A carbon balance model for organic layers of acid forest soils

Organic layers of acid forest soils are highly dynamic carbon reservoirs. D uring forest succession the, stored amount of organic carbon (OC) changes d rastically. Because of feedback between OC storage in organic layers and in mineral soils and other compartments of the environment (plant, atmosphere , and groundwater), there is a strong need for applicable carbon balance mo dels, particularly for organic layers. In this paper a simplified model for the carbon balance of organic layers ( CABOLA model) of acid forest soils is presented. The model considers two ho rizons, the L and O horizon. Decomposition and transport processes are desc ribed by first order differential equations. C input into the organic layer is due to litter fall onto the L horizon. The governing equations are solv ed by integration. To demonstrate the model's capability of simulating the OC dynamics of orga nic layers, data on OC storage in organic layers of acid sandy forest soils with deep groundwater tables (Podzols) under pine stands were used. Togeth er with literature data and some assumptions, these data were used for a fi rst, rough estimation of the model parameters. Model calculations confirm t hat the CABOLA model is in principle able to simulate the dynamics of OC st orage in organic layers during forest succession. Nevertheless, intensive r esearch efforts will be necessary to independently parameterize the model f or broad applications.