Long-term effects of stump harvesting and site preparation on pools and fluxes of soil carbon and nitrogen in central Sweden

Abstract

ABSTRACTClear-cutting and subsequent site preparation is a common forest management practice in the Nordic countries. Slash and stumps have been suggested to replace fossil fuels in district heating plants. Stump/root removal from clear-cuts will reduce the amount of decomposable substrate in the soil and thus decrease soil CO2 emission, but stump lifting is also supposed to stimulate CO2 efflux and counteract CO2 reduction. To determine the effects of stump/root harvesting in relation to site preparation (stumps retained) on pools and fluxes of carbon (C) and nitrogen (N) after a period of 20–30 years, soil sampling was performed in four pairs of stump/root harvesting (S) and patch scarification (P) stands in central Sweden in 2009. Stump/root harvesting resulted in a significantly lower soil C pool in the humus layer. Annual heterotrophic respiration (RH) in the whole soil profile was significantly lower after the S than after the P treatment, the mean difference being 38 ± 23 g CO2–C m−2 year−1 (95% CI). This difference was larger than corresponding data from stump/root decomposition models (11–18 g CO2–C m−2 year−1), but both empirical and model data showed that stump/root harvesting will reduce heterotrophic soil CO2 emissions to the atmosphere during the actual period.