Drought-Affected Populus simonii Carr. Show Lower Growth and Long-Term Increases in Intrinsic Water-Use Efficiency Prior to Tree Mortality
| Autor: | Lanfen Qiu, Ping Meng, Chunxia He, Chunyou Li, Shou-Jia Sun, Jinsong Zhang |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
0106 biological sciences
Canopy intrinsic water-use efficiency 010504 meteorology & atmospheric sciences Drought tolerance Diameter at breast height Forestry lcsh:QK900-989 Biology Windbreak 01 natural sciences Basal area Horticulture tree rings Shoot Populus simonii Carr. (poplar) basal area increment long-term drought lcsh:Plant ecology Populus simonii Water-use efficiency 010606 plant biology & botany 0105 earth and related environmental sciences |
| Zdroj: | Forests Volume 9 Issue 9 Forests, Vol 9, Iss 9, p 564 (2018) |
| ISSN: | 1999-4907 |
| DOI: | 10.3390/f9090564 |
| Popis: | 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&mdash tree-ring width, basal area increment (BAI), carbon isotope signature (13Ccor), and intrinsic water-use efficiency (iWUE)&mdash 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 13Ccor and iWUEs than the non-dieback group at 7&ndash 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&ndash 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. |
| Databáze: | OpenAIRE |
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