Investigating land area categories in large-scale historical topographic maps in relation to analysing land use and land cover changes

Analysis of historical land use and land cover change (LULCC) of pre-1950s landscapes primarily relies on cartographic documents as the source of spatially explicit information. Methodologically, most historical LULCC studies utilizing historical cartographic documents re-port on the geometrical precision and correctness of georeferencing and vectorization. How-ever, often less attention is devoted to careful interpretation of land area categories. Thus, in-formation in historical maps is taken for granted or seen as self-explanatory. This paper
presents an analysis of land area categories in Danish historical large-scale topographic maps from the second half of the 19th century in relation to a recent research project focused on the development of automated methods for vectorization of historical maps. The analysis reveals that the classification of land area categories is complex and that categories in the leg-end cannot necessarily stand direct comparison to modern LULC categories. Despite a similar appearance (i.e. sharing the same name as categories in current official geo-data), the categorization of land in the maps discussed here originally rested on a military oriented assessment of landscape trafficability. This result implies that thorough analysis of categories in historical maps is needed if data are to be used for LULCC studies. Thorough historical analysis of the development of the mapping and representational practices of land area categories in historical maps can reveal both a more consistent understanding of the relationship between map categories and the historical LULC, but it can also assist the development of automated methods for extracting vector data.