Ecological - Second Order
In 2000, wildfires burned more than 200,000 acres on the Bitterroot National Forest of Montana and nearly 1.5 million acres in the Northern and Intermountain Regions. Management activities associated with fire suppression and post-fire restoration have had the unintentional consequence of promoting invasive weeds. As part of fire suppression efforts, dozer lines were constructed in an attempt to slow or stop the fire. These dozer lines introduced spotted knapweed (Centaurea biebersteinii) into areas that were previously weed free. Spotted knapweed density decreased exponentially with distance from the road (the weed source). Two years post-fire, spotted knapweed densities had increased along the dozer line and spotted knapweed had colonized further into the forest. As part of the BAER restoration efforts, contour felling was conducted to trap sediment and slow erosion. The contour felled logs acted as seed traps for spotted knapweed. In 2001 and 2002, spotted knapweed densities at the logs were significantly higher than spotted knapweed densities above or below the logs. Knapweed at these logs can act as source populations for further weed expansion into the burned areas. The BAER plan also called for herbicide treatment of some knapweed-infested areas. While herbicide was very effective in eliminating spotted knapweed, it also significantly decreased herb richness and herb percent cover and altered the bunchgrass community.