Title
Effects of Road Decomissioning on Stream Habitat Characteristics in Flathead National Forest, Montana
Abstract
The Flathead National Forest in Montana has decommissioned more than 300 miles of roads due to a 1994 lawsuit mandating grizzly bear habitat security. Presumably, this decommissioning also benefits the threatened bull trout (Salvelinus confluentus). Previous research demonstrates negative impacts of roads on stream characteristics important for bull trout; however, it is unknown if road decommissioning reverses these impacts. Our goal was to address two questions: First, is there a relationship between substrate composition (percent of fine sediment) and road density? Second, does road decommissioning have measurable effects on stream habitat? We sampled 12 streams with three different watershed types (1) wilderness, (2) roads in use, (3) decommissioned roads. In 2004, we performed habitat surveys, Wolman pebble counts, visual embeddedness estimates, substrate coring, and macroinvertebrate sampling.
There was high variability across streams regardless of treatment. Within our study area, there was a significant positive correlation between percent of sediment less than 6.3 mm and total road density (all roads – in use, decommissioned, and gated). In comparing our three treatment groups, we found the road-in-use group had the highest percentage of sediment < 6.3 mm while the unroaded and decommissioned groups were similar, but these ranked differences were not statistically significant. There was no difference in our decommissioned stream group from our unroaded stream group, implying that decommissioning is likely improving stream habitat in this area of the Flathead National Forest.
Start Date
1-4-2005 1:00 PM
End Date
1-4-2005 3:00 PM
Document Type
Poster
Effects of Road Decomissioning on Stream Habitat Characteristics in Flathead National Forest, Montana
The Flathead National Forest in Montana has decommissioned more than 300 miles of roads due to a 1994 lawsuit mandating grizzly bear habitat security. Presumably, this decommissioning also benefits the threatened bull trout (Salvelinus confluentus). Previous research demonstrates negative impacts of roads on stream characteristics important for bull trout; however, it is unknown if road decommissioning reverses these impacts. Our goal was to address two questions: First, is there a relationship between substrate composition (percent of fine sediment) and road density? Second, does road decommissioning have measurable effects on stream habitat? We sampled 12 streams with three different watershed types (1) wilderness, (2) roads in use, (3) decommissioned roads. In 2004, we performed habitat surveys, Wolman pebble counts, visual embeddedness estimates, substrate coring, and macroinvertebrate sampling.
There was high variability across streams regardless of treatment. Within our study area, there was a significant positive correlation between percent of sediment less than 6.3 mm and total road density (all roads – in use, decommissioned, and gated). In comparing our three treatment groups, we found the road-in-use group had the highest percentage of sediment < 6.3 mm while the unroaded and decommissioned groups were similar, but these ranked differences were not statistically significant. There was no difference in our decommissioned stream group from our unroaded stream group, implying that decommissioning is likely improving stream habitat in this area of the Flathead National Forest.