| Popis: |
In terrestrial ecosystems, nitrogen in soil water has mainly been considered in its inorganic plant available forms (NH4, NO3). Only few studies in forests have included the dissolved organic nitrogen fraction (e.g. Koopmans et al. 1996), although DON may be the dominant N form in soil water in many ecosystems (Sollins and McCorison 1981; Qualls et al. 1991). DON accounted for 95% of N losses in streams in an undisturbed natural temperate forest at pristine conditions in Chile (Hedin et al. 1995). Nitrogen losses in deep percolating soil water amounted to 2.2kg N ha−1 a−1 in both spruce and beech at Solling, Germany (Matzner 1988), a region with much higher atmospheric depositions. |
