Impact of atmospheric nitrogen deposition on carbon dynamics in two scots pine forest soils in Northern Germany.
The impact of atmospheric N deposition on the dynamics of various carbon fractions were investigated in two Scots pine forest soils (cambisol, podzol) of Northern Ger-many. Total organic carbon (TOC), CO2 emission, microbial carbon (Cmic) as well as organic hot- and coldwater extractable carbon fractions (Chwe, Ccwe) were analyzed before, during, and after the soil incubation study. On both sites, the N treatment showed no response to total organic carbon (TOC) contents in most of the investi-gated soil layers. Microbial carbon (Cmic) was significantly increased in the organic layer of both soil types by the N application. Subsequent to the N application, the CO2 emission increased in all mineral soil layers of the cambisol but remained almost unaffected in the podzol. After the N application, a remarkable increase of hotwater extractable C (Chwe) was detected for the organic layer of the cambisol but not for the podzol, whereas decreasing contents were established for coldwater extractable C (Ccwe) of both sites. The N application had not a significant impact on the leachate concentrations of total organic carbon (TOC), dissolved organic carbon (DOC), and particulate organic carbon (POC) in the podzol, whereas the concentrations of these C fractions were decreased in the organic layer and the 35 70 cm mineral soil layer of the cambisol.
The N treatment changed the contents of most of the investigated C fractions in both soil types and resulted in a considerable C mobilization. But the processes of the C mobilization between the cambisol and the podzol were completely different. Ac-cording to the presented data, the cambisol obtaining moderate atmospheric N loads is much more sensitive to additional N inputs than the podzol that already received high amounts of atmospheric N.
Scheuner, E.T.; Makeschin, F. 2004. Impact of atmospheric nitrogen deposition on carbon dynamics in two scots pine forest soils in Northern Germany. Plant and Soil. (in print)