Landscape Assessment of Browse and Fire Effects on Aspen Woodland Habitat in the Centennial Valley, Gye, Montana
Event Website
http://www.nafew2009.org/
Start Date
6-23-2009 9:20 AM
End Date
6-23-2009 9:40 AM
Description
In the Greater Yellowstone Ecosystem, aspen woodlands represent a low proportion of total cover, but these habitats support disproportionately high biological diversity. The extent of aspen woodlands in the Centennial Valley has declined significantly over the past century due to increased conifer density and extent, both associated with fire exclusion. The primary management response is to restore fire through “Appropriate Management Response” policies or prescribed fires. If aspen sprouts are subjected to intense and chronic browsing by wildlife, a fire that kills overstory aspen trees may actually result in loss of resilience and even death of aspen clones. Prior to a series of planned, prescribed fires across the Centennial landscape, we examined browse effects, stand structure, and historic stand conditions at 205 randomly sampled sites across eight study areas, including the 2003 Winslow Burn. Within the burned area, the mortality of conifer trees and overstory aspen released prolific sprouting, but ubiquitous browsing by wild ungulates prevented sprouts from exceeding browse height or replacing overstory trees, except adjacent to major roads. Browse effects were similarly intense across several of the study areas where prescribed fires are proposed. Stand structure within aspen woodlands demonstrated continued replacement by Douglas-fir in 75% of stands sampled. We also documented aspen coarse wood where no living above-ground growth could be found, suggesting death of clones at 6% of sampled sites. Subsequent measures suggest browse effects change over time and may be linked to seasonal weather patterns. The distribution and behavior of wildlife has changed due to land use and wolf removal; managers must recognize the risks and uncertainties associated with restoring fire to systems that are fundamentally different from the past. Continued monitoring will be a critical component for implementing fire plans in the Centennial Valley to ensure management activities meet ecological objectives.
Landscape Assessment of Browse and Fire Effects on Aspen Woodland Habitat in the Centennial Valley, Gye, Montana
In the Greater Yellowstone Ecosystem, aspen woodlands represent a low proportion of total cover, but these habitats support disproportionately high biological diversity. The extent of aspen woodlands in the Centennial Valley has declined significantly over the past century due to increased conifer density and extent, both associated with fire exclusion. The primary management response is to restore fire through “Appropriate Management Response” policies or prescribed fires. If aspen sprouts are subjected to intense and chronic browsing by wildlife, a fire that kills overstory aspen trees may actually result in loss of resilience and even death of aspen clones. Prior to a series of planned, prescribed fires across the Centennial landscape, we examined browse effects, stand structure, and historic stand conditions at 205 randomly sampled sites across eight study areas, including the 2003 Winslow Burn. Within the burned area, the mortality of conifer trees and overstory aspen released prolific sprouting, but ubiquitous browsing by wild ungulates prevented sprouts from exceeding browse height or replacing overstory trees, except adjacent to major roads. Browse effects were similarly intense across several of the study areas where prescribed fires are proposed. Stand structure within aspen woodlands demonstrated continued replacement by Douglas-fir in 75% of stands sampled. We also documented aspen coarse wood where no living above-ground growth could be found, suggesting death of clones at 6% of sampled sites. Subsequent measures suggest browse effects change over time and may be linked to seasonal weather patterns. The distribution and behavior of wildlife has changed due to land use and wolf removal; managers must recognize the risks and uncertainties associated with restoring fire to systems that are fundamentally different from the past. Continued monitoring will be a critical component for implementing fire plans in the Centennial Valley to ensure management activities meet ecological objectives.
https://digitalcommons.usu.edu/nafecology/sessions/aspen/9