DENITRIFICATION OF AN UPLAND FOREST SITE

Rates of nitrogen loss through denitrification were monitored for standing forest and adjacent clear-felled areas located on a peaty-gley soil at Kershope Forest in the north of England, in two year-long studies. The rates of denitrification in soil cores brought back to the laboratory were determined using the acetylene (C2H2) block technique. An equation relating denitrification to temperature was applied to derive an estimate for the monthly loss of nitrogen via denitrification from the sites. In an additional study, half of the cores were incubated in the absence of C2H2, so that an estimate of the ratio of emission of N2O/N2 could be made. An annual loss of 1–3 kg N ha-1 y-1 was estimated for the standing forest while losses from the clearfelled sites were estimated at 10–40 kg N ha-1 y-1 during the first 2 years after felling. This loss returned to pre-felling levels 4 years after felling. The results are discussed in relation to other studies of denitrification in forest soils and to the rates of N2O being lost to the atmosphere by UK forests. © 1990, Oxford University Press. All rights reserved.