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Nitrogen dynamics post-harvest: the role of woody residues

Informally Refereed

Abstract

The role of woody residues in N dynamics in harvested forests has not been fully elucidated. Woody residues have been found to be an N sink, N source, and N neutral in different studies. To understand the implications of each of these scenarios, post-harvest N dynamics in high- and no- woody residue treatments were modeled for a Douglas-fir ecosystem. Nitrogen mineralization in the combined forest floor, soil (to 15 cm depth), and root pools was 122 and 121, kg N/ha/year, in years 1 and 2 after harvest, independent of treatment. When wood was an N sink, 23 kg N/ha/year could be immobilized annually, and about 80 and 100 percent of the N available from forest floor, soil, and roots remained plant or leaching available in high- and no- woody residue treatments, respectively. When wood was a source of N, an additional 12 kg N/ha/year became available from wood in high residue, and 0 in no residue treatment. When wood was neutral, 100 percent of the N mineralized after harvest was plant and/or leaching available in both treatments. Empirical evidence is still necessary to confirm which scenario operates in various forest ecosystems. Implications of these different scenarios for N-saturated ecosystems of the central Appalachians are that as N sink, woody residues could potentially help decrease N exports as nitrate. As N source, woody residues could contribute to N exports. As neutral, woody residues would allow exports of N as they currently occur. This paper reflects on the dynamics of N and woody residues in the Appalachian hardwood forests and provide hypothetical comparisons between these dynamics in western coniferous forests and eastern hardwood forests.

Parent Publication

Citation

Piatek, Kathryn. 2007. Nitrogen dynamics post-harvest: the role of woody residues. e-Gen. Tech. Rep. SRS–101. U.S. Department of Agriculture, Forest Service, Southern Research Station: 129-134 [CD-ROM].
https://www.fs.usda.gov/research/treesearch/27816