Abstract
Xylem embolism resistance has been identified as a key trait with a causal relation to drought-induced tree mortality, but not much is known about its intra-specific trait variability (ITV) in dependence on environmental variation. We measured xylem safety and efficiency in 300 European beech (Fagus sylvatica L.) trees across 30 sites in Central Europe, covering a precipitation reduction from 886 to 522 mm year−1. A broad range of variables that might affect embolism resistance in mature trees, including climatic and soil water availability, competition, and branch age, were examined. The average P50 value varied by up to 1 MPa between sites. Neither climatic aridity nor structural variables had a significant influence on P50. However, P50 was less negative for trees with a higher soil water storage capacity, and positively related to branch age, while specific conductivity (Ks) was not significantly associated with either of these variables. The greatest part of the ITV for xylem safety and efficiency was attributed to random variability within populations. We conclude that the influence of site water availability on P50 and Ks is low in European beech, and that the high degree of within-population variability for P50, partly due to variation in branch age, hampers the identification of a clear environmental signal.
Highlights
Drought-induced tree mortality has been documented worldwide (Allen et al 2010, 2015; Hartmann et al 2018), including European temperate forests (Braun et al 2020; SchuldtCommunicated by Kate McCulloh.Christoph Leuschner and Bernhard Schuldt shared senior authorship.In Central Europe, European beech (Fagus sylvatica L.) is the dominant species of natural forest vegetation and occurs under widely different precipitation regimes (Leuschner and Ellenberg 2017)
The fixed effects only explained 13% of the total variance in P50, we observed a significant influence of the plant-available water storage capacity (AWC) of the soil, i.e., soil physical properties that determine soil water availability in rainless periods and the flow resistance experienced by water-absorbing roots in drying soil
This study provides the largest intraspecific dataset on the xylem safety and efficiency of a tree species across a climatic gradient available so far
Summary
Drought-induced tree mortality has been documented worldwide (Allen et al 2010, 2015; Hartmann et al 2018), including European temperate forests (Braun et al 2020; SchuldtCommunicated by Kate McCulloh.Christoph Leuschner and Bernhard Schuldt shared senior authorship.In Central Europe, European beech (Fagus sylvatica L.) is the dominant species of natural forest vegetation and occurs under widely different precipitation regimes (Leuschner and Ellenberg 2017). Oecologia (2022) 198:629–644 been reported from locations at the range edge (e.g., Lakatos and Molnár 2009) and from the centre of its distribution range (Braun et al 2020; Leuschner 2020; Schuldt et al 2020) This matches earlier findings from physiological studies on the species’ drought sensitivity showing low water potentials, reduced nitrogen uptake, and a high water use efficiency under dry conditions (Rennenberg et al 2004; Geßler et al 2006) and dendroecological evidence of longterm growth declines in various Central European beech forest regions (review in Leuschner 2020). It remains questionable whether the intra-specific variability in plant hydraulic traits observed across marginal populations (Stojnic et al 2018) is likewise present in the centre of the species’ distribution range
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