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Old growth in the frequent-fire conifer forests of the western United States, such as those containing ponderosa pine (Pinus ponderosa), Jeffrey pine (P. jeffreyi), giant sequoia (Sequioa giganteum) and other species, has undergone major changes since Euro-American settlement. Understanding past changes and anticipating future changes under different potential management scenarios are fundamental to developing ecologically based fuel reduction or ecological restoration treatments. Some of the many changes that have occurred in these forests include shifts from historically frequent surface fire to no fire or to stand-replacing fire regimes, increases in tree density, increased abundance of fire-intolerant trees, decreases in understory productivity, hydrological alterations, and increased accelerated mortality of old trees. Although these changes are widespread, the magnitude and causes of changes may vary within and among landscapes. Agents of change, such as fire exclusion or livestock grazing, likely interacted and had multiple effects. For example, historical ranching operations may have altered both fire regimes and understory vegetation, and facilitated institutional fire exclusion through fragmentation and settlement. Evidence exists for large variation in presettlement characteristics and current condition of old growth across this broad forest region, although there are many examples of striking similarities on widely distant landscapes. Exotic species, climate change, unnatural stand-replacing wildfires, and other factors will likely continue to degrade or eradicate old growth in many areas. As a policy of fire exclusion is proving to be unsustainable, mechanical tree thinning, prescribed fire or wildland fire use will likely be key options for forestalling continued eradication of old growth by severe crown fires. For many practical and societal reasons, the wildland-urban interface may afford some of the most immediate opportunities for re-establishing old growth typical of presettlement forests resistant to crown fires. © 2007 by the authors. Published here under license by the Resilience Alliance.
Cataloging Information
- Arizona
- catastrophic fires
- Colorado
- coniferous forests
- conservation
- crown fires
- ecological restoration
- ecosystem dynamics
- evolutionary environment
- fire exclusion
- fire frequency
- fire hazard reduction
- fire intensity
- fire management
- fire regimes
- forest management
- fragmentation
- grazing
- hydrology
- livestock
- management
- mixed conifer
- Montana
- mortality
- national parks
- New Mexico
- old growth forests
- Pinus jeffreyi
- Pinus jeffreyi
- Pinus ponderosa
- Pinus ponderosa
- population density
- predation
- Pseudotsuga menziesii
- range of variability
- Sequoia
- Sequoia giganteum
- Sequoiadendron giganteum
- soils
- stand characteristics
- surface fires
- Texas
- thinning
- trees
- understory vegetation
- Utah
- Washington
- watersheds
- wildfires
- wildlife
This bibliographic record was either created or modified by Tall Timbers and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of Tall Timbers.