Estimate Carbon in Organic Soils –Sequestration and Emissions (ECOSSE):
Whilst a few models have been developed to describe deep peat formation and turnover (for example Clymo 1992), until recently, none had been developed that were suitable for examining the impacts of land use and climate change on the types of thin organo-mineral soils that are often subject to land use change (Smith et al. 2007). These organo-mineral soils have a thin surface organic horizon <50 cm thick. The main aim of the ECOSSE model is to simulate the impacts of land use and climate change on GHG emissions from these types of soils, as well as mineral and peat soils. The model is a) driven by commonly available meteorological, land use and soil data, b) able to predict the impacts of land-use change and climate change on C and N stores in organic and mineral soils, and c) able to function at national scale as well as field scale, so allowing results to be used to directly inform policy decisions.
The ECOSSE was developed from concepts originally derived for mineral soils in the RothC (Jenkinson & Rayner 1977, Jenkinson et al. 1987, Coleman & Jenkinson 1996) and SUNDIAL (Bradbury et al. 1993, Smith et al. 1996a) models. Following these established models, ECOSSE uses a pool type approach, describing soil organic matter (SOM) as pools of inert organic matter (IOM), humus (HUM), biomass (BIO), resistant plant material (RPM) and decomposable plant material (DPM). All of the major processes of C and N turnover in the soil are included in the model, but each of the processes is simulated using only simple equations driven by readily available input variables, allowing the model to be applied at both field and national scales, without a great loss of accuracy. ECOSSE differs from RothC and SUNDIAL in the addition of descriptions of a number of processes and impacts that are not crucial in the mineral arable soils that these models were originally developed for. More importantly, ECOSSE differs from RothC and SUNDIAL in the way that it makes full use of the limited information that is available to run models at national scale. In particular, measurements of soil C are used to interpolate the activity of the SOM and the plant inputs needed to achieve those measurements. If data are available describing soil water, plant inputs, nutrient applications and timing of management operations, these can be used to drive the model and so better apportion the factors determining the interpolated activity of the SOM. However, if any of this information is missing, the model can still provide adequate simulations of SOM turnover, although the impact of changes in conditions will be estimated with less accuracy due to the reduced detail of the inputs. A complete and detailed description of the structure and formulation of the ECOSSE model is given in Smith et al. (2010).ECOSSE User Manual