Analyzing heterogeneous landscapes to reveal ecological processes: the spatial modeling of forest-meadow ecotones using aerial photography

Undergraduate Honors Thesis

Citations

Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/cj82k796s

Abstract

Understanding the mechanisms that create mosaics of communities across broad landscapes is of general interest in ecology. However, in most landscapes, little is known about the mechanisms that drive these patterns, why ecotones form and where they do, and how they have been shaped by human disturbances and topographic patterns. In order to assess the spatial dynamics of forest-meadow ecotones, I conducted a spatial analysis, using GIS, to determine changes in the position of these boundaries, the change in tree cover, and the location and extent of patches of grassland vegetation over time based on historical aerial photos taken in 1938, 1953, 1985, 1990, 1999, 2002, 2004, 2005, 2006, 2008, and 2013. By using aerial imagery and GIS analysis, I will be able to quantify habitat changes for forests and meadows, at the final fine scales needed to better understand the stability or movement of ecotone boundaries. Over this 75 year time slice, there was a 82.3% increase in forest cover for Upper Elk Meadows. The recent encroachment of conifers into montane meadows may constitute one phase of a cyclical process that includes periods of forest expansion, retraction, or statis. However, this rapid conversion of meadow to forest, as seen in Elk Meadows, may signal a shift to an alternative stable state. Regardless of the causes of encroachment discussed above, it is important to maintain open meadow habitats, for both species biodiversity and other resource values.

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