Woody Fuel Structure and Fire in Subalpine Fir Forests, Olympic National Park, Washington

Document Type


Journal/Book Title/Conference

Canadian Journal of Forest Research

Publication Date






First Page


Last Page



The fuel structure and flammability of fire-resilient subalpine fir (Abies lasiocarpa) stands in Washington were studied in 1987 to determine the relation between these forests and fire; for comparison, fuel patterns were also studied in fire-stable ponderosa pine (Pinus ponderosa) stands. It has long been known that subalpine fir forests burn catastrophically, but the contributions of fuel structure and fuel moisture to this pattern of burning have been relatively unstudied. The two main findings of the study were as follows: (1) more than twice as much fuel in subalpine fir forests accumulated around the bases of the fir trees than in the forest as a whole, and the many dead branches on the lower boles may allow fire to travel up into the canopy; (2) the fuels in subalpine fir forests were more flammable at the end of the summer than at the beginning, with maximum flammability in early August when the fuel moisture content was 16-22%. The fuel structure of subalpine fir was shown to be different from that of fire-stable ponderosa pine forests: the fuel around the bases of the trees in ponderosa pine forests was not significantly different from that in the entire forest, and there were few branches on the lower boles.