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In British Columbia, Canada, the largest mountain pine beetle outbreak on record has resulted in changes to fuel complexes that may alter fire regimes. The goal of this study is to analyze the relative importance of mountain pine beetle infestations as a determinant of forest fire ignition density in British Columbia. Fire ignitions data for the years 2000 to 2007 were modelled with covariates (weather, topography, ignition source, and the nature of the mountain pine beetle infestation) in 1km by 1km cells in the Montane Cordillera ecozone. Kernel density estimation was conducted for each fire season to illustrate broad scale trends in fire occurrence and regression trees were used to analyze the relative importance of each covariate. Results indicate precipitation, temperature, and Seasonal Severity Rating were the most influential determinants of fire ignition densities. While mountain pine beetle covariates were of lesser importance, moderate stand level tree mortality was more important for predicting the highest modelled fire ignition density values than high or extreme level mountain pine beetle mortality. Elevated fire ignition density was also associated with forests attacked by mountain pine beetle both one and six years previous, while other years were less important predictors. [ABSTRACT FROM AUTHOR]

Non-invasive measures for assessing long-term stress in free ranging mammals are an increasingly important approach for understanding physiological responses to landscape conditions. Using a spatially and temporally expansive dataset of hair cortisol concentrations (HCC) generated from a threatened grizzly bear (Ursus arctos) population in Alberta, Canada, we quantified how variables representing habitat conditions and anthropogenic disturbance impact long-term stress in grizzly bears. We characterized spatial variability in male and female HCC point data using kernel density estimation and quantified variable influence on spatial patterns of male and female HCC stress surfaces using random forests. Separate models were developed for regions inside and outside of parks and protected areas to account for substantial differences in anthropogenic activity and disturbance within the study area. Variance explained in the random forest models ranged from 55.34% to 74.96% for males and 58.15% to 68.46% for females. Predicted HCC levels were higher for females compared to males. Generally, high spatially continuous female HCC levels were associated with parks and protected areas while low-to-moderate levels were associated with increased anthropogenic disturbance. In contrast, male HCC levels were low in parks and protected areas and low-to-moderate in areas with increased anthropogenic disturbance. Spatial variability in gender-specific HCC levels reveal that the type and intensity of external stressors are not uniform across the landscape and that male and female grizzly bears may be exposed to, or perceive, potential stressors differently. We suggest observed spatial patterns of long-term stress may be the result of the availability and distribution of foods related to disturbance features, potential sexual segregation in available habitat selection, and may not be influenced by sources of mortality which represent acute traumas. In this wildlife system and others, conservation and management efforts can benefit by understanding spatial- and gender-based stress responses to landscape conditions. [ABSTRACT FROM AUTHOR]