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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

Canadian Journal of Forest Research

By:
, ,
DOI: 10.1139/X08-092

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Abstract

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.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Four centuries of soil carbon and nitrogen change after stand-replacing fire in a forest landscape in the western Cascade Range of Oregon
Series title:
Canadian Journal of Forest Research
DOI:
10.1139/X08-092
Volume
38
Issue:
9
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Canadian Journal of Forest Research
First page:
2455
Last page:
2464