Nitrous oxide emissions from forested and harvested ecosystems in northeastern Nova Scotia

Although studies have shown that deforestation alters the emissions of nitrous oxides (N2O) from forest soils in tropical environments, little is known about the northern temperate and boreal forests. This study monitored the N2O soil emissions from two 3 year old harvested and intact forest pairs of contrasting soil texture. The study was conducted through the late summer to early fall period in the Acadian forest of Atlantic Canada in order to quantify N2O emissions associated with each landuse type, and to determine the factors controlling these emissions. The suitability of a photoacoustic gas monitor (PGM) for in situ field measurements of this gas was also evaluated. Each site was equipped with 11 permanent collars for surface flux measurements designed to capture the microsite variability. Subsurface soil gas samplers were installed at depths of 0, 10, 20 and 35 cm below the organic-mineral soil interface. A nonsteady-state vented surface flux chamber coupled to the PGM was used to regularly measure the surface fluxes in order to quantify the soil-atmosphere N2O exchanges. The important zones of N2O production in the profile were identified by less frequent measurements of subsurface gas concentrations. Soil nitrogen, soil bulk density, and soil pH were measured at each site. Preliminary results reveal that spatial and temporal variability in surface emissions are very high and that there is a difference in the magnitude of fluxes between harvested and intact forest pairs