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Solinger, Stephan ; Kalbitz, Karsten ; Matzner, Egbert:
Controls on the dynamics of dissolved organic carbon and nitrogen in a Central European deciduous forest.
In: Biogeochemistry.
Bd. 55
(2001)
.
- S. 327-349.
ISSN 1573-515X
DOI: https://doi.org/10.1023/A:1011848326013
Abstract
Despite growing attention concerning the role of dissolved organic matter (DOM)in element cycling of forest ecosystems, the controls of concentrations and fluxes of bothdissolved organic carbon (DOC) and nitrogen (DON) under field conditions in forest soilsremain only poorly understood. The goal of this project is to measure the concentrations andfluxes of DON, NH+4 , NO−3 and DOC in bulk precipitation, throughfall, forest floor leachatesand soil solutions of a deciduous stand in the Steigerwald region (northern Bavaria, Germany).The DOC and DON concentrations and fluxes were highest in leachates originating from theOa layer of the forest floor (73 mg C L−1, 2.3mg N L−1 and about 200–350 kg C, 8–10 kg Nha−1 yr−1). They were observed to be highly variable over time and decreased in the mineraltopsoil (17 mg C L−1, 0.6mgN L−1 and about 50–90 kg C, 2.0 to 2.4 kg N ha−1 yr−1). Theannual variability of DOC and DON concentrations and subsequential DOC/DON ratios wassubstantial in all solutions. The DOC and DON concentrations in throughfall were positivelycorrelated with temperature. The DOC and DON concentrations did not show seasonalityin the forest floor and mineral soil. Concentrations were not related to litterfall dynamicsbut did correspond in part to the input of DOC and DON from throughfall. The throughfallcontribution to the overall element fluxes was higher for DON than for DOC. Concentrationsand fluxes of DON were significantly correlated to DOC in throughfall and the Oi layer.However, the correlation was weak in Oa leachates. In addition, seasonal and annual variationof DOC/DON ratios indicated different mechanisms and release rates from the forest floor forboth components. The concentrations of DOC and DON in forest floor leachates were in mostcases dependent neither on the pH value or ionic strength of the solution, nor on the water fluxor temperature changes. As a consequence, the DOC and DON fluxes from the forest floorinto the mineral soil were largely dependent on the water flux if annual and biweekly timescales are considered.