文献类型：期刊文献

英文题名：Drought-Affected Populus simonii Carr. Show Lower Growth and Long-Term Increases in Intrinsic Water-Use Efficiency Prior to Tree Mortality

作者：Sun, Shoujia[1,2] Qiu, Lanfen[3] He, Chunxia[1,2] Li, Chunyou[4] Zhang, Jinsong[1,2] Meng, Ping[1,2]

第一作者：孙守家;Sun, Shoujia

通信作者：Meng, P[1];Meng, P[2]

机构：[1]Chinese Acad Forestry, Res Inst Forestry, Key Lab Tree Breeding & Cultivat State Forestry A, Beijing 100091, Peoples R China;[2]Nanjing Forestry Univ, Collaborat Innovat Ctr Sustainable Forestry South, Nanjing 210037, Jiangsu, Peoples R China;[3]Beijing Inst Landscape Architecture, Beijing Key Lab Ecol Funct Assessment & Regulat T, Beijing 100102, Peoples R China;[4]Agr Univ Hebei Baoding, Coll Landscape & Travel, Baoding 071000, Peoples R China

年份：2018

卷号：9

期号：9

外文期刊名：FORESTS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000448398100060)】；

基金：This research was funded by the National Natural Science Foundation of China (grant number: 31470705), the Special Fund for Forest Scientific Research in the Public Welfare (grant number: 201404206) and the Project of Co-Innovation Center for Sustainable Forestry in Southern China of Nanjing Forestry University.

语种：英文

外文关键词：Populus simonii Carr. (poplar); intrinsic water-use efficiency; tree rings; basal area increment; long-term drought

摘要：The Three-North Shelter Forest (TNSF) is a critical ecological barrier against sandstorms in northern China, but has shown extensive decline and death in Populus simonii Carr. in the last decade. We investigated the characteristics-tree-ring width, basal area increment (BAI), carbon isotope signature (delta C-13(cor)), and intrinsic water-use efficiency (iWUE)-of now-dead, dieback, and non-dieback trees in TNSF shelterbelts of Zhangbei County. Results from the three groups were compared to understand the long-term process of preceding drought-induced death and to identify potential early-warning proxies of drought-triggered damage. The diameter at breast height (DBH) was found to decrease with the severity of dieback, showing an inverse relationship. In all three groups, both tree-ring width and BAI showed quadratic relationships with age, and peaks earlier in the now-dead and dieback groups than in the non-dieback group. The tree-ring width and BAI became significantly lower in the now-dead and dieback groups than in the non-dieback group from 17 to 26 years before death, thus, these parameters can serve as early-warning signals for future drought-induced death. The now-dead and dieback groups had significantly higher delta C-13(cor) and iWUEs than the non-dieback group at 7-16 years prior to the mortality, indicating a more conservative water-use strategy under drought stress compared with non-dieback trees, possibly at the cost of canopy defoliation and long-term shoot dieback. The iWUE became significantly higher in the now-dead group than in the dieback group at 0-7 years before death, about 10 years later than the divergence of BAI. After the iWUE became significantly different among the groups, the now-dead trees showed lower growth and died over the next few years. This indicates that, for the TNSF shelterbelts studied, an abrupt iWUE increase can be used as a warning signal for acceleration of impending drought-induced tree death. In general, we found that long-term drought decreased growth and increased iWUE of poplar tree. Successive droughts could drive dieback and now-dead trees to their physiological limits of drought tolerance, potentially leading to decline and mortality episodes.