Using operating area size and adjacency constraints to mitigate the effects of harvesting activities on boreal caribou habitat

Sustained timber harvesting conflicts with the long-term viability of boreal caribou (Rangifer tarandus caribou) populations. The spatial arrangement of harvest blocks in the landscape could mitigate the impact of logging on caribou populations. For the forest industry, however, these measures represent constraints that reduce the annual allowable cut (AAC). Estimate the long-term impacts of spatial constraints to harvesting, applied alone or in combination, on AAC and boreal caribou populations. We divided a 30,000 km(2) region into 20 harvest block sizes varying from 50 to 1000 km(2), and modeled the implementation of spatially explicit harvest schedule plans in combination with wildfire and caribou population dynamics. We then evaluated the probability of persistence of boreal caribou populations. The probability of maintaining an AAC target declined with increasing target AAC, increasing size of operating area, and increasing adjacency constraints. In contrast, the probability of maintaining caribou populations declined with increasing AAC, decreasing size of operating areas, and decreasing adjacency constraints. An increase in operating area size from 50 to 300 km(2) produced a considerable gain in AAC for all adjacency constraints. Because adjacency constraints led only to a small increase in the probability of maintaining caribou populations, we recommend adopting less constraining landscape management actions, such as a 70-year period between two consecutive harvests in the same similar to 300-km(2) operating area.