부산대학교 도서관

Forest harvesting alters the cycling of nitrogen (N) within temperate forest systems in a manner that may influence atmospheric nitrous oxide (NO) concentrations. This paper investigates, over a single growing season within the Acadian Forest region of Atlantic Canada, soil NO fluxes across a clearcut harvest red spruce forest chronosequence that includes an old growth reference site (>125 years). A pulse of soil NO at ~1-2 years was observed after clearcut harvesting, followed by an exponential decay to a baseline level within one to two decades after the harvesting event. No significant differences between fluxes from the forest sites >20 years of age and the reference old growth site (>125 years) were observed. Soils within the chronosequence acted as both sources and sinks for NO through the growing season. Low soil N availability was identified as the likely factor limiting soil NO flux responses to changes in soil temperature and moisture in situ at most sites. This was confirmed by controlled laboratory experiments that measured soil NO flux responses to moisture, temperature and N amendments. Without N amendments, soils act as an elevated sink for NO under increased temperature. However, when soil N was not limiting, NO flux responded primarily to moisture. Overall, the study suggests that moist temperate forest soils that are N-limited can act as a transient source of NO following clearcut harvesting during the growing season, and that the decrease in the release of NO from soils following harvesting follows an exponential pattern. [ABSTRACT FROM AUTHOR]