DECOMP – a semi-mechanistic model of litter decomposition

The decomposition of organic matter in a forest ecosystem is simulated by DECOMP, a process-based, semi-mechanistic model built on system dynamic principles. The model divides a litter into four different substrate quality classes with different decomposition rates which are differently influenced by temperature, soil moisture content, pH and aluminum concentration in the soil solution. The model is presented with its core equations and parameter values, but also presented from a system dynamics perspective in its context as a cornerstone in a forest–soil–atmosphere model. DECOMP is aimed at simulating long-term dynamics of decomposition over several forest management rotations, and to function in concert with other model components used in forest modeling. The model is evaluated against empirical data and shows good resemblance when simulating decomposition of Scots pine needle litter with data from a four-year litter bag field experiment.