COMPARISON OF SATELLITE IMAGERY AND INFRARED AERIAL-PHOTOGRAPHY AS VEGETATION MAPPING METHODS IN AN ARCTIC STUDY AREA - JAMESON-LAND, EAST GREENLAND

The two methods suited for mapping the vegetation of remote inaccessib le terrain were compared in terms of their ability to reproduce and di stinguish predefined vegetation classes, the appropriateness of their different spatial resolutions to the same end, and their cost-effectiv eness. The study was carried out in Jameson Land, East Greenland (70-d egrees 30'N to 72-degrees-N). The vegetation had previously been class ified and mapped by the use of false colour infrared aerial photos in the period 1982-86 The resultant vegetation maps had been drawn on aer ial photo overlays at a scale of 1:25,000. SPOT data from 8 September 1986 and Landsat TM data from 10 August 1987 were used. A supervised c lassification of the combined satellite data was made using a maximum likelihood algorithm. A vegetation map was produced which accurately p lotted 9 of the dominant vegetation classes and 4 non-vegetation class es. The two mapping methods were then compared. The satellite-based me thod was found to be inadequate for the mapping of vegetation classes which occur in very small vegetation patches. The photo-based mapping had better potential to map these vegetation classes because aerial ph otos have a higher spatial resolution than the satellite data. Small p atches of herb slopes were selectively pinpointed in the photo-based m apping process. As the dominant vegetation types were, however, plotte d in less detail, the photo-based mapping generally produced larger ve getation units with a more homogeneous and less complex texture than t he satellite-based method. Of the two methods, the satellite-based met hod was by far the more cost-effective. Satellite data were less expen sive to obtain and process than aerial photos and time-consuming inter pretation was eliminated. Both methods require detailed ground-truthin g, but the satellite-based method requires less so due to the objectiv e classification procedure. Overall, the satellite-based method seems advantageous for vegetation mapping in large remote areas. However, th e satellite data still lacks the resolution to map all the important c over classes of the fine-scaled arctic tundra vegetation mosaic. There fore purpose-specific adaptation of cover classes and manual augmentat ion may be necessary.