LANDFORM EFFECTS ON FIRE BEHAVIOR AND POSTFIRE REGENERATION IN THE MIXED FORESTS OF NORTHERN JAPAN

This study was conducted to clarify the characteristics of landform ef fects on fire behavior and post-fire regeneration and to examine regio nal differences in the effects of fire within a mixed-forest area with various topographic conditions in Hokkaido, northern Japan. Fire spre ad was controlled by topographic barriers such as ridges and valleys, although this was not clear in the areas with serpentinite. Fire frequ ency was higher on windward slopes of the prevailing wind, and the siz e of the burned area varied with the underlying geology, which control led the areal extent of hillside slopes. In areas with terrace deposit s, Wakkanai Formation or serpentinized rock, burned areas were large a nd included few unburned stands. The type of vegetation that grew foll owing the fires varied with slope aspect and topographic position. Sas a grasslands often formed at wind-exposed sites. The grasslands were w ell developed in the three areas with the previously mentioned geology , where large-scale burning had occurred. Structure of the re-establis hed forest stands was also affected by landforms. Canopy height and th e maximum diameter at breast height varied with slope aspect, topograp hic position and elevation, as well as with stand age. Tree size was f ound to decrease at wind-exposed sites within high-elevation zones.