Exchange of trace gases between soils and the atmosphere in Scots pine forest ecosystems of the northeastern German lowlands 2. A novel approach to scale up N2O- and NO-fluxes from forest soils by modeling their relationships to vegetation structure

摘要

Micro-scale emission rates of the primary and secondary relevant atmospheric greenhouse gases N2O and NO from forest soils of northeast German Scots pine plantations are demonstrated to be highly dependent on the patterns of ground vegetation within the measuring chambers as well as on the canopy structure above the measuring plots. Based on an extensive statistical analysis of these dependencies, a model is developed allowing to predict N-trace gas emissions of different ecosystem types of mature Scots pine stands by applying an area-weighted averaging of local flux rates. The horizontal distribution patterns of emissions within the stands follow the small-scale distribution of N-deposition and precipitation controlled mainly by canopy structure. The mean emission rates of N2O and NO are strongly dependent on top-soil state and vegetation-indicated by the vegetation type-and the atmospheric N-deposition. These findings open up the possibility to calculate N emissions from forest soils on a regional scale. Furthermore, the model predicts an increase of N2O-emissions from forest soil with increasing thinning of stands.