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| Titel |
Drought-influenced mortality of tree species with different predawn leaf water dynamics in a decade-long study of a central US forest |
| VerfasserIn |
L. Gu, S. G. Pallardy, K. P. Hosman, Y. Sun |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 10 ; Nr. 12, no. 10 (2015-05-18), S.2831-2845 |
| Datensatznummer |
250117933
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| Publikation (Nr.) |
 copernicus.org/bg-12-2831-2015.pdf |
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| Zusammenfassung |
| Using decade-long continuous observations of tree mortality and predawn leaf
water potential (ψpd) at the Missouri Ozark AmeriFlux (MOFLUX)
site, we studied how the mortality of important tree species varied and how
such variations may be predicted. Water stress determined inter-annual
variations in tree mortality with a time delay of 1 year or more, which was
correlated fairly tightly with a number of quantitative predictors formulated
based on ψpd and precipitation regimes. Predictors based on
temperature and vapor pressure deficit anomalies worked reasonably well,
particularly for moderate droughts. The exceptional drought of the year 2012
drastically increased the mortality of all species, including drought-tolerant oaks, in the subsequent year. The drought-influenced tree mortality
was related to the species position along the spectrum of ψpd
regulation capacity with those in either ends of the spectrum being
associated with elevated risk of death. Regardless of species and drought
intensity, the ψpd of all species recovered rapidly after
sufficiently intense rain events in all droughts. This result, together with
a lack of immediate leaf and branch desiccation, suggests an absence of
catastrophic hydraulic disconnection in the xylem and that tree death was
caused by significant but indirect effects. Species differences in the
capacity of regulating ψpd and its temporal integral were
magnified under moderate drought intensities but diminished towards wet and
dry extremes. Severe droughts may overwhelm the capacity of even drought-tolerant species to maintain differential levels of water potential as the
soil becomes exhausted of available water in the rooting zone, thus rendering
them more susceptible to death if predisposed by other factors such as age. |
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