Slovenian Forestry Institute, The Silva Slovenica Publishing Centre
Abstract
Open field bulk deposition of inorganic nitrogen (N-NO3 + N-NH4) measured at Level II sites in Italy over the period 2000-2011 ranged from 3.9 to 16.2 kg ha-1 per year. A positive effect on basal area increment and C sequestration was detected at the same sites (Ferretti et al. 2014), but uncertainty remains on the overall impact of N deposition on the Italian forests. Data on N deposition at national level are available only in the form of large-scale, emission based models with relatively coarse spatial resolution (EMEP model, 50 x 50 km), which may be not reliable, when scaled down to local scales. Here we attempted to use measured Level II data from the Italian network to: . Validate existing and freely available EMEP data; and . develop an independent, deterministic geo-statistical model based on actual data measured at Level II sites over the period 2000 - 2011. To validate existing model output we run a simple exercise comparing spatial and temporal pattern of measured and modelled N deposition in relation to those measured at the Level II sites. For the geo-statistical model, we used the following predictors: latitude, longitude, elevation, aspect, annual precipitation and land use within three different buffer ranges: 3, 16 and 50 km radius from the very plot. Here we present the first outputs of the study. These results will be used in three directions: to derive N deposition estimates for Level I plots (and other sites); to feed correlative studies on the effect of N deposition on forests; to re-design the Italian deposition monitoring program, in terms of number of sites and their spatial allocation (retrospective design)
