The role of conspecific density dependence (CDD) in the maintenance of species richness is a central focus of tropical forest ecology. However, tests of CDD often ignore the integrated effects of CDD over multiple life stages and their long-term impacts on population demography. We combined a 10-year time series of seed production, seedling recruitment and sapling and tree demography of three dominant Southeast Asian tree species that adopt a mast-fruiting phenology. We used these data to construct individual-based models that examine the effects of CDD on population growth rates ( λ) across life-history stages. Recruitment was driven by positive CDD for all species, supporting the predator satiation hypothesis, while negative CDD affected seedling and sapling growth of two species, significantly reducing λ. This negative CDD on juvenile growth overshadowed the positive CDD of recruitment, suggesting the cumulative effects of CDD during seedling and sapling development has greater importance than the positive CDD during infrequent masting events. Overall, CDD varied among positive, neutral and negative effects across life-history stages for all species, suggesting that assessments of CDD on transitions between just two stages (e.g. seeds seedlings or juveniles mature trees) probably misrepresent the importance of CDD on population growth and stability.
|Number of pages||9|
|Journal||Proceedings of the Royal Society of London. B, Biological Sciences|
|Early online date||15 Jun 2022|
|Publication status||Published - 29 Jun 2022|
Bibliographical noteFunding. M.J.O. was supported by the Atracción de Talento Investiga-dor Fellowship from the Comunidad de Madrid (grant no. 2018-T1/AMB-11095). The collection of some fecundity and recruitment data was supported by grants from the British Ecological Society and NERC (grant nos. NER/A/S/2001/00835, NE/D003822/1 and NE/T006560/1) to D.F.R.P.B. cknowledgements. We would like to thank Udin for his work starting this experiment and maintaining it over the years. We appreciate the significant advice from Dr Will Petry on the modelling of the masting system. This manuscript contributes to the University Research Priority Program on Global Change and Biodiversity. The Danum Valley Forest GEO plot is a core project of the Southeast Asia Rain Forest Research Partnership (SEARRP). We thank SEARRP partners, especially Yayasan Sabah for their support, and HSBC Malaysia and the University of Zurich for funding. We are grateful to the research assistants who are conducting the census, in particular the team leader Alex Karolus, and to Mike Bernados and Bill McDonald for species identifications. We thank Shameema Esufali for advice and training. We acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing resources that contributed this work (http://www.msi.umn.edu). This publication is number 24 from the research team associated with the SBE at the Malua Field Station
- Tropical Climate