A species driven approach examining fire impacts and habitat recovery for barren ground caribou (Rangifer tarandus groenlandicus)

Gregory J.M. Rickbeil (1), Nicholas C. Coops (1), Txomin Hermosilla (1), Mike A. Wulder (2)

1 Integrated Remote Sensing Studio, Department of Forest Resources Management, University of British Columbia: @IRSS_UBC

2 Canadian Forest Service (Pacific Forestry Centre), Natural Resources Canada

Fire regimes in Canada’s northern boreal forest are changing, affecting available habitat for barren ground caribou across their southern range. Multiple recent studies have employed successional vegetation modelling to estimate available habitat in the future given different fire regimes. Here, we present an alternative method for assessing caribou habitat recovery post-fire by examining caribou behaviour pre-fire and  post-fire  across  five  decades.  We  expect  complete  avoidance  by  caribou  immediately  post-fire, followed by recovery of travel focused behaviour then foraging behaviour. Fire disturbances were mapped using best available pixel Landsat data from 1985 to 2011, after which fire disturbances were detected using break point analysis and extended to 1955 using historical fire databases. Caribou behaviour was examined using step length and turning angle from 274 animals across five herds. Behaviour post-fire was assessed using generalized additive mixed models. Pre/post fire analysis demonstrated strong avoidance of burned locations, confirming our first hypothesis. Behavioural recovery, however, occurred much earlier and in a more complex fashion than hypothesized. Burned locations were used in spring, fall, and winter as early as three years post fire. In spring and fall, travel did recover prior to foraging; however, behaviour in winter showed little response to time since fire. Our approach allows for a more direct estimation of caribou habitat recovery post fire while considering different behaviours and seasons. Importantly, our results indicate that use occurs earlier than predicted in successional modelling, suggesting an overestimation of habitat loss when using successional models to project future caribou habitat.