Dissertation Research: Ecological Effects of Temporal and Spatial Variability in the Disturbance Regime of an Old-growth Ponderosa Pine Forest

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Proposal: DEB-0105155PI: Swetnam, Thomas W., and Donald A. FalkTitle: Dissertation Research: Ecological Effects of Temporal and Spatial Variability in the Disturbance Regime of an Old-growth Ponderosa Pine ForestAlthough southwestern forests historically have been subjected to a disturbance regime that includes frequent fires, many tree species are sensitive to fire, especially during juvenile states of development. Paradoxically, fires occurring at mean intervals should exclude even dominant species such as Ponderosa Pine. This suggests that extended intervals without fire are required for the establishment of Ponderosa pine and other fire-sensitive species. Within this context, the proposed research addresses central issues in disturbance ecology with important implications to forestry and resource management. The effects of temporal variation in fire-return intervals are investigated with respect to the demography of dominant and sub-dominant species of tree, as this can have a significant impact on forest diversity. In addition, mathematical models are developed which consider the likelihood of fires occurring within a specified area. This provides quantitative insights concerning the scaling of effects for disturbance.