Forest Type DOC/CON Dynamics and Exports
DFG-TERRECO Cluster F-04
Von 01/2014 bis 07/2015Projektleiter
: Egbert Matzner
, Stefan Peiffer
, Ji-Hyung Park
: Mi-Hee Lee
There is a lack of knowledge concerning the transport of organic matter from terrestrial to aquatic ecosystems. The transport of organic C and N from terrestrial to aquatic systems can occur in the form of DOM but also in the form of particulate organic C and N (POC, PON) of different sizes. In the case of N, transport of mineral N (NO3- and NH4+) may also add to the N loss from terrestrial systems and to the pollution of surface water. In some forest ecosystems DON was found to be the major loss of N with seepage.
As much of the DOM in aquatic systems originates from terrestrial organic matter, the transport of terrestrial C and N into aquatic environments is a significant link between these systems. The terrestrial organic matter is especially exported to the aquatic environments during high precipitation events, like during the monsoon. Also, precipitation events can change fluxes and concentration of DOC and POC by shifting preferential flow through macropores, runoff, and lateral flows in the catchment. Tree species effects on the fluxes of DOC, DON, POC and PON in runoff may result from different litter and humus quality which might influence the composition and reactivity of DOC in soil solutions and runoff. DOM from coniferous litter generally comprises more refractory, hydrophobic, and aromatic compounds, whereas DOM from broadleaf trees comprises a larger proportion of labile, hydrophilic, and low molecular weight substances. Besides the quality of litter, the amount of organic matter in the forest floor is normally larger in coniferous forests than in broadleaf forests. Under high precipitation events and near-surface runoff, this may result in higher losses of DOC, DON, POC and PON from coniferous than from broadleaf forests. In this study, we will investigate the DOM and POM concentrations and fluxes in bulk precipitation, throughfall, forest floor percolate and runoff of coniferous and broadleaf forests in the Soyang Lake Watershed during monsoon events. We will test the following hypotheses, 1) Export of DOM and POM from coniferous forested watersheds during monsoon rainfalls differs from broadleaf dominated watersheds, 2) The quality of DOM and POM in throughfall and runoff reflects the forest type, 3) Export of fine PON is the dominating form of N loading of runoff, and 4) The concentration respond to discharge and precipitation intensity during monsoon events is similar for C and N (DOC vs. DON; POC vs. PON).
Cohort 2 projects of the “Inputs to Soyang Reservoir Cluster” are designed to follow material transfer from the land surface through the river system into the Soyang Lake, but also investigate the transformation and fate within the lake. In view of global climate change and future land use, predicting the tendency of organic C and N transfers from different forest types to aquatic systems is important information with regard to decision supporting and to risk evaluation.
Key words: DON, DOC, fine POC, PON, precipitation, coniferous, broadleaf, forested watersheds