Unraveling the relative role of light and water competition between lianas and trees in tropical forests: A vegetation model analysis

Félicien Meunier, Hans Verbeeck, Betsy Cowdery, Stefan A. Schnitzer, Chris M. Smith-Martin, Jennifer S. Powers, Xiangtao Xu, Martijn Slot, Hannes P.T. De Deurwaerder, Matteo Detto, Damien Bonal, Marcos Longo, Louis S. Santiago, Michael Dietze

Research output: Contribution to journalArticlepeer-review

Abstract

Despite their low contribution to forest carbon stocks, lianas (woody vines) play an important role in the carbon dynamics of tropical forests. As structural parasites, they hinder tree survival, growth and fecundity; hence, they negatively impact net ecosystem productivity and long-term carbon sequestration. Competition (for water and light) drives various forest processes and depends on the local abundance of resources over time. However, evaluating the relative role of resource availability on the interactions between lianas and trees from empirical observations is particularly challenging. Previous approaches have used labour-intensive and ecosystem-scale manipulation experiments, which are infeasible in most situations. We propose to circumvent this challenge by evaluating the uncertainty of water and light capture processes of a process-based vegetation model (ED2) including the liana growth form. We further developed the liana plant functional type in ED2 to mechanistically simulate water uptake and transport from roots to leaves, and start the model from prescribed initial conditions. We then used the PEcAn bioinformatics platform to constrain liana parameters and run uncertainty analyses. Baseline runs successfully reproduced ecosystem gas exchange fluxes (gross primary productivity and latent heat) and forest structural features (leaf area index, aboveground biomass) in two sites (Barro Colorado Island, Panama and Paracou, French Guiana) characterized by different rainfall regimes and levels of liana abundance. Model uncertainty analyses revealed that water limitation was the factor driving the competition between trees and lianas at the drier site (BCI), and during the relatively short dry season of the wetter site (Paracou). In young patches, light competition dominated in Paracou but alternated with water competition between the wet and the dry season on BCI according to the model simulations. The modelling workflow also identified key liana traits (photosynthetic quantum efficiency, stomatal regulation parameters, allometric relationships) and processes (water use, respiration, climbing) driving the model uncertainty. They should be considered as priorities for future data acquisition and model development to improve predictions of the carbon dynamics of liana-infested forests. Synthesis. Competition for water plays a larger role in the interaction between lianas and trees than previously hypothesized, as demonstrated by simulations from a process-based vegetation model.

Original languageEnglish (US)
Pages (from-to)519-540
Number of pages22
JournalJournal of Ecology
Volume109
Issue number1
DOIs
StatePublished - Jan 2021

Bibliographical note

Funding Information:
This research was funded by the European Research Council Starting Grant 637643 (TREECLIMBERS). All simulations were run using the computational resources provided by the Flemish Supercomputer Center, funded by Ghent University, FWO and the Flemish Government. During the preparation of this manuscript, F.M. was first funded by the BAEF and the WBI as a research fellow then by the FWO as a junior postdoctoral fellow and is thankful to these organizations for their financial support. We are grateful to the whole PEcAn group and the ED2 team for helpful discussions and support related to the functioning of BETY, PEcAn and ED2. The research carried out at the Jet Propulsion Laboratory, California Institute of Technology, was under a contract with the National Aeronautics and Space Administration. M.L. was supported by the NASA Postdoctoral Program, administered by Universities Space Research Association under contract with NASA. The flux tower on BCI was supported by Forest Global Earth Observatory of the Smithsonian Tropical Research Institute in Panama. M.D. was supported by the Carbon Mitigation Initiative at Princeton University. We warmly thank the Ecological Forecasting lab for proofreading early versions of this manuscript and the unconditional support. M. Dietze and PEcAn development were supported by NSF 1458021.

Funding Information:
This research was funded by the European Research Council Starting Grant 637643 (TREECLIMBERS). All simulations were run using the computational resources provided by the Flemish Supercomputer Center, funded by Ghent University, FWO and the Flemish Government. During the preparation of this manuscript, F.M. was first funded by the BAEF and the WBI as a research fellow then by the FWO as a junior postdoctoral fellow and is thankful to these organizations for their financial support. We are grateful to the whole PEcAn group and the ED2 team for helpful discussions and support related to the functioning of BETY, PEcAn and ED2. The research carried out at the Jet Propulsion Laboratory, California Institute of Technology, was under a contract with the National Aeronautics and Space Administration. M.L. was supported by the NASA Postdoctoral Program, administered by Universities Space Research Association under contract with NASA. The flux tower on BCI was supported by Forest Global Earth Observatory of the Smithsonian Tropical Research Institute in Panama. M.D. was supported by the Carbon Mitigation Initiative at Princeton University. We warmly thank the Ecological Forecasting lab for proofreading early versions of this manuscript and the unconditional support. M. Dietze and PEcAn development were supported by NSF 1458021.

Publisher Copyright:
© 2020 The Authors. Journal of Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society

Keywords

  • PEcAn
  • competition for resources
  • dynamic global vegetation model
  • ecosystem demography model
  • lianas
  • plant–plant interactions
  • uncertainty analysis

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