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Dispersal increases the resilience of tropical Savanna and forest distributions

Goel, N and Gutta, V and Levin, SA and Staver, AC (2020) Dispersal increases the resilience of tropical Savanna and forest distributions. In: American Naturalist, 195 (5). pp. 833-850.

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Official URL: https://dx.doi.org/10.1086/708270


Global change may induce changes in savanna and forest distributions, but the dynamics of these changes remain unclear. Classical biome theory suggests that climate is predictive of biome distributions, such that shifts will be continuous and reversible. This view, however, cannot explain the overlap in the climatic ranges of tropical biomes, which some argue may result from fire-vegetation feedbacks, maintaining savanna and forest as bistable states. Under this view, biome shifts are argued to be discontinuous and irreversible. Mean-field bistable models, however, are also limited, as they cannot reproduce the spatial aggregation of biomes. Here we suggest that both models ignore spatial processes, such as dispersal, which may be important when savanna and forest abut. We examine the contributions of dispersal to determining biome distributions using a 2Dreaction-diffusion model, comparing results qualitatively to empirical savanna and forest distributions in sub-SaharanAfrica.We find that the diffusion model resolves both the aforementioned limitations of biome models. First, local dispersive spatial interactions, with an underlying precipitation gradient, can reproduce the spatial aggregation of biomes with a stable savanna-forest boundary. Second, the boundary is determined not only by the amount of precipitation but also by the geometrical shape of the precipitation contours. These geometrical effects arise from continental-scale source-sink dynamics, which reproduce the mismatch between biome and climate. Dynamically, the spatial model predicts that dispersal may increase the resilience of tropical biome in response to global change: The boundary continuously tracks climate, recovering following disturbances, unless the remnant biome patches are too small.

Item Type: Journal Article
Publication: American Naturalist
Additional Information: The copyright of this article belongs to UNIV CHICAGO PRESS
Keywords: biome; dispersal; ecological modeling; global change; precipitation (climatology); savanna; tropical forest, Sub-Saharan Africa
Department/Centre: Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited: 23 Jun 2020 06:55
Last Modified: 23 Jun 2020 06:55
URI: http://eprints.iisc.ac.in/id/eprint/65488

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