Spatial heterogeneity enhance robustness of large multi-species ecosystems

Abstract

Understanding ecosystem stability and functioning is a long-standing goal in theoretical ecology, with one of the main tools being dynamical modelling of species abundances. With the help of spatially unresolved (well-mixed) population models and equilibrium dynamics, limits to stability and regions of various ecosystem robustness have been extensively mapped in terms of diversity (number of species), types of interactions, interaction strengths, varying interaction networks (for example plant-pollinator, food-web) and varying structures of these networks. Although many insights have been gained, the impact of spatial extension is not included in this body of knowledge. Recent studies of spatially explicit modelling on the other hand have shown that stability limits can be crossed and diversity increased for systems with spatial heterogeneity in species interactions and/or chaotic dynamics. Here we show that such crossing and diversity increase can appear under less strict conditions. We find that the mere possibility of varying species abundances at different spatial locations make possible the preservation or increase in diversity across previous boundaries thought to mark catastrophic transitions. In addition, we introduce and make explicit a multitude of different dynamics a spatially extended complex system can use to stabilise. This expanded stabilising repertoire of dynamics is largest at intermediate levels of dispersal. Thus we find that spatially extended systems with intermediate dispersal are more robust, in general have higher diversity and can stabilise beyond previous stability boundaries, in contrast to well-mixed systems.

The topology of spatial networks affects stability in experimental metacommunities

“…The effects of weak interactions in communities can also be idiosyncratic. In general, it has been proposed that they have stabilizing properties for communities compared with strong interactions [19,[47][48][49]. Recent studies have shown that different trophic groups contribute differently to metacommunity stability.…”

“…Spatial dynamics can have stabilizing effects on metacommunities [18,19] and metaecosystems [20]. Although it has been shown that the pattern of habitat connectivity affects metacommunity persistence [21] and can modulate the importance of the different drivers of metacommunity dynamics [22,23], we currently lack a clear understanding of how it affects metacommunity stability.…”

Defining, estimating, and understanding the fundamental niches of complex animals in heterogeneous environments

“…Heterogeneous environments can be more favorable to a mobile and selective species than homogeneous ones (even ones that are “on average” marginally better). Even environments that are hostile on average can offer localized refugia and therefore encourage species viability (Pettersson & Nilsson Jacobi, 2021). The framework presented here can quantify exactly how buffered real animals are from hostile environments.…”