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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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Stabilising role of seed banks and the maintenance of bacterial diversity
Abstract Coexisting species often exhibit negative frequency dependence due to mechanisms that promote population growth and persistence when rare. These stabilising mechanisms can maintain diversity through interspecific niche differences, but also through life‐history strategies like dormancy that buffer populations in fluctuating environments. However, there are few tests demonstrating how seed banks contribute to long‐term community dynamics and the maintenance of diversity. Using a multi‐year, high‐frequency time series of bacterial community data from a north temperate lake, we documented patterns consistent with stabilising coexistence. Bacterial taxa exhibited differential responses to seasonal environmental conditions, while seed bank dynamics helped maintain diversity over less‐favourable winter periods. Strong negative frequency dependence in rare, but metabolically active, taxa suggested a role for biotic interactions in promoting coexistence. Together, our results provide field‐based evidence that niche differences and seed banks contribute to recurring community dynamics and the long‐term maintenance of diversity in nature.
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- Award ID(s):
- 1934554
- PAR ID:
- 10374414
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Ecology Letters
- Volume:
- 24
- Issue:
- 11
- ISSN:
- 1461-023X
- Page Range / eLocation ID:
- p. 2328-2338
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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