Linking patch dynamics, landscape organization, patch-size scaling, and landscape connectivity

Abstract

Over time, small local disturbances may result in large regional changes in landscape structure and function. For example, lightning strikes may lead to large-scale wildfire or land clearing to urbanization. In either case, landscape patterns change as the type and distribution of landscape elements change in response to disturbances. Additionally, changes in landscape patterns often affect ecological processes. For example, wildfires and urbanization affect succession and productivity, which changes the distribution of habitat features, and which may affect landscape connectivity for species inhabiting the landscape. I used rank-size distributions and their scaling exponents to illustrate landscape character and change in Yellowstone National Park and a portion of the metropolitan area of Tucson, Arizona, through patterns associated with the distribution of patch size. I found that natural and anthropogenic disturbances affected landscape organization similarly and thus produced similar distributional patterns of patch size. However, the magnitude of change created by natural and anthropogenic disturbances differed. Fires in Yellowstone National Park produced scaling exponents >1, suggesting that large patches affected the distribution of patch size disproportionately. Comparatively, urbanization in the Tucson metropolitan area produced scaling exponents ≈1, suggesting that large and small patches affect the distribution of patch size proportionately. To link changes in landscape patterns with changes in ecological processes I compared four commonly used landscape metrics with rank-size distributions and their scaling exponents. Rank-size distributions described the scaling properties of the landscape with regard to patch size, whereas other metrics did not. This is meaningful because there is an integral relationship between scaling properties of the landscape and scaling properties of species using the landscape. A species may perceive a landscape as connected when the patch-size characteristics of the landscape scale proportionally with the body-size characteristics of the species. As a result, the species may be more likely to move through and therefore persist in that landscape. I develop a theoretical relationship between natural and anthropogenic disturbances, describe landscape organization, and link landscape and species scaling characteristics.