Abstract
Background: Acclimation to light is a driver of tropical forest dynamics and key to understanding the coexistence of dipterocarps, and how their demographic rates and traits trade-off.
Aims: We examined light niche divergence in six dipterocarp species and hypothesised that seedlings can be functionally grouped, and allocate resources to either growth or storage in response to light changes.
Methods: A pot experiment was performed to measure size-specific growth rate, wood density and total non-structural carbohydrate (NSC) concentrations of dipterocarp seedlings exposed to a simulated gap opening.
Results: Light-demanding species responded to a gap opening with increased growth and decreased wood density, whereas shade-tolerant species showed a greater relative increase in NSC concentration. Iditol – an alditol – was identified, and Dryobalanops lanceolata responded to a gap opening with a significantly smaller increase in alditol concentration compared to other species.
Conclusions: We group light-demanding and shade-tolerant species based on their acclimation to light and show that a generalist species is unique based on its response of NSC concentration to a gap opening. Our findings emphasise that the ecology of these species needs to be further studied in the context of their physiology to support their effective use in large-scale forest restoration efforts.
Acknowledgements
We thank: Charles Godfray and Glen Reynolds for their help in setting up and supporting the Sabah Biodiversity Experiment; Karin Beer, Peter Huonker, Jannine Brunner, Yann Hautier, Dzaeman Dzulkifli, Martin Stenflo, Bo Burla, Maik Hadorn, René Huesi and staff from the Malua Field Station for field and laboratory assistance; Francis Q. Brearley, C.E. Timothy Paine, Michael O’Brien, Toby Marthews, Manuell Koller, Martin Mächler, Fränzi Körner, Stefanie von Felten, Douglas Bates, Marc Cadotte and Jakob Weiner for comments and statistical help related to seedling growth estimation; Aurélie Egert and Samuel C. Zeeman for support and comments on the analysis of starch and soluble sugars; Urs Stalder for comments and help on the identification of iditol and five anonymous reviewers for helpful comments on the manuscript. This is paper no. 13 of the Sabah Biodiversity Experiment. The Economic Planning Unit, Malaysia and the Danum Valley Management Committee approved this field study.
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Notes on contributors
Philippe Saner
Philippe Saner is an environmental scientist with a main interest in tropical plant community ecology and the restoration of tropical forests.
Christopher D. Philipson
Christopher D. Philipson is a quantitative ecologist interested by the diversity of natural ecosystems and understanding the processes that maintain diversity.
Shaun Peters
Shaun Peters is a lecturer with a research interest within the broad purvey of plant water-soluble carbohydrate metabolism.
Felix Keller
Felix Keller is a professor emeritus with a research interest in water-soluble carbohydrates in plants.
Laurent Bigler
Laurent Bigler is head of the mass spectrometry lab with a strong interest in the identification of new compounds associated with plant metabolism.
Lindsay A. Turnbull
Lindsay A. Turnbull is an associate professor with a research interest in how and why plant species are so different to each other, and what the consequences of these differences may be for ecosystems.
Andy Hector
Andy Hector is a community ecologist interested in biodiversity loss and its consequences for the stability and functioning of ecosystems and the provision of ecological services.