Resource Purpose |
We examined relations between cumulative levels of forest harvesting and density of road networks on the occurrence and abundance of bull trout (Salvelinus confluentus) in the Kakwa River Basin, Alberta. Logistic regression models showed that bull trout occurrence was positively related to stream wetted width but negatively related to percent fines, percent cobbles, reach slope, and the cumulative area of the subbasin harvested and road density. Results from zero-inflated Poisson regression models typically showed that bull trout abundance was positively related to elevation and negatively related to stream width, percent fines, percent cobble, slope, and levels of forest harvesting. Using the negative relation between bull trout occurrence and percentage of subbasins harvested derived from the most parsimonious logistic regression model, we forecasted that forest harvesting over the next 20 years is projected to result in the local extirpation of bull trout from 24% to 43% of stream reaches that currently support bull trout in the Kakwa River Basin. |