Title: Fine-root decomposition and N dynamics in coniferous forests of the Pacific Northwest, U.S.A.
Abstract: We examined the effects of species, initial substrate quality, and site differences (including temperature, precipitation, and soil N availability) on fine-root (<2 mm diameter) decomposition in litter bags and its N dynamics in Sitka spruce (Picea sitchensis (Bong) Carrière), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) forests in Oregon, U.S.A. Species significantly influenced fine-root mass loss during the first 2 years of decomposition. Over the same period, site differences had little impact on decomposition of fine roots. The percentage of initial mass remaining of decomposing fine roots fitted a single-exponential model. The decomposition rate constant (k) for all 15 species examined ranged from 0.172 year 1 for Engelmann spruce (Picea engelmanni Parry ex Engelm.) to 0.386 year 1 for Oregon ash (Fraxinus latifolia Benth.). Initial C quality indices (e.g., cellulose concentration, lignin concentration) of fine roots were correlated with fine-root decomposition rates. In contrast, initial N concentration and soil N availability were not correlated with fine-root decomposition rates. The rate of N released from decomposing roots was positively correlated with the initial N concentration of the fine roots. The data suggest that decomposing fine roots could release at least 20 kg N/ha annually in mature Douglas-fir forests of the Pacific Northwest.
Publication Year: 2002
Publication Date: 2002-02-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 113
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