Quantitative Evidence for Increasing Forest Fire Severity in the Sierra Nevada and Southern Cascade Mountains, California and Nevada, USA

• Published in: Ecosystems (New York) Vol. 12; no. 1; pp. 16 - 32
• Main Authors: Miller, J. D, Safford, H. D, Crimmins, M, Thode, A. E
• Format: Journal Article
• Language: English
• Published: New York New York : Springer-Verlag 01.02.2009; Springer Science+Business Media; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Carbon sequestration; Climate models; climatic factors; Coniferous forests; Ecology; Ecosystems; Environmental impact; Environmental Management; Erosion rates; fire ecology; Fire severity; Forest & brush fires; Forest and land fires; Forest ecology; Forest ecosystems; Forest fires; Forest management; Forest service; forest types; Forestry; Fundamental and applied biological sciences. Psychology; General aspects; Geoecology/Natural Processes; Habitat availability; Hydrology/Water Resources; image analysis; Landsat; Life Sciences; montane forests; Mountains; Phytopathology. Animal pests. Plant and forest protection; Plant Sciences; Reforestation; relative differenced Normalized Burn Ratio; remote sensing; Seedlings; spatial data; statistical analysis; Synecology; temporal variation; Vegetation; vegetation cover; vegetation structure; Weather damages. Fires; Wildfires; Wildlife habitats; Zoology; Sierra Nevada region (California); Western United States; Cascade Mountain region; Nevada; United States; North America; America; USA, Cascade Mts; USA, California, Sierra Nevada Mts; USA, Nevada; USA, California; Sierra Nevada Forest Plan Amendment; burn severity; Sierra Nevada; fire severity; California; fire ecology; relative differenced Normalized Burn Ratio; Forests; Southern California; Amendment; Fire ecology; Cascade Range; Ecosystem; Ratio; Forest fire
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-008-9201-9

Recent research has concluded that forest wildfires in the western United States are becoming larger and more frequent. A more significant question may be whether the ecosystem impacts of wildfire are also increasing. We show that a large area (approximately 120000 km²) of California and western Nevada experienced a notable increase in the extent of forest stand-replacing (“high severity”) fire between 1984 and 2006. High severity forest fire is closely linked to forest fragmentation, wildlife habitat availability, erosion rates and sedimentation, post-fire seedling recruitment, carbon sequestration, and various other ecosystem properties and processes. Mean and maximum fire size, and the area burned annually have also all risen substantially since the beginning of the 1980s, and are now at or above values from the decades preceding the 1940s, when fire suppression became national policy. These trends are occurring in concert with a regional rise in temperature and a long-term increase in annual precipitation. A close examination of the climate-fire relationship and other evidence suggests that forest fuels are no longer limiting fire occurrence and behavior across much of the study region. We conclude that current trends in forest fire severity necessitate a re-examination of the implications of all-out fire suppression and its ecological impacts.