ROMUL — a model of forest soil organic matter dynamics as a substantial tool for forest ecosystem modeling

This paper discusses a model of forest soil organic matter based on the concept of succession stages of soil organic matter decomposition marked by different groups of soil fauna inherent to forest soils in contrast to well-mixed agricultural soils with microbiology kinetics. This model allows the calculation of the dynamics of soil organic matter and the corresponding dynamics of nitrogen, including the evaluation of the amount of mineral nitrogen which is available for plants. The input parameters are the amount and quality of litter input, climatic data and initial amounts of soil organic matter and corresponding nitrogen. The litter may be split into different cohorts which are characterised by different ash and nitrogen contents and location on/in a soil as above-ground and below-ground litter cohorts. A specially developed simulator of soil climate is also described. A comparison was made with a previous, more restricted version of this model. The origin of the differences is discussed in detail. Examples of simulation scenarios show a wide range of possible applications for the model as a separate unit of models for forest ecosystems dynamics.