Document: DAV-3-65-40

Island remnant patterns of forest fires in boreal forests: Far from random.

ANDISON, D.W.*

Bandaloop Landscape-Ecosystem Services, Golden, CO 80403 ¹

Abstract:
Using natural patterns as a guide for more ecologically-sound forest management activities has become a popular model in the boreal forest region of Canada. The nature of forest fire activity makes the natural pattern strategy particularly well suited in this area. For instance, the pattern of material left over after fire in islands is an ideal model for leaving residual material in harvesting blocks. However, despite the importance of knowing these details, only two limited studies exist on island remnant in boreal Canada. We embarked on a detailed island remnant study to fill this knowledge gap. Using historical photos, we delineated and classified into survival classes the island remnants of 25 fires in the foothills of west-central Alberta. We found that island remnant patterns were far more complex than originally thought. Although the total area in islands as a percentage of the disturbance area ranged between two and 60%, the average remained a constant 12% with increasing disturbance size, contrary to other studies. On the other hand, the total number of islands increased linearly with disturbance size, with less than 5 for disturbances less than 50 hectares in size, to more than 200 for disturbances over 1,000 hectares in size. We found islands in even the smallest disturbances, also contrary to other studies. Islands less than one hectare in size accounted for over 80% of the total number of islands, at least 70% of which were at least partially disturbed. In fact, only 10-25% of the islands across all 25 fires were completely untouched by fire. Large islands were less likely to be partially disturbed. Finally, approximately 30% of the variation in island locations could be accounted for by topographic features in complex terrain, compared to only 10% of the variation in flatter areas. Where topographic features could not be used to predict island locations, we did find that the general spatial pattern of islands could be represented by a fractal relationship. In the end, we learned that there is more pattern to that which we assumed to be largely a random process. These findings have been invaluable for establishing planning and monitoring goals.

Keywords: Fire pattern, island remnants, disturbance emulation

This abstract is being presented at: 11:30 AM in session:
Oral Session #58: Landscape Ecology.