秦岭9个树种的木质部栓塞特性与水力安全风险  

Xylem embolism characteristics and hydraulic safety risks of nine tree species in Qinling Mountains

作　　者：陈思佚 唐燕[2] 何腾 江永康 杜光源[1] CHEN Si-Yi;TANG Yan;HE Teng;JIANG Yong-Kang;DU Guang-Yuan(College of Science,Northwest A&F University,Yangling,Shaanxi 712100,China;College of Life Sciences,Northwest A&F University,Yangling,Shaanxi 712100,China)

机构地区：[1]西北农林科技大学理学院,陕西杨凌712100 [2]西北农林科技大学生命科学学院,陕西杨凌712100

出　　处：《植物生态学报》2024年第9期1213-1222,共10页Chinese Journal of Plant Ecology

基　　金：西北农林科技大学数理基础学科交叉研究专项(2452022378)资助

摘　　要：近年来,气候变化引起秦岭森林树木死亡率升高和脆弱性加剧,对秦岭的生物多样性和生态功能产生不利影响。该研究以秦岭森林的9个典型树种:红桦(Betula albosinensis)、刺榛(Corylus ferox)、青榨槭(Acer davidii)、五尖槭(Acer maximowiczii)、麻栎(Quercus acutissima)、槲栎(Quercus aliena)、华山松(Pinus armandii)、云杉(Picea asperata)和华北落叶松(Larix principis-rupprechtii)为研究对象,解析各树种木质部栓塞特性,评估水力安全风险,揭示秦岭森林退化的植物水力学机制,为秦岭生态保护提供科学依据。该研究采用Cochard离心机法和Sperry离心机法测量不同水势下枝条的比导水率损失百分比(PLC),建立木质部栓塞脆弱性曲线(VCs);采用低压液流计法测定最大木质部比导水率(K_(max));采用压力室法原位测定正午木质部水势(P_(md)),在此基础上解析各树种的水力安全边际(HSM),评估水力失效风险。结果表明:在9个树种中,针叶树种华山松、云杉、华北落叶松和阔叶树种青榨槭具有“s”形栓塞脆弱性曲线,而阔叶树种红桦、刺榛、麻栎、槲栎和五尖槭则为“r”形栓塞脆弱性曲线;其PLC为50%时的木质部水势(P50)的大小关系为:云杉<华北落叶松<华山松<青榨槭<五尖槭<红桦<槲栎<刺榛<麻栎;HSM的大小关系为:麻栎<刺榛<红桦<华北落叶松<槲栎<五尖槭<青榨槭<华山松<云杉,其中,红桦、刺榛和麻栎的HSM接近0,具有极高的水力失效风险。总体来看,阔叶树种比针叶树种具有更高的水分运输效率,但是其抗栓塞能力较差,面临着更大的水力失效风险。Aims Climate warming exacerbate vulnerability of forest ecosystem in the Qinling Mountains,leading to increased forest mortality,and declined ecological function.The objectives of this study were to investigate xylem embolism vulnerability and hydraulic safety margin of nine tree species in the Qinling Mountains.Methods In this study,nine tree species of the Qinling Mountains,Betula albosinensis,Corylus ferox,Acer davidii,Acer maximowiczii,Quercus acutissima,Quercus aliena,Pinus armandii,Picea asperata and Larix principis-rupprechtii in two different forest sites,Xunyangba village in mid altitude and Pingheliang ridge in high altitude,were studied.Cochard centrifugation and Sperry centrifugation methods were used to establish vulnerability curves(VCs),which was defined as the percentage loss of hydraulic conductivity(PLC)vs.xylem water potential.The xylem maximum hydraulic conductivity(K_(max)of branches was measured by low pressure flowmeter.The midday xylem water potential(P_(md)was determined by the pressure chamber,which was used to obtain the hydraulic safety margin(HSM)to assess the risk of hydraulic failure for each tree species in natural conditions.Important findings 1)Xylem embolism vulnerability of nine species was ranked as Picea asperata<Larix principis-rupprechtii<Pinus armandii<Acer davidii<Acer maximowiczii<Betula albosinensis<Quercus aliena<Corylus ferox<Quercus acutissima.The HSM was ranked as Picea asperata>Pinus armandii>Acer davidii>Acer maximowiczii>Quercus aliena>Larix principis-rupprechtii>Betula albosinensis>Corylus ferox>Quercus acutissima.2)The six broadleaf species in the Qinling Mountains had less negative 50%PLC water potential(P50)and narrower HSM in average than the three conifer species,and therefore were under greater risk of hydraulic failure.3)The HSM of B.albosinensis,C.ferox and Q.acutissima were close to 0,which indicated an extremely high risk of xylem embolism.In conclusion,broadleaf species in Qinling Mountains had higher water transport efficiency than conifer species,in

关 键 词：栓塞脆弱性 脆弱性曲线 水力安全边际 比导水率 水力失效风险 

分 类 号：S718.5[农业科学—林学]