Taxonomic and functional turnover are decoupled in European peat bogs

Bjorn J M Robroek,Albert Bleeker,Richard J Payne,Jos T A Verhoeven,Katarzyna Zając,Magalí Martí,Vincent E J Jassey,Nancy B Dise,Luca Bragazza,Jasper Van Ruijven,Alexandre Buttler,Jens Kattge,Simon J M Caporn,Bo H Svensson

doi:10.1038/s41467-017-01350-5

Abstract

In peatland ecosystems, plant communities mediate a globally significant carbon store. The effects of global environmental change on plant assemblages are expected to be a factor in determining how ecosystem functions such as carbon uptake will respond. Using vegetation data from 56 Sphagnum-dominated peat bogs across Europe, we show that in these ecosystems plant species aggregate into two major clusters that are each defined by shared response to environmental conditions. Across environmental gradients, we find significant taxonomic turnover in both clusters. However, functional identity and functional redundancy of the community as a whole remain unchanged. This strongly suggests that in peat bogs, species turnover across environmental gradients is restricted to functionally similar species. Our results demonstrate that plant taxonomic and functional turnover are decoupled, which may allow these peat bogs to maintain ecosystem functioning when subject to future environmental change.

Highlights

Summary of generalised linear models testing the relationships between functional redundancy of vascular plants and bryophytes, and bioclimatic variables: MAT mean annual temperature, TS seasonality in temperature, MAP mean annual precipitations, SOx sulphate, and NHx nitrogen atmospheric depositions
Our analysis demonstrates the highly dynamic response of European peat bog plant species composition to changes in environmental conditions, with temperature and precipitation being the most important drivers, followed by atmospheric N and S deposition
Despite relatively high taxonomic turnover, community level functional redundancy was maintained along the environmental gradients by opposing cluster-specific effects. Together these results suggest that taxonomic and functional turnover of peat bog plant communities along environmental gradients are decoupled

Summary

Hypnales

We present an analysis of the relationships between plant species composition, functional trait composition, and a number of major environmental drivers, such as temperature, precipitation and atmospheric deposition, using data on plant species composition from 56 ombrotrophic Sphagnum-dominated peat bogs across Europe (Fig. 1). We provide evidence for general patterns in species turnover (i.e., change in species composition, or species replacement) along environmental gradients: peat bog plant species are divided into two clusters with convergent within–cluster, but divergent between–cluster responses along the main environmental gradients. We conclude that non-random species replacement of functionally identical species between both networks conserves functional redundancy at the ecosystem level, which may sustain the robustness of peat bog ecosystems to anthropogenic drivers of environmental change

Results

Discussion

Methods