热带亚热带喀斯特森林木本植物的水力脆弱性分割  

Hydraulic vulnerability segmentation in woody plant species from tropical and subtropical karst forests

作　　者：余俊瑞 万春燕 朱师丹[1] YU Jun-Rui;WAN Chun-Yan;ZHU Shi-Dan(State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources,College of Forestry,Guangxi University,Nanning 530004,China)

机构地区：[1]广西大学林学院,亚热带农业生物资源保护与利用国家重点实验室,南宁530004

出　　处：《植物生态学报》2023年第11期1576-1584,共9页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(32060330)。

摘　　要：脆弱性分割是树木抗旱生理机制之一,但是关于喀斯特干旱生境植物的脆弱性分割情况及其生理意义尚不明确。该研究以热带、亚热带喀斯特森林共57种典型木本植物为研究材料,测定叶、茎脆弱性曲线以及最低水势,计算叶和茎的脆弱性分割(P50_(leaf-stem);数值越大代表脆弱性分割越强)以及水力安全边界,比较不同类群P50_(leaf-stem)的差异并分析其与水力安全边界的相关关系。结果表明:(1)该研究木本植物的P50_(leaf-stem)范围为-1.28-4.63 MPa,平均值为1.32 MPa,其中49种植物的P50_(leaf-stem)为正值(正向脆弱性分割);(2)灌木的P50_(leaf-stem)显著大于乔木,喀斯特山脊植物的P50_(leaf-stem)显著大于山谷植物,但是常绿和落叶植物之间的P50_(leaf-stem)差异不显著;(3)在旱季时期,P50_(leaf-stem)越大的植物,其叶水力安全边界越小,茎水力安全边界越大,说明叶片发生栓塞有助于降低茎干木质部的水力风险。该研究证实脆弱性分割是大部分热带亚热带喀斯特木本植物应对干旱胁迫的重要水力机制。Aims Vulnerability segmentation is one of physiological mechanisms underlying drought resistance for tree species.The aim of this study is to clarify the patterns of vulnerability segmentation and its physiological significance for woody species from drought-prone tropical and subtropical karst forests.Methods A total of 57 typical woody species were selected from tropical and subtropical karst forests.We measured their leaf and stem vulnerability curves and minimum water potential to calculate vulnerability segmentation(P50_(leaf-stem) is the difference in cavitation resistance between leaf and stem,with larger values indicating stronger vulnerability segmentation)and hydraulic safety margin.We compared the differences in P50_(leaf-stem) between different plant taxa and explored the relationships between P50_(leaf-stem) and hydraulic safety margin.Important findings(1)The P50_(leaf-stem) across the woody species ranged from–1.28 MPa to 4.63 MPa,with an average value of 1.32 MPa.Out of the 57 species,49 species showed a positive P50_(leaf-stem).(2)Shrub species showed higher P50_(leaf-stem) than tree species,and species from karst ridge showed higher P50_(leaf-stem) than those from karst valley.However,there was no significant difference in P50_(leaf-stem) between evergreen and deciduous species.(3)During the drought period,species with higher P50_(leaf-stem) tended to have smaller leaf hydraulic safety margin but larger stem hydraulic safety margin,indicating that occurrence of cavitation in leaves can reduce hydraulic risks of stems.This study confirms that vulnerability segmentation is an important hydraulic strategy for most tropical and subtropical karst woody species to deal with drought stress.

关 键 词：栓塞 干旱适应 水力安全边界 最低水势 植物类群 

分 类 号：S718.3[农业科学—林学]