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Abstract Organisms of all species must balance their allocation to growth, survival and recruitment. Among tree species, evolution has resulted in different life‐history strategies for partitioning resources to these key demographic processes. Life‐history strategies in tropical forests have often been shown to align along a trade‐off between fast growth and high survival, that is, the well‐known fast–slow continuum. In addition, an orthogonal trade‐off has been proposed between tall stature—resulting from fast growth and high survival—and recruitment success, that is, a stature−recruitment trade‐off. However, it is not clear whether these two independent dimensions of life‐history variation structure tropical forests worldwide.We used data from 13 large‐scale and long‐term tropical forest monitoring plots in three continents to explore the principal trade‐offs in annual growth, survival and recruitment as well as tree stature. These forests included relatively undisturbed forests as well as typhoon‐disturbed forests. Life‐history variation in 12 forests was structured by two orthogonal trade‐offs, the growth−survival trade‐off and the stature−recruitment trade‐off. Pairwise Procrustes analysis revealed a high similarity of demographic relationships among forests. The small deviations were related to differences between African and Asian plots.Synthesis. The fast–slow continuum and tree stature are two independent dimensions structuring many, but not all tropical tree communities. Our discovery of the consistency of demographic trade‐offs and life‐history strategies across different forest types from three continents substantially improves our ability to predict tropical forest dynamics worldwide.
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Small disturbances and subsequent competition for light can maintain a diversity of demographic strategies in a neotropical forest: Results from model–data integration
Abstract Niche differentiation with respect to light availability as it varies across succession has often been thought to explain tree species coexistence. Demographic light‐related niches represented by growth‐survival and stature‐recruitment trade‐offs and captured by demographic groups (slow, fast, long‐lived pioneers, short‐lived breeders and intermediate) have been shown to accurately represent the biomass dynamics of secondary and old‐growth forests in central Panama in a model. However, whether the simple mechanisms of that well‐parameterized and accurate model are enough to support the long‐term coexistence of demographic groups across these trade‐offs has yet to be tested.Here, we develop a model to test whether stochastic, small‐scale gap disturbances and subsequent competition for light can support the long‐term coexistence of the observed demographic groups in the Barro Colorado Island forest dynamics plot. Specifically, to test whether the demographic differences among species promote coexistence, we compare niche simulation models, parameterized by the different demographic groups, to a variety of neutral models, where the species have the same demographic parameters.Upon exploring the estimated range of possible parameterizations of recruitment (a difficult‐to‐measure parameter), we identify several parameterizations where differences among groups along the growth‐survival and stature‐recruitment trade‐off axes facilitate long‐term coexistence. We find that gap disturbances are essential for these results, indicating that it is the differences in the subsequent competition for light through time that provide the opportunity for stabilizing niche differentiation. Additionally, the parameterizations that generate stable coexistence display successional negative density dependence and realistic within‐patch post‐disturbance forest dynamics.Synthesis. This model‐data integration exercise indicates that small‐scale disturbances and subsequent competition for light may be significant forces for stable diversity maintenance of demographic groups along the growth–survival and stature–recruitment trade‐off axes in a neotropical forest. This result, however, holds only for a subset of the empirically reasonable recruitment parameters, indicating the importance of improving the understanding of recruitment and its demographic trade‐offs for understanding demographic strategy coexistence.
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- Award ID(s):
- 1939559
- PAR ID:
- 10617491
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Ecology
- Volume:
- 113
- Issue:
- 9
- ISSN:
- 0022-0477
- Format(s):
- Medium: X Size: p. 2625-2638
- Size(s):
- p. 2625-2638
- Sponsoring Org:
- National Science Foundation
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