Analysis of land-cover transitions based on 17th and 18th century cadastral maps and aerial photographs

This paper explores the possibility of using non-geometric cadastral maps f rom the 17th and 18th century together with aerial photographs from 1945 an d 1981 to analyse land-cover change in south-east Sweden. Habitats rich in plant species in the European rural landscape seem to be correlated with a long continuity of management. Accurate spatial data from historical data s ources are fundamental to understand patterns of vegetation and biodiversit y in the present-day landscape. However, traditional methods for rectificat ion of non-geometric maps using corresponding points from orthophotos or mo dern maps are not satisfying, as internal inaccuracies will remain in the m aps. This study presents a method to rectify the maps by local warping, the reby eliminating geometrical irregularities. Further, the land-cover change s were calculated and presented as transition matrices. The extent of arabl e fields and grasslands were analysed in relation to soil characteristics a nd continuity of management. The results show a dynamic relation between gr assland and arable field, albeit the overall proportions remained almost th e same between 17th and 18th centuries: 60% grassland to 32% arable field. The most substantial changes in land-cover were prior to 1945. Today there is 18% grasslands left in the study area, while 56% of the land-cover is ar able field. Approximately 8% of present-day land-cover is semi-natural gras sland 300 years of age or more. Compared to 300 years ago there is only 1% grassland left on peat and 2% on clay. In contrast, grassland covers associ ated with bare bedrock have been fairly stable in size. All semi-natural gr asslands with a long continuity of management were situated on shallow soil s, less than 50 cm depth. The major conclusions from this study are that (i ) correctly rectified, old maps are very useful to address questions of lan d-cover changes in historical time, (ii) general trends in land use over 30 0 years in this hemi-boreal landscape seem to underestimate the full dynami cs of land use change, and (iii) only a small proportion of the semi-natura l grassland area had a 300 year continuity of management.