf water potential in coexisting species during drought was largely explained by differences in root access to deeper, temporally stable water sources. Smaller-diameter species with shallower water uptake, more negative water potentials and lower WUEi showed extensive drought-induced canopy defoliation and/or mortality. By contrast, larger-diameter species with deeper water uptake, higher leaf-level WUEi and more isohydric behaviour survived drought with only moderate canopy defoliation.Severe water limitation imposes strong environmental filtering and/or selective pressures resulting in tight coordination between tree diameter, water uptake depth, iso/anisohydric behaviour, WUEi and drought vulnerability in karst plant communities.