Linear and non-linear responses of vegetation and soils to glacial-interglacial climate change in a Mediterranean refuge

Jens Holtvoeth,Bernd Wagner,Verushka Valsecchi,Stefan Schouten,George A Wolff,Hendrik Vogel,Katja Lindhorst

doi:10.1038/s41598-017-08101-y

Abstract

The impact of past global climate change on local terrestrial ecosystems and their vegetation and soil organic matter (OM) pools is often non-linear and poorly constrained. To address this, we investigated the response of a temperate habitat influenced by global climate change in a key glacial refuge, Lake Ohrid (Albania, Macedonia). We applied independent geochemical and palynological proxies to a sedimentary archive from the lake over the penultimate glacial-interglacial transition (MIS 6–5) and the following interglacial (MIS 5e-c), targeting lake surface temperature as an indicator of regional climatic development and the supply of pollen and biomarkers from the vegetation and soil OM pools to determine local habitat response. Climate fluctuations strongly influenced the ecosystem, however, lake level controls the extent of terrace surfaces between the shoreline and mountain slopes and hence local vegetation, soil development and OM export to the lake sediments. There were two phases of transgressional soil erosion from terrace surfaces during lake-level rise in the MIS 6–5 transition that led to habitat loss for the locally dominant pine vegetation as the terraces drowned. Our observations confirm that catchment morphology plays a key role in providing refuges with low groundwater depth and stable soils during variable climate.

Highlights

Lake sediment records are important environmental archives that record the response of terrestrial habitats to global climate change[1, 2]
Sedimentological[11] and archaeological findings[23] such as the remains of Neolithic pile dwellings behind the modern shoreline in the modern town of Ohrid certainly suggest that lake level was higher than present earlier in the Holocene, shaping the floodplains above modern lake level (Fig. 1B,C) and this may well have been the case during marine isotope stage (MIS) 5
We demonstrate how it is possible to disentangle the interplay between global climate change, vegetation and soil stock dynamics and how these were influenced by local factors, lake level and morphology

Summary

Introduction

Lake sediment records are important environmental archives that record the response of terrestrial habitats to global climate change[1, 2]. Lakes may not necessarily respond in a coherent manner within a region; global and regional trends can be overwhelmed by local aspects of environmental response such as changes in lake level, nutrient fluxes or soil stability[7]. In this context, the dynamics of the quantitatively important soil carbon pool within lacustrine catchments often remain elusive, due to the heterogeneous nature of the soil cover and its dependence on local geology and morphology[8,9,10]. Distributions of alkyl lipids together with bulk[28] and compound-specific isotope data (see Fig. S2 and Supplementary Materials) suggest that soil OM dominates the lake sediments, with little contribution from phytoplankton or macrophytes

Methods

Results

Conclusion