ESTIMATING FOREST CHARACTERISTICS IN SCANNED AERIAL PHOTOGRAPHS WITH RESPECT TO REQUIREMENTS FOR ECONOMIC FOREST MANAGEMENT PLANNING

The objective of fc,rest management planning is often expressed as max imum sustainable economic yield. Methods used to collect information f or forestry planning should, therefore, include variables significant for economic evaluations of management alternatives. It is important t o be able to differentiate mature stands with respect to timber volume s and species mixture. In this study, digital high-altitude aerial pho tographs are tested as a data source for planning. Circular plot data from a forest estate in northern Sweden were used as reference materia l. Global positioning system (GPS) measurements, with differential cor rection, were used to georeference the plots. Harvesting priorities we re calculated for each plot using the Forest Management Planning Packa ge. Volumes, species mixture and harvest priorities were estimated usi ng regression analysis based on textural and spectral information from aerial photographs. The results show that the dependent variables cou ld be estimated fairly well using only spectral information, e.g., R-2 = 0.44 when estimating timber volume at reference plot (10 m radius) level. Aggregated to stand level, the precision was comparable with cu stomary field survey methods (e.g., RMSE = 13.4% for timber volume).