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Four centuries of soil carbon and nitrogen change after stand-replacing fire in a forest landscape in the western Cascade Range of Oregon

September 28, 2010

Episodic stand-replacing wildfire is a significant disturbance in mesic and moist Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests of the Pacific Northwest. We studied 24 forest stands with known fire histories in the western Cascade Range in Oregon to evaluate long-term impacts of stand-replacing wildfire on carbon (C) and nitrogen (N) pools and dynamics within the forest floor (FF, Oe and Oa horizons) and the mineral soil (0-10 cm). Twelve of our stands burned approximately 150 years ago ('young'), and the other 12 burned approximately 550 years ago ('old'). Forest floor mean C and N pools were significantly greater in old stands than young stands (N pools: 1823 ?? 132 kg??ha-1 vs. 1450 ?? 98 kg??ha -1; C pools: 62 980 ?? 5403 kg??ha-1 vs. 49 032 ?? 2965 kg??ha-1, mean ?? SE) as a result of significant differences in FF mass. Forest floor C and N concentrations and C/N ratios did not differ by time since fire, yet potential N mineralization rates were significantly higher in FF of old sites. Old and young mineral soils did not differ significantly in pools, concentrations, C/N ratios, or cycling rates. Our results suggest that C and N are sequestered in FF of Pacific Northwest Douglas-fir forests over long (???400 year) intervals, but that shorter fire return intervals may prevent that accumulation. ?? 2008 NRC.

Citation Information

Publication Year 2008
Title Four centuries of soil carbon and nitrogen change after stand-replacing fire in a forest landscape in the western Cascade Range of Oregon
DOI 10.1139/X08-092
Authors T.W. Giesen, S.S. Perakis, K. Cromack
Publication Type Article
Publication Subtype Journal Article
Series Title Canadian Journal of Forest Research
Series Number
Index ID 70000195
Record Source USGS Publications Warehouse
USGS Organization Forest and Rangeland Ecosystem Science Center