Year: 2000
Type: dissertation
Abstract: Ecologists have recognized disturbance as an important driver of spatial patterns in a landscape and the composition of its species.Wildfire in particular has received special attention as a recurrent, ubiquitous disturbance that has greatly influenced the structure of Rocky Mountain forest ecosystems.However, in recent decades, staggered-setting clearcut logging has altered the spatial and temporal characteristics of historic landscape patterns driven by fire.Increasingly, landscape ecologists are using patterns of natural disturbance as a guide for ecosystem management.My study area in the Greater Yellowstone Ecosystem (GYE) contained patterns of intensive logging in the Targhee National Forest (TNF) directly adjacent to patterns resulting from wildfire in 1988 in Yellowstone National Park (YNP).To compare these disturbance types, I tested hypotheses at two scales.At the landscape scale, spatial patterns of clearcuts and wildfires were subsampled at various extents and quantified using landscape metrics.A finer-scaled field study focused on post-disturbance biological legacy within stands.Results indicate that clearcutting fragmented forests more than wildfire, reducing total core area, while increasing the number of core areas.Patch size, shape and dispersion all revealed differences between clearcutting and wildfire.Furthermore, multi-scaled frequency distributions of 9 landscape metrics revealed thresholds in scaling effects for each disturbance type.The field study demonstrated that clearcutting is a more severe disturbance type than wildfire, removing more CWD and dramatically reducing snag density.These differences between clearcutting and wildfire at both the landscape and stand scales have important ecological consequences for the natural fire regime.At the landscape scale, wildfire is constrained by the clearcutting pattern in TNF, whereas fire risk is higher in YNP.At the stand scale, clearcutting removes CWD and standing snags that provide fuel for future wildfires.Hence, clearcutting disrupts the natural disturbance regime.Recognizing this important consequence, timber harvest strategies can be developed that better mimic natural landscape patterns that perpetuate the natural disturbance regime and sustain levels of biodiversity.
Author: Henry Bond Wilmer
Language: English
Topic: Fire effects on ecosystems
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W157156739