Caribou are very sensitive to increasing amounts of disturbance and habitat loss, as I previously said, so the biggest service to them is to actually limit disturbance over larger areas. Certainly older-growth, contiguous areas of forest are most important for them, because once those start to degrade, then the system changes to one that allows in more predators and early successional species like moose, deer and so forth, and that can then lead to unsustainable levels of predation.
That's why the habitat becomes very important, because the larger the areas you have of these older, mature forests that also produce food for these animals, the better the habitat is in the long run.