Simulating functional diversity of European natural forests along climatic gradients

Kirsten Thonicke*, Maik Billing, Werner von Bloh, Boris Sakschewski, Ülo Niinemets, Josep Peñuelas, J. Hans C. Cornelissen, Yusuke Onoda, Peter van Bodegom, Michael E. Schaepman, Fabian D. Schneider, Ariane Walz

*Corresponding author for this work

    Research output: Contribution to JournalArticleAcademicpeer-review

    Abstract

    Aim: We analyse how functional diversity (FD) varies across European natural forests to understand the effects of environmental and competitive filtering on plant trait distribution. Location: Forest ecosystems in Europe from 11°W to 36°E and 29.5°N to 62°N. Taxon: Pinaceae, Fagaceae and Betulaceae, Oleaceae, Tiliaceae, Aceraceae, Leguminosae (unspecific). Methods: We adopted the existing Dynamic Global Vegetation Model Lund-Potsdam-Jena managed Land of flexible individual traits (LPJmL-FIT) for Europe by eliminating both bioclimatic limits of plant functional types (PFTs) and replacing prescribed values of functional traits for PFTs with emergent values under influence of environmental filtering and competition. We quantified functional richness (FR), functional divergence (FDv) and functional evenness (FE) in representative selected sites and at Pan-European scale resulting from simulated functional and structural trait combinations of individual trees. While FR quantifies the amount of occupied trait space, FDv and FE describe the distribution and abundance of trait combinations, respectively, in a multidimensional trait space. Results: Lund-Potsdam-Jena managed Land of flexible individual traits reproduces spatial PFTs and local trait distributions and agrees well with observed productivity, biomass and tree height of European natural forests. The observed site-specific trait distributions and spatial gradients of traits of the leaf- and stem-resource economics spectra coincide with environmental filtering and the competition for light and water in environments with strong abiotic stress. Where deciduous and needle-leaved trees co-occur, for example, in boreal and mountainous forests, the potential niche space is wide (high FR), and extreme ends in the niche space are occupied (high FDv). We find high FDv in Mediterranean forests where drought increasingly limits tree growth, thus niche differentiation becomes more important. FDv decreases in temperate forests where a cold climate increasingly limits growth efficiency of broad-leaved summer green trees, thus reducing the importance of competitive exclusion. Highest FE was simulated in wet Atlantic and southern Europe which indicated relatively even niche occupation and thus high resource-use efficiency. Main Conclusions: We find FD resulting from both environmental and competitive filtering. Pan-European FR, FDv and FE demonstrate the influence of climate gradients and intra- and inter-PFT competition. The indices underline a generally high FD of natural forests in Europe. Co-existence of functionally diverse trees across PFTs emerges from alternative (life-history) strategies, disturbance and tree demography.

    Original languageEnglish
    Pages (from-to)1069-1085
    Number of pages17
    JournalJournal of Biogeography
    Volume47
    Issue number5
    Early online date17 Feb 2020
    DOIs
    Publication statusPublished - May 2020

    Funding

    The authors thank three anonymous reviewers for their careful and constructive comments that greatly improved the manuscript. This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No 641762 (ECOPOTENTIAL). The study has been supported by the TRY initiative on plant traits (http://www.try-db.org). The TRY initiative and database is hosted, developed and maintained by J. Kattge and G. Boenisch (MaxPlanck Institute for Biogeochemistry, Jena, Germany) in collaboration with the German Centre for Integrative Biodiversity Research (iDiv). We thank Giovanni Gligora for contributing his data to TRY. TRY is been supported by DIVERSITAS core project bioDISCOVERY, the IGBP, the Global Land Project, the UK Natural Environment Research Council (NERC) through its program QUEST (Quantifying and Understanding the Earth System) and the French programmes 'Climat, Environnement, Societe' and 'Fondation pour la Recherche sur la Biodiversite'. The contribution of M. E. Schaepman is supported by the University of Zurich Research Priority Program on Global Change and Biodiversity (URPP GCB). The research carried out at the Jet Propulsion Laboratory, California Institute of Technology, was under a contract with the National Aeronautics and Space Administration. Government sponsorship is acknowledged.

    FundersFunder number
    DIVERSITAS
    German Centre for Integrative Biodiversity Research
    IGBP
    MaxPlanck Institute for Biogeochemistry
    National Aeronautics and Space Administration
    Horizon 2020 Framework Programme
    Natural Environment Research Council
    Fondation pour la Recherche sur la Biodiversite
    Universität Zürich
    Horizon 2020641762
    iDiv

      Keywords

      • boreal forest
      • co-existence
      • competitive filtering
      • dynamic global vegetation model
      • environmental filtering
      • flexible individual traits
      • mediterranean forest
      • natural forest
      • temperate forest

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