The History Of Fire In The Bull Run Watershed Oregon

Author : Kelli J. Van Norman
Publisher :
ISBN 13 :
Total Pages : 206 pages
Book Rating : 4.:/5 (46 download)

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Download or read book Historical Fire Regime in the Little River Watershed, Southwestern Oregon written by Kelli J. Van Norman and published by . This book was released on 1998 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Disturbances are a prevalent and important part of ecosystems. Many landscape patterns that we find today were created, maintained, and changed by natural disturbance regimes. This is especially true for fire, which has historically been a common, natural disturbance in the western U.S forests and grasslands and many other parts of the globe. I reconstructed fire history and interpreted fire regime in 117 clearcuts distributed throughout a 45,000 ha study area within the Little River watershed, an Adaptive Management Area in southwestern Oregon. Tree rings were counted on over 3,000 stumps and provided a 683-year record of fire. The study area fire regime can be characterized by its variability. The composite median fire return interval for the study area was approximately 123 years. Fire extents were not estimated, but historical fires tended to be relatively small, usually occurring within less than 2.5 km. Low and moderate severity surface fires appeared to have been more common than stand-replacement fires indicating a moderate severity fire regime with much spatial variability in severity. The fire regime has changed temporally and spatially over the fire history record. Five distinct changes in the rate of fire occurrence were identified (1490-1569, 1570- 1844, 1845-1899, 1900-1925, and 1926-1996) and associated with changes in climate and human fire ignition and fire suppression. Fires were dispersed throughout the study area, probably due to dispersed lightning ignitions and small fire extents. As a result, fire frequency was wealdy correlated with topography. However, during the 1845-1899 time period, more fires occurred at low elevations, suggesting an influence of Euro-American settler fire ignitions.