Skip to main content
Author(s):
Edwin R. Sedell, Robert E. Gresswell, Thomas E. McMahon
Year Published:

Cataloging Information

Topic(s):
Fire Effects
Ecological - Second Order
Aquatic Life
Water
Fire & Wildlife
Fish
Post-fire Management
Post-fire Rehabilitation
Erosion Control

NRFSN number: 20530
FRAMES RCS number: 12635
Record updated:

Habitat fragmentation and degradation and invasion of nonnative species have restricted the distribution of native trout. Many trout populations are limited to headwater streams where negative effects of predicted climate change, including reduced stream flow and increased risk of catastrophic fires, may further jeopardize their persistence. Headwater streams in steep terrain are especially susceptible to disturbance associated with postfire debris flows, which have led to local extirpation of trout populations in some systems. We conducted a reach-scale spatial analysis of debris-flow risk among 11 high-elevation watersheds of the Colorado Rocky Mountains occupied by isolated populations of Colorado River Cutthroat Trout (Oncorhynchus clarkii pleuriticus). Stream reaches at high risk of disturbance by postfire debris flow were identified with the aid of a qualitative model based on 4 primary initiating and transport factors (hillslope gradient, flow accumulation pathways, channel gradient, and valley confinement). This model was coupled with a spatially continuous survey of trout distributions in these stream networks to assess the predicted extent of trout population disturbances related to debris flows. In the study systems, debris-flow potential was highest in the lower and middle reaches of most watersheds. Colorado River Cutthroat Trout occurred in areas of high postfire debris-flow risk, but they were never restricted to those areas. Postfire debris flows could extirpate trout from local reaches in these watersheds, but trout populations occupy refugia that should allow recolonization of interconnected, downstream reaches. Specific results of our study may not be universally applicable, but our risk assessment approach can be applied to assess postfire debris-flow risk for stream reaches in other watersheds.

Citation

Sedell, Edwin R.; Gresswell, Robert E.; McMahon, Thomas E. 2015. Predicting spatial distribution of postfire debris flows and potential consequences for native trout in headwater streams. Freshwater Science 34(4):1558-1570. https://doi.org/10.1086/684094

Access this Document

Treesearch

publication access with no paywall

Check to see if this document is available for free in the USDA Forest Service Treesearch collection of publications. The collection includes peer reviewed publications in scientific journals, books, conference proceedings, and reports produced by Forest Service employees, as well as science synthesis publications and other products from Forest Service Research Stations.