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Increased sensitivity to drought across successional stages in natural Norway spruce (Picea abies (L.) Karst.) forests of the Calimani Mountains, Romania

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Key message Winter drought becomes a limiting factor of forest stand growth by the end of the twentieth century. Abstract Disturbances strongly influence the structure of natural forests. The frequency and severity of natural disturbances, as well as drought events, are expected to increase with climate change. Our study investigated if forests with differing forest structures related to disturbance histories also differed in sensitivity to drought. In a natural forest landscape in the Calimani Mountains of the Eastern Carpathians, Romania, we used six forest patches to represent different successional stages, from early- to late-successional stages. We used two temporal resolutions of the Standardized Precipitation-Evapotranspiration Index to describe short and long water resource dynamics within or between hydrological years, respectively. We detected an increase in the importance of winter drought across all successional stages; it was first identified in the oldest patch in the 1970s, and it consecutively affected younger patches. We observed that different forest structures do not lead to substantial differences in trends in drought–growth relationships. A shift in sensitivity to water availability from early spring to winter occurred over the twentieth century. These findings suggest that the impact of climate change on Norway spruce forest ecosystems of the Eastern Carpathians will likely be difficult to mitigate at a local scale using traditional forestry practices.
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Vol.:(0123456789)
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Trees (2019) 33:1345–1359
https://doi.org/10.1007/s00468-019-01862-1
ORIGINAL ARTICLE
Increased sensitivity todrought acrosssuccessional stages innatural
Norway spruce (Picea abies (L.) Karst.) forests oftheCalimani
Mountains, Romania
K.Svobodová1,2 · T.Langbehn2· J.Björklund2· M.Rydval2· V.Trotsiuk2· R.C.Morrissey2· V.Čada2· P.Janda2·
K.Begovič2· J.Ágh‑Lábusová2· J.S.Schurman2· M.Nováková2· D.Kozák2· O.Kameniar2· M.Synek2· M.Mikoláš2·
M.Svoboda2
Received: 25 September 2018 / Accepted: 23 April 2019 / Published online: 6 May 2019
© Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract
Key message Winter drought becomes a limiting factor of forest stand growth by the end of the twentieth century.
Abstract Disturbances strongly influence the structure of natural forests. The frequency and severity of natural disturbances,
as well as drought events, are expected to increase with climate change. Our study investigated if forests with differing forest
structures related to disturbance histories also differed in sensitivity to drought. In a natural forest landscape in the Calimani
Mountains of the Eastern Carpathians, Romania, we used six forest patches to represent different successional stages, from
early- to late-successional stages. We used two temporal resolutions of the Standardized Precipitation-Evapotranspiration
Index to describe short and long water resource dynamics within or between hydrological years, respectively. We detected
an increase in the importance of winter drought across all successional stages; it was first identified in the oldest patch in the
1970s, and it consecutively affected younger patches. We observed that different forest structures do not lead to substantial
differences in trends in drought–growth relationships. A shift in sensitivity to water availability from early spring to winter
occurred over the twentieth century. These findings suggest that the impact of climate change on Norway spruce forest
ecosystems of the Eastern Carpathians will likely be difficult to mitigate at a local scale using traditional forestry practices.
Keywords Disturbance history· SPEI· Synchronized tree growth· Climate change· Carpathians
Introduction
Droughts are predicted to become more frequent and hotter
(IPCC 2013), and they may become lethal for many plants
under warming conditions (Allen etal. 2015) in European
temperate forests (Lindner etal. 2010). The considerable
influence of climate change on natural disturbance regimes
in forests has been recognized for the past two centuries
(Schelhaas etal. 2003). An increase in natural disturbance
frequency and severity is expected (Dale etal. 2001; Seidl
etal. 2017). To understand the possible consequences of
climate change on future forest growth, it is necessary to
characterize current and past drought–growth relationships.
Ongoing climate change has yielded increasing tempera-
tures and changes in precipitation regimes (IPCC 2013). In
a warmer world, intensification of the hydrologic cycle is
expected (Dore 2005). A simple climatic water balance can
be represented by the Standardized Precipitation-Evapotran-
spiration Index (SPEI; Vicente-Serrano etal. 2010), which
characterizes monthly differences between precipitation
and potential evapotranspiration. Different time resolutions
of SPEI can help us better understand and manage forest
growth–drought interactions (McKee etal. 1993), because
seasonal water deficits may not be restricted only to drier
Communicated by A. Geßler.
Electronic supplementary material The online version of this
article (https ://doi.org/10.1007/s0046 8-019-01862 -1) contains
supplementary material, which is available to authorized users.
* K. Svobodová
kristynaxsvobodova@gmail.com
1 Faculty ofEnvironmental Sciences, Czech University ofLife
Sciences Prague, Kamýcká 129, Suchdol, 16500Prague,
CzechRepublic
2 Faculty ofForestry andWood Sciences, Czech University
ofLife Sciences Prague, Kamýcká 129, Suchdol,
16500Prague, CzechRepublic
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... While assessments of changes in the climate sensitivity of trees in Europe are common (Castaldi et al., 2020;Kolář et al., 2017;Ponocná et al., 2016;Schurman et al., 2019;Svobodová et al., 2019), most studies rely on monthly climatic data. However, applying climate data with a monthly resolution induces an artificial barrier that lacks a physiological explanation. ...
... Climate-growth relationships of spruce have been extensively investigated across Europe (Begović et al., 2020;Bošel'a et al., 2014;Jevšenak et al., 2021;Schurman et al., 2019;Sidor et al., 2015;Svobodová et al., 2019;van der Maaten-Theunissen et al., 2013). This species was reported to be drought-limited, particularly at low elevations (Sidor et al., 2015;van der Maaten-Theunissen et al., 2013), which is further modulated by prevailing soil conditions (Rehschuh et al., 2017). ...
... similarly experienced a significant warming trend in recent decades (Micu et al., 2021). Continuous warming has changed sensitivity to climate across Europe for spruce (Bošel'a et al., 2014;Popa et al., 2024a;Schurman et al., 2019;Svobodová et al., 2019) and other tree species as well (Castaldi et al., 2020;Dobrovolný et al., 2016;Hofgaard et al., 2019;Unterholzner et al., 2024). ...
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