Levin, G., Blemmer, M., Gyldenkærne, S., Johannsen, V.K., Caspersen, O.H., Petersen, H.S., Nyed, P.K., Becker, T., Bruun, H.G., Fuglsang, M., Münier, B., Bastrup-Birk, A. & Nord-Larsen, T. 2014. Estimating land use/land cover changes in Denmark from 1990 – 2012. Technical documentation for the assessment of land use/land cover changes for estimation of carbon dioxide fixation in soil. Aarhus University, DCE – Danish Centre for Environment and Energy, 34 pp. Technical Report from DCE – Danish Centre for Environment and Energy No. 38 http://dce2.au.dk/pub/TR38.pdf
According to the article 3.4 of the Kyoto Protocol, Denmark is obliged to document sequestration and emission of carbon dioxide from land use and land cover and changes in these. For this purpose, methods were developed aiming at estimating amounts and changes in land use and land cover for Denmark for since 1990, which is the base year for the Kyoto Protocol. According to the IPCC guidelines, estimation of land use and land cover must cover following land use and land cover categories: Settlement, cropland, grassland, wetland, which is fully water covered, wetland which is partly water covered, forest and other land. Except for the estimation of forest, which is partly based on analyses of satellite images, estimation of land use and land cover categories and changes in these is based on existing categorical (i.e. pre-classified) geographical information. This information includes topographical maps, agricultural registers and field parcel maps, data from nature and habitat monitoring, cadastral maps and building specific information. After pre-processing, such as removal of geometrical errors, all input data are converted into raster layers with a cell size of 25x25 meters and combined into one land use/land cover map for 2011. Since input data often spatially overlap, their combination into one map is based on an evaluation of the geometric precision of each layer. The estimation of changes in land use and land cover is elaborated for the period from 1990 to 2005, from 2005 to 2011 and from 2011 to 2012. For specific land use and land cover categories (e.g. wetlands) availability of historical spatially explicit information is limited. As a consequence, estimations of change in land use and land cover from 1990 up to 2011 does to some extent involve assumption based on expert knowledge. Due to a significant increase in the availability of detailed spatially specific categorical information, estimations of annual changes in land use and land cover from 2011 and onwards are based on identification of changes in land use and land cover based spatial on overlays with updated input layers.