ANALYSIS OF HISTORIC LANDSCAPE PATTERNS WITH A GEOGRAPHICAL INFORMATION-SYSTEM - A METHODOLOGICAL OUTLINE

Various methods for storing, retrieving, and analyzing historic land use records by means of electronic data processing are evaluated. The procedures are illustrated with data from a pilot study on the Swiss Plateau which is part of a broader landscape historical monitoring program at the Swiss Federal Institute of Forest, Snow and Landscape Research. The land use matrix was derived from topographic maps, aerial photographs and other land use records and spans approximately 100 yrs with an updating cycle of 7 to 20 yrs. A special technique was developed to generate series of digital maps and to superimpose the data layers of various time steps. Each landscape element is described with time-stamped attributes to ensure access to the entire ''life history'' from any point in space or time. The proposed data model proved to be a powerful tool for routine updating of digital maps. It can be used by practitioners as well as scientists working with Geographical Information Systems (ARC/INFO or similar package). With this procedure, disturbance maps over any number of available updates can be quickly generated, allowing the user to identify zones of similar degrading or upgrading tendency. The procedures for analyzing changing landscape structures include calculation of information theoretic indices (diversity, dominance), calculation of fractals, edge analysis, as well as landscape assessment along random traverses. The latter proved to be especially powerful, where barrier/habitat frequencies were evaluated. On the basis of all parameters calculated, landscape structures on the study plot seem to be ecologically most favorable in the 1930's followed by a strong degradation in the World War II- and the post-World War II period. In contrast to many hypotheses, the landscape structures in the second half of the 19th century were structurally less favorable than between 1900 and 1930.