Rate and pattern of forest disturbance in the Klamath-Siskiyou ecoregion,USA between 1972 and 1992

We classified NALC (North American Landscape Characterization) imagery to forest-nonforest and examined forest change between 1972 and 1992 in theKlamath-Siskiyou ecoregion (USA) in relation to land ownership and fifth levelwatersheds. We also analyzed changes in forest patterns by land ownership forthree major river basins within the ecoregion (Eel, Klamath, and Rogue) usingFRAGSTATS. Overall, forests covered 66.8% of the ecoregion in 1972 and 62.1% in1992. Approximately 10.5% of the forest area was disturbed overall, translatinginto an annual disturbance rate of 0.53%. Although public lands accounted for aslightly higher total area of forest disturbance, private lands were cut at aslightly higher rate. Forest disturbance within fifth level watersheds averaged13.2%, but reached as high as 93.2%. For the three river basins where spatialpattern of forest disturbance was analyzed, private lands were already morefragmented than public lands in 1972. Over the 20-year time period, forestfragmentation increased on all ownerships. Fragmentation rates on public landswere high for all basins especially the Rogue. Clearcut logging on privatelandswas generally in larger adjacent tracts, whereas cuts on public lands weregenerally smaller and more dispersed. Our results illustrate the importance ofconsidering landscape change history when planning for effective biodiversityconservation in forested ecoregions and when formulating ecologicallysustainable forest management strategies.This revised version was published online in May 2005 with corrections to the Cover Date.