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Depletion and recovery of the pools of dissolved organic carbon and nitrogen from different forest floors

Mi-Hee Lee1, Ji-Hyung Park2, Stefan Peiffer3, Egbert Matzner1
1 Department of Soil Ecology, University of Bayreuth, BayCEER, Germany
2 Department of Environmental Science and Engineering, Ewha Womans University, Republic of Korea
3 Department of Hydrology, University of Bayreuth, Germany

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The release of DOC and DON from soil organic matter is a complicated process driven by biological and physicochemical processes. Heavy precipitation events might deplete the pool of potential DOC and DON, raising the question of its recovery. We tested the following hypotheses, 1) Recovery time of the DOC and DON pools is dependent on microbial activity and hence is shorter at high temperature and high substrate quality. 2) Large DOC leaching reduces CO2 production in the forest floor. Soil samples were extracted for 2 hours in an equilibrium extraction with artificial throughfall (pH4.0) at two ratios of soil to solution and incubated after the initial extraction for 14 days at 5 and 15 oC.  

the amount of DOC released being generally higher in the large soil to solution ratio and the release from beech samples always exceeded spruce. Recovery rates were larger in beech than spruce and in both stands larger at 15oC than 5 oC. The initial extraction of DOC had no effect on the cumulative CO2 production, the latter was three to ten times the DOC release

Our data suggest that the recovery of DOC pools in forest floors following leaching by heavy precipitation events is rather fast. If the laboratory conditions are extrapolated to field scale by soil stocks in the forest floor, the recovery rate was higher in Oa layer (12 kg DOC ha-1 d-1 for beech and 27 kg DOC ha-1 d-1 for spruce) than in Oi and Oe (0.6 to 3.7 kg DOC ha-1 d-1 for both stands). Recovery rates at the field scale were larger in spruce than in beech.

last modified 2014-09-30