FIRE HISTORY ALONG AN ELEVATIONAL GRADIENT IN THE SISKIYOU MOUNTAINS, OREGON

Fire history was investigated at two sites in the Siskiyou Mountains of southern Oregon. Kinney Creek in the eastern Siskiyous and Oregon Caves National Monument in the central Siskiyous span an elevational gradient from the Mixed Evergreen zone through the White Fir (Abies concolor) zone. The fire frequency of the forest around Kinney Creek, based on fire scars, was about 16 years between 1760 and 1860. Photographic evidence in 1916 of fires from 1854 to 1915 was difficult to corroborate in 1988 based on vegetation evidence. Oregon Caves fire history, reconstructed using a conservative natural fire rotation technique, was 37 years during 1650-1930 for the lower elevation Douglas-fir/oak (Pseudotsuga menziesii/Lithocarpus-Quercus spp.) community and 64 years for the highest elevation white fir/herb community, with substantial variation by century. The fire-free interval since 1921 is the longest in more than 300 years. These old-growth forests developed with a much more frequent disturbance history than the wetter, cooler Douglas-fir forests of the Olympic and Cascade Mountains of Washington.