Climate Signals for Growth Variations of F. sylvatica, P. abies, and P. sylvestris in Southeast Germany over the Past 50 Years

Annette Debel,Wolfgang Jens-Henrik Meier,Achim Bräuning

doi:10.3390/f12111433

Annette Debel, Wolfgang Jens-Henrik Meier + Show 1 more

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https://doi.org/10.3390/f12111433

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Journal: Forests	Publication Date: Oct 21, 2021
Citations: 15	License type: CC BY 4.0

Affiliation: University of Erlangen-Nuremberg

Abstract

Since recent drought events have already caused severe damage to trees and droughts in the near future are expected to occur even more frequently, this study investigated the response of forest ecosystems to changing climate conditions in the topographically complex region of Bavaria, southeast Germany. For this purpose, climate–growth relationships of important European deciduous and coniferous tree species were investigated over the past 50 years at three middle mountain ranges and corresponding basins. A response analysis between tree-ring width and climate variables was applied to detect modifications in tree responses comparing two 25-year periods at individual forest sites. Furthermore, tree responses to climatic extreme years and seasons were analyzed using a superposed epoch analysis. The results showed that Scots pine (Pinus sylvestris) proved to be the most vulnerable and least drought-resistant of all investigated tree species. Likewise, Norway spruce (Picea abies) and European beech (Fagus sylvatica) revealed a higher drought sensitivity over the past 25 years, even though an extended growing season partially improved tree growth at high-elevation sites. In conclusion, all studied tree species were affected by drought events, even at humid high-elevation sites. Correlations with daily climate variables confirmed that even short-term weather conditions could strongly influence trees’ radial growth. Tree responses to climate conditions have shifted significantly between past and present periods but vary considerably among sites and are generally stronger in humid regions than in already dry areas.

Highlights

Accepted: 19 October 2021According to climate models, temperatures and summer drought stress will increase in southern Germany within the 21st century [1], but climate change is already perceptible: summer months have already become hotter and drier [2]
[38,39,40,41,42], precipitation during the the growing was correlated with tree growth at the two high elevation sites within boreal bioclimatic zone (HC and HE) (Figures 2 and 3) [20]
Increased mean temperatures in subperiod II (Figure 8) [27] caused a shift in environmental conditions at humid mountainous sites as well (Figure 9a)

Summary

Introduction

Accepted: 19 October 2021According to climate models, temperatures and summer drought stress will increase in southern Germany within the 21st century [1], but climate change is already perceptible: summer months have already become hotter and drier [2]. 2019 was listed as an exceptionally hot summer [5]. As water availability is the primary growth-limiting factor for most European tree species [6], current reports on the state of forests in Central Europe are alarming [5]. Scientists and foresters detected a decreasing vitality of European tree species and a rising incidence of tree mortality [4,5]. Since forest ecosystems are complex and influenced by numerous factors besides climate, the combination of environmental factors leading to tree mortality is not yet fully understood [7,8]. Climate sensitivity differs between tree species, and the level of resilience is species-specific [6,7,9,10]. Picea abies, which has been preferred in forestry and frequently planted outside of its natural distribution range, appears to be most vulnerable to future warming and drier climate conditions [11,12,13,14,15,16]

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