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Nitrogen deposition and flux through three birch stands (Betula pubescens Ehrh.) in the Kampinos National Park (central Poland)

Kram K.

Polish Journal of Ecology

2008

Vol. 56, nr 4

605-612

Nitrogen flow through birch stand canopies was studied in the Kampinos National Park (large forested area with inland dunes and wetlands close to Warsaw) during the growing seasons (April-October) of 2005-2006. The amount of nitrogen deposition including main forms like NO[3], NH[4], organic N and the aerosolgaseous fraction of deposition were estimated as well as the influence of birch canopies on this process. Because a method of "artificial foliage" allows to measure an aerosol-gaseous fraction of deposition a gradient of rain collectors equipped with artificial foliage of known surfaces were used. The results were compared with amounts of nitrogen measured in the throughfall of three birch forests. All stands (age 20.50 years) were rather similar, but stand II has smaller LAI (Leaf Area Index = 2.5 m[^2] m[^-2]) than stands II and III (3.8 and 3.9 m[^2] m[-2]). It was found that nitrogen deposition in the Kampinos National Park is rather high - 1.6 kg ha[^-1] month[-1]. Ammoniumnitrogen made almost half of this value, organic nitrogen - over one third, and nitrate-nitrogen constituted the rest. Aerosol-gaseous input significantly made the deposition increased only in the case of nitrate-nitrogen, but deposition of ammonium- and organic nitrogen were similar and independent of catching leaf area. All fractions of nitrogen were effectively taken up during their passing through birch canopies (57% of nitrogen deposition was retained). Generally two thirds of deposited ammonium-nitrogen, more than half of organic N, and one third of nitratenitrogen were taken up by birch canopies. However, uptake efficiency of all N forms was lower for stand with smallest leaf area with no statistically significant retention of organic N.