Impact of the spatial resolution of soils data on climate reporting for organic soils using the example of Germany

SUMMARY As a result of the climate conferences in Durban (2011) and Doha (2012), voluntary accounting for greenhouse gas emissions from organic soils is now possible in national climate reporting. The quality of the data describing the spatial extent of organic soils and their relevant soil properties thus becomes particularly important. For climate reporting issues, maps for organic soils at different scales and levels of detail are used. In Germany, for example, the soil map at scale 1:1,000,000 is the basis for the emission inventory (NIR 2013). In contrast, the national inventory report of The Netherlands is based on a soil map at scale 1:50,000 (Coenen et al. 2013). This leads to questions about the optimal level of detail or scale for climate reporting. Datasets with scales ranging from 1:25,000 up to 1:1,000,000 were used to derive the spatial distribution of organic soils in two characteristic areas of the temperate zone, one in northern and one in southern Germany. Comparison of the results shows large differences in both areal and spatial accuracy, depending on the origin and quality of the data as well as on scale and landscape characteristics. In southern Germany, for example, only 50 % of the organic soils derived from smaller-scale maps can be verified by detailed data, in contrast to more than 70 % in northern Germany. In combination with the partially poor spatial accuracy, these differences have a strong impact on the calculation of greenhouse gas emissions from organic soils, leading to errors of more than 60 %. As a result, for the temperate zone we recommend a minimum scale of 1:200,000 for maps of organic soils. However, in mountainous regions with higher geomorphic heterogeneity, more detailed data may be necessary.