Floristic Change at the Drought Limit of European Beech (Fagus sylvatica L.) to Downy Oak (Quercus pubescens) Forest in the Temperate Climate of Central Europe

Albert REIF,Fotios XYSTRAKIS,Uwe SAYER,Stefanie GÄRTNER

doi:10.15835/nbha45210971

Abstract

An increase in drought could cause shifts in species composition and vegetation structure. In forests it limits the occurrence of drought sensitive tree species which become replaced by drought tolerant tree species and forest communities. Under temperate macroclimatic conditions, European beech (Fagus sylvatica L.) naturally dominates the forested landscape, except on extremely shallow soil in combination with high irradiation. On these sites beech reaches its drought limit, and is replaced by forests dominated by species like downy Oak (Quercus pubescens s.l.) and English Oak (Quercus petraea L). Phytosociological and ecological data were collected in the transition (ecotone) between European beach stands and stands of more drought tolerant species in order to quantify the drought intensity threshold, above which beech is replaced by drought tolerant species. It was shown that favourable topographic and soil conditions partially compensated the unsuitable climatic conditions for beech. The ecotone between these forest types was found to be characterized by shallow soils with an available soil water storage capacity of 73 l/m² or less, and an irradiation intensity of 6000 MJ/m2 or more during the growing season. This indicates that under conditions of climate change beech would naturally still remain the dominant tree species on the majority of central European forest sites.

Highlights

European beech (Fagus sylvatica L.) would naturally dominate central European temperate forests because of its high physiological shade tolerance and competitiveness (Ellenberg and Leuschner, 2010)
European beech (Fagus sylvatica L.) naturally dominates the forested landscape, except on extremely shallow soil in combination with high irradiation. On these sites beech reaches its drought limit, and is replaced by forests dominated by species like downy oak (Quercus pubescens s.l.) and English oak (Quercus petraea L)
This study focuses on the tree species composition change at the drought limit of beech in southwestern Germany and the Canton of Schaffhausen in Switzerland by studying stands at the ecotone between forests with downy oak (Quercus pubescens Willd.) including its hybrids with English oak (Quercus petraea (Matt.) Liebl.) and beech (Fig. 1) (Kätzel et al, 2014)

Summary

Introduction

European beech (Fagus sylvatica L.) would naturally dominate central European temperate forests because of its high physiological shade tolerance and competitiveness (Ellenberg and Leuschner, 2010). Beech is restricted to shady slopes and/or deep soils and/or higher elevations (Ozenda et al, 1988; Peters, 1997; Reif and Löblich-Ille, 1999) In these locations, topography and soil compensate for the increasing macroclimatic drought, allowing for a “relatively constant” (Rubio and Sanchez-Palomares, 2006) water supply that favours beech. Topography and soil compensate for the increasing macroclimatic drought, allowing for a “relatively constant” (Rubio and Sanchez-Palomares, 2006) water supply that favours beech This example demonstrates that there are various environmental factors influencing the distribution of plant species and plant communities with a scale dependent relative importance (Thuiller et al, 2003) or, in other words, according to the “rule of relative site

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