Nitrogen deposition in Mediterranean forests.
Atmospheric deposition of inorganic nitrogen was studied at two forested sites in the Montseny mountains (northeast Spain), peripheral to the Barcelona conurbation, and at a nearby lowland town, using bulk deposition, wet-only deposition, throughfall, and dry deposition inferred from branch-washes and surrogate surfaces (metacrylate plates). Bulk deposition inputs of ammonium and nitrate did not show significant temporal trends over a 16-year period. Bulk inputs of inorganic N were moderate, ranging from 6 to 10 kg N ha(-1) year(-1) depending on the time period considered and the degree of site exposure to polluted air masses from the Barcelona conurbation. Large dry-sedimented particles played a minor role, since wet-only inputs were virtually identical to bulk inputs. On the contrary, branch- and plate-washes indicated substantial dry inputs of N gases and small particles. Total atmospheric deposition was estimated at 15-22 kg N ha(-1) year(-1), most of it being retained within the studied broadleaved evergreen forests. Ecosystem N availability is thus likely to be increasing in these forests.
Rodà
F
F
Center for Ecological Research and Forestry Applications, Universitat Autònoma de Barcelona, Bellaterra, Spain. roda@uab.es
Avila
A
A
Rodrigo
A
A
D000393:Air Pollutants / Q000032:analysis*; D001682:Biological Availability; D017753:Ecosystem; D004784:Environmental Monitoring; D005740:Gases; D019015:Geologic Sediments / Q000737:chemistry; D019083:Mediterranean Region; D009584:Nitrogen / Q000032:analysis*; D010316:Particle Size; D014197:Trees
D000393:Air Pollutants; D005740:Gases; D009584:Nitrogen