Vegetation dynamics of beech forests on limestone in central Germany over half a century – effects of climate change, forest management, eutrophication or game browsing?

Steffi Heinrichs,Wulfard Winterhoff,Wolfgang Schmidt

doi:10.7809/b-e.00059

Abstract

The aim of this study was to investigate the vegetation dynamics of suboceanic, submontane, mesic beech forests on limestone that are very rich in spring geophytes over half a century, considering changes in abiotic and biotic conditions including global climate change. Vegetation releves sampled in the Gottinger Wald, southern Lower Saxony, Germany, between 1955 and 1960 (n = 25) and in 1968 (n = 10) were re-surveyed in 2009 on quasi-permanent plots. Differences in species composition, species abundance and vegetation structure were compared between inventories using detrended correspondence analysis (DCA), multiple response permutation procedure (MRPP) and the Wilcoxon signed ranks test. Forty to fifty years ago, a shrub layer was scarcely present, but is common today as a consequence of intensified hunting. An increasing abundance of Allium ursinum, Urtica dioica and Sambucus nigra and a general shift to species composition with higher Ellenberg indicator values for nitrogen can be ascribed to atmospheric nitrogen deposition. The spring geophytes A. ursinum, Corydalis cava and Leucojum vernum can also benefit from global climate change with an earlier start of the vegetation period. A shift towards more oceanic conditions, with mild winters in the past fifty years, may also have increased the competitive strength of evergreen species that are susceptible to long frost periods (e.g. Hedera helix). The resampling of the beech forest vegetation on limestone revealed that many factors have influenced the dynamics over the past half century. These include eutrophication and a reduction in roe deer browsing, but our results also indicate a possible influence of climate change on community composition. In focussing on a small dataset from a very rich sub-unit of beech forests on limestone, the positive response of the spring geophytes becomes particularly obvious.

Highlights

For centuries European forests have been affected by humans, either directly through forest management or, since industrialisation and the intensification of agriculture, indirectly by eutrophication and acid deposition (e.g. FalkengrenGrerup 1986, Bernhardt 2005)
Though climatic change was present throughout the history of forests (e.g. “the Little Ice Age”; Bradshaw & Zackrisson 1990, Huntley 1990, Campbell & McAndrews 1993), in recent years the global climate warming has emerged as a important factor influencing forest ecosystems, with frequently occuring extreme events that lower forest stability (Overpeck et al 1990, Wohlgemuth et al 2008)
The potential influence of global warming on forest vegetation has so far been mainly investigated by analysing species composition along temperature gradients (e.g. Van der Veken et al 2004)

Summary

Introduction

For centuries European forests have been affected by humans, either directly through forest management or, since industrialisation and the intensification of agriculture, indirectly by eutrophication and acid deposition (e.g. FalkengrenGrerup 1986, Bernhardt 2005). Actual climate-induced vegetation changes have been observed across Europe in terms of an earlier phenology (Dierschke 2000, Fitter & Fitter 2002, Menzel et al 2006, Sparks et al 2009) or species shifts to higher elevations or latitudes (Root et al 2003, Lesica & McCune 2004, Walther et al 2005a, 2005b, 2007, Pauli et al 2007, Lenoir et al 2008, Walther 2010). Records of abundance changes at fine scales in different European forest regions as a result of climate change are scarce (but see Økland et al 2004 and Lenoir et al 2010) and mainly restricted to an observed spread of some evergreen species (Carraro et al 2001, Dierschke 2005, Hilker et al 2005, Diekmann 2010) and the early spring-species Allium ursinum

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