Edge fires drive the shape and stability of tropical forests |
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| Authors: | Laurent Hébert‐Dufresne Adam F A Pellegrini Uttam Bhat Sidney Redner Stephen W Pacala Andrew M Berdahl |
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| Institution: | 1. Department of Computer Science and Vermont Complex Systems Center, University of Vermont, Burlington, VT, USA;2. Santa Fe Institute, Santa Fe, NM, USA;3. Department of Earth System Science, Stanford University, Stanford, CA, USA;4. Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA;5. Department of Physics, Boston University, Boston, MA, USA;6. School of Natural Sciences, University of California, Merced, Merced, CA, USA;7. School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA |
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| Abstract: | In tropical regions, fires propagate readily in grasslands but typically consume only edges of forest patches. Thus, forest patches grow due to tree propagation and shrink by fires in surrounding grasslands. The interplay between these competing edge effects is unknown, but critical in determining the shape and stability of individual forest patches, as well the landscape‐level spatial distribution and stability of forests. We analyze high‐resolution remote‐sensing data from protected Brazilian Cerrado areas and find that forest shapes obey a robust perimeter–area scaling relation across climatic zones. We explain this scaling by introducing a heterogeneous fire propagation model of tropical forest‐grassland ecotones. Deviations from this perimeter–area relation determine the stability of individual forest patches. At a larger scale, our model predicts that the relative rates of tree growth due to propagative expansion and long‐distance seed dispersal determine whether collapse of regional‐scale tree cover is continuous or discontinuous as fire frequency changes. |
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| Keywords: | Bistability edge effects fire forest savanna scaling |
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