Satellite remote sensing has long been understood as a potentially efficient tool for forest management planning. In order to accelerate the integration of these two techniques, a major Nordic research project was launched in 1986. Research teams from Denmark, Finland, Norway and Sweden cooperated in the project, which was coordinated by the Swedish University of Agricultural Sciences and financially supported by The Nordic Forest Research Cooperation Committee (SNS). The results of the research project are being published as four separate articles in the Scandinavian Journal of Forest Research. In this issue, the work done at the Remote Sensing Laboratory of the Swedish University of Agricultural Sciences is reported. A Geo Information System called IRR is defined and implemented as a solution to the problem of integrating satellite remote sensing in a GIS. IRR is the Swedish abbreviation for "interactive editing of raster data". A special characteristic of the IRR is that satellite images, maps and verbal descriptions are integrated parts of the data base. Images may be visually interpreted or processed analytically. The IRR emphasizes the following concepts: the marked interactive nature and the powerful editing capabilities. In this context, editing involves everything from editing of raw data to forest management planning. The IRR is for that reason, in the first place, designed as the platform for a powerful forest management planning system and secondly, as a forest mapping system. The system is user friendly and the user interface is designed according to the "point-and-click" philosophy characteristic of Apple personal computers (the threshold of learning the system is comparable to that of a Macintosh personal computer). Although the IRR is basically a raster system, it can yet handle both raster and vector data. Raster data are therefore used where raster suits best and vector data where vectors suit best. A newly developed spatial data model makes it possible to use both vector and raster data simultaneously, without continuous data conversions. The data base of the IRR contains maps, satellite images and verbal descriptions. These data describe the state of the nature at a certain point of time. In forest management planning, these data are used together with knowledge about the forest, to plan actions in the nature in both short and long terms. Knowledge about the forest may either be simple heuristic models in the head of a user or complicated growth models within the system.
