Towards a better ecological understanding of metacommunity stability: A multiscale framework to disentangle population variability and synchrony effects

Abstract

1. Despite great progress in our understanding of the mechanisms governing ecosystem stability in local communities, we still lack knowledge at a larger spatial scale. Studying the stability of metacommunities requires assessing the temporal stability and synchrony of populations across space and organizational levels.Previous attempts to disentangle these effects have provided limited ecological interpretations, and conceptual improvements are needed to identify the underlying ecological processes.2. We propose an extended framework aiming at disentangling simultaneously the relative effects of population stability and different types of synchronies on metacommunity stability. We adapted previous methods of decomposing stability into a new set of indices associated with clearer ecological hypotheses.Particularly, we provide synchrony indices that are not affected by statistical properties of the metacommunity but focus on species responses to environment, demography and interactions. We applied this framework to a unique dataset describing the sorted biomass of individual plant populations, across 12 communities of a species-rich meadow, and for 16 years. The communities were sampled in different treatments of fertilization and dominant removal to evaluate the effect of environmental heterogeneity on stability.3. We found higher stability at a larger spatial scale, mainly due to statistical averaging (portfolio effect). The variability of individual populations was an important determinant of the stability of the whole metacommunity. Consistent with the hypothesis of a common response to environmental conditions, we found that the fluctuations of populations were mostly synchronized (within and between species) at a large spatial scale and tended to destabilize the metacommunity.On the other hand, opposite fluctuations (anti-synchrony) between populations occurred at the local scale, probably due to local species interactions. Synthesis.Our framework appears as a powerful tool to test how ecological processes occurring simultaneously at different spatial and organizational scales affect the stability of metacommunities. This study advances our | 1633Journal of Ecology SEGRESTIN aNd LEPŠ c Depending on local conditions (e.g. soil type, elevation), weather fluctuations can be favourable or unfavourable for plant growth. For example, a warm year can be beneficial for growth or create drought conditions that repress growth depending on the soil field capacity for water and access to groundwater. d Favourable conditions (e.g. warm, and wet years) should enhance growth while unfavourable conditions (e.g. cold, and dry years) should repress growth for all species. e Trait dissimilarity between species results in (1) different responses to environmental fluctuations due to differences in resource access (e.g. deep rooting allows drought resistance during dry years) or (2) same responses to environmental fluctuations but with different timing (after a disturbance, fast-growing species can recover faster than slow-growing...

A unified framework for partitioning the drivers of stability of ecological communities

“…However, this section aims at demonstrating the use of our framework rather than giving new ecological conclusions. Indeed, data from this experiment have been already reported in previous work (see Lepš et al., 2018; Májeková et al., 2014; Segrestin & Lepš, 2022).…”

“…All analyses conducted in this study rely on this package. The data used for the case study have already been published and is freely accessible in the Dryad Digital Repository: https://doi.org/10.5061/dryad.8gtht76r9 (Segrestin & Lepš, 2022).…”

Why are plant communities stable? Disentangling the role of dominance, asynchrony and averaging effect following realistic species loss scenario

“…Colours correspond with Figure 3. stochastic variability and the stabilization of the whole population (Segrestin & Lepš, 2022).…”

“…Furthermore, we controlled for unexpected variability in space using statistical blocks as random effects. We therefore focus on biotic drivers such as competition, which has been shown to be theoretically and empirically dependent on diversity (Lepš et al, 2018;Segrestin & Lepš, 2022;Thibaut & Connolly, 2013). Disturbance intensity can also strongly influence community stability (e.g.…”