Nitrogen dynamics of a nitrogen-saturated central Appalachian hardwood forest
- Marshall Univ. Huntington, WV (United States)
Recently, the potential for excess nitrogen (N) deposition to disrupt biogeochemical cycles, reduce water quality, and induce forest decline has been recognized. This study examined soil N dynamics in three watersheds of the Fernow Experimental Forest, West Virginia, which receive varying amounts of N depositions: WS7 (young control): WS4 (mature control); WS3 (young treatment). WS3 has received aerial applications of (NH{sub 4}){sub 2}SO{sub 4} for 5 yr at -3 x ambient N inputs. Mineral soil was incubated in situ every -30 d during the growing season in seven sample plots/watershed. Moist soil was analyzed for extractable N. Forest floor material and foliage of Viola blanda from each plot were analyzed for N and other nutrients. Soil organic matter and total soil N were determined. There were no significant differences among watersheds for total soil N, soil organic matter, and net nitrification and mineralization, but available N pools (NH {sup +}{sub 4} and NO{sup -}{sub 3}) were significantly higher on the treatment watershed than on the control watersheds. Seasonal patterns of N pools exhibited significantly higher NH{sup +} {sub 4} and NO{sup -}{sub 3} on Ws3 than on WS4 and WS7 from August to October. N availability indices (total soil and litter N, foliar N, net mineralization and nitrification, and NH{sup +}{sub 3} and NO{sup -} {sub 3} pools) were poorly correlated on WS3, whereas there were numerous correlations among these variables on WS4 and WS7. Results support an earlier conclusion that WS3 has become FN-saturated following 5 yr of treatment, and how that N saturation can result in elevated pools of both NH{sup +}{sub 4} and NO{sup -}{sub 3} in the mineral soil, suggesting that the process of N saturation may {open_quotes}de-couple{close_quotes} components of the N cycle in impacted forests and bypass the organic recycling of N by plant uptake of N, litter and fine root turnover, organic matter decomposition, and N mineralization nitrification.
- OSTI ID:
- 107101
- Report Number(s):
- CONF-9507129--
- Journal Information:
- Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 3 Vol. 76; ISSN BECLAG; ISSN 0012-9623
- Country of Publication:
- United States
- Language:
- English
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