Disentangling competitive vs. climatic drivers of tropical forest mortality

Michiel Pillet, Emilie Joetzjer, Camille Belmin, Jérôme Chave, Philippe Ciais, Aurélie Dourdain, Margaret Evans, Bruno Hérault, Sebastiaan Luyssaert, Benjamin Poulter*

*Corresponding author for this work

    Research output: Contribution to JournalArticleAcademicpeer-review


    Tropical forest mortality is controlled by both biotic and abiotic processes, but how these processes interact to determine forest structure is not well understood. Using long-term demography data from permanent forest plots at the Paracou Tropical Forest Research Station in French Guiana, we analysed the relative influence of competition and climate on tree mortality. We found that self-thinning is evident at the stand level, and is associated with clumped mortality at smaller scales (<2 m) and regular spacing of living trees at intermediate (2.5-7.5 m) scales. A competition index (CI) based on spatial clustering of dead trees was used to build predictive mortality models, which also accounted for climate interactions. The model that most closely fitted observations included both the CI and climatic variables, with climate-only and competition-only models less informative than the full model. There was strong evidence for U-shaped size-specific mortality, with highest mortality for small and very large trees, as well as sensitivity of trees to drought, especially when temperatures were high, and when soils were water saturated. The effect of the CI was more complex than expected a priori: a higher CI was associated with lower mortality odds, which we hypothesize is caused by gap-phase dynamics, but there was also evidence for competition-induced mortality at very high CI values. The strong signature of competition as a control over mortality at the stand and individual scales confirms its important role in determining tropical forest structure. The complexity of the competition-mortality relationship and its interaction with climate indicates that a thorough consideration of the scale of analysis is needed when inferring the role of competition in tropical forests, but demonstrates that climate-only mortality models can be significantly improved by including competition effects, even when ignoring species-specific effects. Synthesis. Empirical models such as the one developed here can help constrain and improve process-based vegetation models, serving both as a benchmark and as a means to disentangle mortality processes. Tropical vegetation dynamic models would benefit greatly from explicitly considering the role of competition in stand development and self-thinning while modelling demography, as well as its interaction with climate.

    Original languageEnglish
    Pages (from-to)1165-1179
    Number of pages15
    JournalJournal of Ecology
    Issue number3
    Early online dateNov 2017
    Publication statusPublished - May 2018


    Baisie, Mi. Baisie, K. Ficadici, A. Etienne, F. Kwasie, K. Martinus, P. Naisso and R. Sante. The Paracou station is currently funded by the Region Guyane (Observatoire du Carbone), in the framework of the PO Feder (projet GFclim), and was partially funded by an Investissement d’Avenir grant of the ANR (CEBA: ANR-10-LABEX-0025). P.C. acknowledges support from the European Research Council Synergy grant ERC-2013-SyG-610028 IMBALANCE-P. M.P. thanks Nichole Casebeer for providing feedback on the manuscript’s figures and writing. M.P. was supported by the National Science Foundation graduate research fellowship grant DGE-1143953. European Union Climate, Grant/Award Number: EIT/CLIMATE KIC/SGA2016/1; CIRAD; Region Guyane (Observatoire du Carbone); Investissement d’Avenir, Grant/ Award Number: ANR-10-LABEX-0025; European Research Council Synergy, Grant/ Award Number: ERC-2013-SyG-610028; National Science Foundation, Grant/Award Number: DGE-1143953 Funding was provided by the European Union Climate KIC grant FOREST, specific grant agreement no. EIT/CLIMATE KIC/SGA2016/1, and by CIRAD, the institution responsible for Paracou Tropical Forest Research Station (http://paracou.cirad.fr). This study was made possible thanks to the important field work realized at Paracou by many people of CIRAD: L. Schmitt, P. Petronelli, D.Max, O. N’Gwete, Mo.

    FundersFunder number
    European Union ClimateANR-10-LABEX-0025, EIT/CLIMATE KIC/SGA2016/1
    European Union Climate KIC
    National Science FoundationDGE-1143953
    Seventh Framework Programme610028
    European Research Council


      • Climate change
      • Competition
      • DGVM
      • Demography
      • Gap dynamics
      • Mortality
      • Paracou
      • Ripley
      • Self-thinning
      • Tropical forest
      • Turnover


      Dive into the research topics of 'Disentangling competitive vs. climatic drivers of tropical forest mortality'. Together they form a unique fingerprint.

      Cite this