Friday, August 8, 2008: 8:20 AM
101 A , Midwest Airlines Center
Background/Question/Methods Mountain meadows of the Pacific Northwest play important ecological roles and societal functions but are experiencing invasion by trees. Land managers are examining methods to maintain or restore meadows through tree removal. However treatment of the resultant logging slash poses both logistical and ecological challenges. At Bunchgrass Ridge, in the western Cascade Mountains of Oregon, pile burning was used as one of two methods of slash disposal in larger study of meadow restoration. My research examined initial effects of pile burning on vegetation and soils and whether these effects extended beyond the burn scar into adjacent vegetation. Following removal of lodgepole pine and grand fir from three 1-ha experimental plots, slash was moved into piles 2-3 m tall and 2-4 m in diameter. Fall burning resulted in nearly complete (95-100%) consumption of woody material. Ground conditions, vegetation composition, and soil chemistry were sampled during the following growing season in a series of 20 x 50 cm quadrats placed centrally, at the edge, and adjacent to 30 burn piles.
Results/Conclusions Burn scars had a central area where intense heating occurred leaving white ash or reddened mineral soil. At greater distance from the center, burning was less intense, leaving blackened duff and exposing little mineral soil. Burning had no effect on ground conditions adjacent to the scar. Centers of burn scars were characterized by highly elevated concentrations of available N and higher pH, but total C and N did not differ from soils at the edge or in adjacent unburned vegetation. Plants were absent from the centers of burn scars and were greatly reduced in cover and richness at the edge. However, burn effects did not extend beyond the scar. Surprisingly, ruderal species were uncommon. Although burn piles can be used effectively to reduce fuel loading under controlled conditions, local effects of burning can be severe. Initial survival of vegetation within the edges of burn scars and limited establishment of ruderals suggest that natural revegetation may be possible over time. However, longer-term observations are needed to assess the full potential for recovery.
Results/Conclusions Burn scars had a central area where intense heating occurred leaving white ash or reddened mineral soil. At greater distance from the center, burning was less intense, leaving blackened duff and exposing little mineral soil. Burning had no effect on ground conditions adjacent to the scar. Centers of burn scars were characterized by highly elevated concentrations of available N and higher pH, but total C and N did not differ from soils at the edge or in adjacent unburned vegetation. Plants were absent from the centers of burn scars and were greatly reduced in cover and richness at the edge. However, burn effects did not extend beyond the scar. Surprisingly, ruderal species were uncommon. Although burn piles can be used effectively to reduce fuel loading under controlled conditions, local effects of burning can be severe. Initial survival of vegetation within the edges of burn scars and limited establishment of ruderals suggest that natural revegetation may be possible over time. However, longer-term observations are needed to assess the full potential for recovery.
