Evidence of elevation-specific growth changes of spruce, fir, and beech in European mixed mountain forests during the last three centuries

Torben Hilmers,Gerhard Schütze,Hans Pretzsch,Mathieu Lévesque,Peter Biber,Thomas A Nagel,Zuzana Sitková ,Michal Bošeľa ,Miren Del Rı́o ,Andrej Bončina,Admir Avdagić,Branko Stajić,David I Forrester,Franz Binder,Tzvetan Zlatanov,Roberto Tognetti,Aida Ibrahimspahić,Enno Uhl,Dejan Stojanović,Laura Dobor

doi:10.1139/cjfr-2019-0368

Abstract

In Europe, mixed mountain forests, primarily comprised of Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.), and European beech (Fagus sylvatica L.), cover about 10 × 106 ha at elevations between ∼600 and 1600 m a.s.l. These forests provide invaluable ecosystem services. However, the growth of these forests and the competition among their main species are expected to be strongly affected by climate warming. In this study, we analyzed the growth development of spruce, fir, and beech in moist mixed mountain forests in Europe over the last 300 years. Based on tree-ring analyses on long-term observational plots, we found for all three species (i) a nondecelerating, linear diameter growth trend spanning more than 300 years; (ii) increased growth levels and trends, the latter being particularly pronounced for fir and beech; and (iii) an elevation-dependent change of fir and beech growth. Whereas in the past, the growth was highest at lower elevations, today’s growth is superior at higher elevations. This spatiotemporal pattern indicates significant changes in the growth and interspecific competition at the expense of spruce in mixed mountain forests. We discuss possible causes, consequences, and silvicultural implications of these distinct growth changes in mixed mountain forests.

Highlights

In temperate Europe, mixed mountain forests of Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.), and European beech (Fagus sylvatica L.) connect the lowland beech forest communities with the spruce-dominated alpine forest types
Silver fir, and European beech have coexisted for thousands of years in mixture without active management or with close-to-nature forestry across this region (Magin 1959; Preuhsler 1979)
Based on the aforementioned considerations about elevational-dependent climate change effects in mixed mountain forests, we developed the following questions

Summary

Introduction

In temperate Europe, mixed mountain forests of Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.), and European beech (Fagus sylvatica L.) connect the lowland beech forest communities with the spruce-dominated alpine forest types. Whereas forests in the lowlands were exploited much more intensively and were mostly converted to age-class systems by clear-cutting, forests located at higher elevations were often managed less intensively or were left in a more natural state compared with lowland forests (Magin 1959). We analyzed a species combination that covers an area of about 10 × 106 ha of mixed mountain forests in Europe (Hilmers et al 2019). Silver fir, and European beech have coexisted for thousands of years in mixture without active management or with close-to-nature forestry across this region (Magin 1959; Preuhsler 1979). We will be better able to manage the balanced and successful interaction among the three species

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Discussion

Conclusion