PARENT SESSION
Oral Session #7: Disturbance in Forests: Fire, wind, and other.
Presiding: G. Murray
Monday, August 5. 8:00 AM to 11:30 AM. Cochise Meeting Room, TCC.

Fire and fire suppression mediated changes in forest composition and landscape structure of the Boundary Waters Canoe Area, northern Minnesota, USA.

Scheller, Robert^*,1, Mladenoff, David¹, ¹ University of Wisconsin-Madison, Madison, WI

ABSTRACT- The Boundary Waters Canoe Area (BWCA) of northern Minnesota exemplifies how human behavior and natural disturbance determine forest composition and landscape structure at a regional scale. Historically, the BWCA was subject to stand-replacing fires with a return interval of 50-100 years and may never have reached a steady-state climax community (defined as large contiguous areas of old-growth forest). Complete fire suppression began in the early 1900s, resulting in a more demographically diverse structure. Shade tolerant species typical of old-growth forest in the region began replacing the shade intolerant species that composed the fire-generated even-aged stands. Notably, the replacement of early successional species is occurring at the scale of individual gaps, producing multi-aged stands. Newly created gaps are less likely to be filled by the currently dominant canopy species. Red pine stands are uncommon in the BWCA and are of special concern. We used LANDIS, a spatially explicit forest landscape model, to determine the long-term consequences of natural fire regimes or fire suppression on forest composition and landscape structure. Our models predict that if a natural fire regime returns, forest demographics and landscape structure will not recover in less than 100 years. Under moderate fire suppression, full restoration to earlier demographic states is unlikely. If full fire suppression continues, the forest may never recover and red pine may be lost as a locally dominant species.

KEY WORDS: fire suppression, forest landscape model, landscape structure, disturbance