Coupled simulation of regional land use change and soil carbon sequestration: A case study for the state of Hesse in Germany

The paper introduces the HILLS (Hesse Integrated Land Use Simulator) model system that implements an integrated approach to simulate the effects of land use change on biogeochemical processes on the regional scale. The model system is realized within a GIS-based modular software framework and includes a spatial two-scale hierarchy with the macro-level representing administrative units and the micro-level being defined by a 1 × 1 km grid. First application of HILLS is the assessment of soil carbon sequestration due to cropland abandonment in the federal state of Hesse, Germany. For this study the land use model LUCHesse has been newly developed and coupled to a modified version of the Century model (GIS-Century) in the HILLS context. LUCHesse regionalizes macro-level area trends of land use types to the grid level in annual time steps. The generated sequence of land use maps serves as input to GIS-Century for calculating soil carbon sequestration. The paper focuses on the conceptual and software aspects of HILLS as well as on the implementation for the Hessian study. Furthermore results of model testing and application of the integrated model to the problem in question are presented.