Winter matters: Sensitivity to winter climate and cold events increases towards the cold distribution margin of European beech (Fagus sylvatica L.)

Abstract

Aim:The dominant forest tree in Europe, European beech (Fagus sylvatica L.), covers large areas of continental Europe and thus experiences diverse climatic conditions. In the face of predicted climate change and shifts of distribution ranges, it is important to understand the diverse climate-growth relationships towards distribution margins. Beech is generally reported to be sensitive to summer drought towards dry and continental regions; yet, few studies have investigated climate sensitivity towards the cold distribution margin of beech. We hypothesized that at colder sites (a) growth of beech is more sensitive to winter cold, (b) growth is less influenced by summer drought, and (c) stand-wide growth reductions (negative pointer years) are related to extreme winter cold events.Taxon: European beech (Fagus sylvatica L.). Location:A large gradient of decreasing winter temperature (ΔT >4 K along 500 km) from Rostock (Germany) to Gdańsk (Poland). Methods:We analysed climate-growth relationships and the nature of growth reductions of 11 beech stands from more central to cold marginal beech populations.Results: Towards the cold marginal populations, growth became increasingly sensitive to winter cold (February temperature) and less sensitive to summer water availability (June precipitation). Likewise, negative pointer years coincided with winter cold anomalies at the colder sites and with summer drought anomalies at the warmer sites. Thus, over the studied gradient, the general sensitivity of beech to summer drought transitions into sensitivity to winter cold. Main conclusions:A range shift of beech across the current cold distribution margin is often assumed to compensate for habitat and productivity losses of droughtprone southern and central populations. With respect to the winter cold sensitivity found in our study, such assumptions should be taken with caution. Since winter cold events are predicted to persist with similar frequency and magnitude even during predicted climate warming, beech populations in the newly colonized habitat might be significantly sensitive to winter cold.

Tree growth influenced by warming winter climate and summer moisture availability in northern temperate forests

“…Pederson et al (2004) postulated that in anomalously cold years with more frequent or severe embolism occurrence, resources that could be used for early growth would instead be used for recovery. A recent study by Weigel et al (2018) reports a relationship of beech growth reductions and winter cold that was enhanced towards cold-marginal populations. Furthermore, Weigel (2019) conducted a winter manipulation experiment in beech forests in northern Germany and Poland that shows winter cold, through sublethal root damage or reduced root nutrient uptake, affects beech growth negatively, a finding that is also supported by results presented in Reinmann, Susser, Demaria, and Templer (2019).…”

“…Network sites cover different portions of the distribution range of each species (Figure 1). We relied on chronologies that were previously developed for dendroclimatological (Cedro, 2004;Cedro & Cedro, 2018;Helama, Sohar, Läänelaid, Bijak, & Jaagus, 2018;Jansons, Matisons, Šēnhofa, Katrevičs, & Jansons, 2016;Läänelaid, Sohar, & Meikar, 2008;Matisons, Elferts, & Brūmelis, 2013;Sohar, Vitas, & Läänelaid, 2012;Vitas, 2004Vitas, , 2006Vitas, , 2011 and dendroecological analyses (Scharnweber et al, 2011;Scharnweber, Manthey, & Wilmking, 2013;van der Maaten, Mehl, Wilmking, & van der Maaten-Theunissen, 2017;van der Maaten-Theunissen et al, 2016;Vitas & Zunde, 2019;Weigel et al, 2018), as well as chronologies from the International Tree-Ring Database (ITRDB; n = 42 sites) and chronologies not previously published (n = 42 sites; Table S1).…”

“…Tree‐ring networks can be used to characterize the spatial and temporal patterns in the relationship between tree growth and climate and improve our ability to model the impacts of future climate (Charney et al, ; Klesse, DeRose, et al, ), especially for temperate, complex forests that provide diverse ecosystem services. Given the uncertainty of future climate, an improved understanding of the influence of climate on tree growth in temperate forest ecosystems is needed, especially for winter forest ecology, which has received comparatively less research attention (Weigel et al, ).…”

“…Given the uncertainty of future climate, an improved understanding of the influence of climate on tree growth in temperate forest ecosystems is needed, especially for winter forest ecology, which has received comparatively less research attention (Weigel et al, 2018).…”

A Framework for Determining Population-Level Vulnerability to Climate: Evidence for Growth Hysteresis in Chamaecyparis thyoides Along Its Contiguous Latitudinal Distribution

“…While the central populations appear vulnerable to summer warming, winter warming might also increase growth such that it could offset some of this potential negative impact on growth. Warm winter temperatures have been found to be associated with increased growth in the Northern Hemisphere for decades (e.g., Brubaker, 1980;Graumlich, 1993;Pederson et al, 2004;Babst et al, 2013;Martin-Benito et al, 2018;Weigel et al, 2018;Alexander et al, 2019;LeBlanc et al, accepted). Mechanisms that explain how dormant season temperatures might influence growth in conifers are, however, not an area of consensus.…”