On-line version ISSN 0717-6643
GODOY, Roberto et al. Dry deposition of nitrogen to passive samplers in grassland and forest canopies in the Central depression of southern Chile. Gayana Bot. [online]. 2005, vol.62, n.2, pp. 110-119. ISSN 0717-6643. doi: 10.4067/S0717-66432005000200006.
The growth of intensive livestock farming in the central depression of southern Chile (40° S) during the last century has resulted in elevated emissions of inorganic nitrogen (N) compounds into the atmosphere, particularly of NH3. Consequently, atmospheric N has been deposited to lakes, vegetation, and soil. Much attention has been paid to wet N deposition in southern Chile, while almost nothing is known about dry N deposition in this region. Our aim is to use an exploratory approach with SAM (Standard Air Monitoring) filters to investigate the potential contribution of the dry N deposition to the total N deposition in the central depression of southern Chile. Furthermore, the relationship between micro-climatological patterns and dry deposition was studied, and dry deposition to passive samplers in grasslands was compared to the deposition to samplers in two forest canopies. Wet and dry deposition of N were measured during one year and six months, respectively, in a grassland area, a Nothofagus obliqua (Mirb.) Oerst. forest and a Pinus radiata D. Don. plantation located in the central depression of southern Chile. After twelve months, the wet atmospheric N deposition was 3.4 kg N ha-1, including organic and inorganic N fluxes, while the amount of dry deposited NH4-N on passive samplers in the grassland was 12.2 kg N ha-1 during six months. No clear seasonal pattern in wet deposition was found over the year and no trend in dry deposition appeared after six months of observation. The results reflect the large variations between the deposition of NH4-N to passive samplers in grassland and samplers within the canopy of Nothofagus forest and Pinus plantation. After inclusion of an estimate of dry deposited N, the atmospheric N load is greater than reported values for evergreen and deciduous forests in southern Chile
Keywords : Atmospheric deposition; nitrogen; Nothofagus obliqua forest; Pinus radiata plantation; surrogate surface.