TY - JOUR
T1 - Dispersal increases the resilience of tropical Savanna and forest distributions
AU - Goel, Nikunj
AU - Gutta, Vishwesha
AU - Levin, Simon A.
AU - Staver, A. Carla
N1 - Funding Information:
Funding for this work was provided by a grant from the National Science Foundation to A.C.S. (DMS-1615531) and S.A.L. (DMS-1615585) and by Yale University. V.G. is supported by the DBT-IISc partnership program. We thank Thierry Emonet for help with technical problems simulating the integro-differential equationmodel.We also thank Stephen Stearns and members of the Staver lab, especially Julie Aleman, Joshua Daskin, and Madelon Case for manuscript feedback. We also thank the two anonymous reviewers for their constructive feedback.
Funding Information:
Funding for this work was provided by a grant from the National Science Foundation to A.C.S. (DMS-1615531) and S.A.L. (DMS 1615585) and by Yale University. V.G. is supported by the DBT-IISc partnership program. We thank Thierry Emonet for help with technical problems simulating the integro-differential equation model. We also thank Stephen Stearns and members of the Staver lab, especially Julie Aleman, Joshua Daskin, and Madelon Case for manuscript feedback. We also thank the two anonymous reviewers for their constructive feedback.
Publisher Copyright:
© 2020 by The University of Chicago.
PY - 2020/5/1
Y1 - 2020/5/1
N2 - 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.
AB - 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.
KW - Alternative stable states
KW - Climate change
KW - Dispersal
KW - Resilience
KW - Savanna-forest boundary
KW - Source-sink dynamics
UR - http://www.scopus.com/inward/record.url?scp=85084393199&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85084393199&partnerID=8YFLogxK
U2 - 10.1086/708270
DO - 10.1086/708270
M3 - Article
C2 - 32364792
AN - SCOPUS:85084393199
SN - 0003-0147
VL - 195
SP - 833
EP - 850
JO - American Naturalist
JF - American Naturalist
IS - 5
ER -