Transition from connected to fragmented vegetation across an environmental gradient: scaling laws in ecotone geometry
Gastner, Michael T., Oborny, Beata, Zimmermann, D. K. and Pruessner, Gunnar. (2009) Transition from connected to fragmented vegetation across an environmental gradient: scaling laws in ecotone geometry. American Naturalist, Vol.174 (No.1). E23-E39. ISSN 0003-0147
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Official URL: http://dx.doi.org/10.1086/599292
A change in the environmental conditions across space—for example, altitude or latitude—can cause significant changes in the density of a vegetation type and, consequently, in spatial connectivity. We use spatially explicit simulations to study the transition from connected to fragmented vegetation. A static (gradient percolation) model is compared to dynamic (gradient contact process) models. Connectivity is characterized from the perspective of various species that use this vegetation type for habitat and differ in dispersal or migration range, that is, “step length” across the landscape. The boundary of connected vegetation delineated by a particular step length is termed the “ hull edge.” We found that for every step length and for every gradient, the hull edge is a fractal with dimension 7/4. The result is the same for different spatial models, suggesting that there are universal laws in ecotone geometry. To demonstrate that the model is applicable to real data, a hull edge of fractal dimension 7/4 is shown on a satellite image of a piñon‐juniper woodland on a hillside. We propose to use the hull edge to define the boundary of a vegetation type unambiguously. This offers a new tool for detecting a shift of the boundary due to a climate change.
|Item Type:||Journal Article|
|Subjects:||Q Science > QK Botany
Q Science > QA Mathematics
|Divisions:||Faculty of Science > Mathematics|
|Library of Congress Subject Headings (LCSH):||Fractals -- Research, Dimension theory (Topology), Timberline -- Mathematical models, Landscapes -- Mathematical models, Forest dynamics -- Data processing|
|Journal or Publication Title:||American Naturalist|
|Publisher:||University of Chicago Press|
|Official Date:||July 2009|
|Access rights to Published version:||Restricted or Subscription Access|
Allen, C. D., and D. D. Breshears. 1998. Drought-induced shift of a forest-woodland ecotone: rapid landscape response to climate variation. Proceedings of the National Academy of Sciences of the USA 95:14839–14842.
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