Healthy Ecosystem Whitebark pine thrives in the subalpine regions of the western U.S. and Canada. The fire-tolerant pine produces an abundance of nuts, which are eaten and stashed by Clark's nutcrackers, right. Nutcrackers bury caches of nuts in loose soil on the mountainside. Bears travel to the high country in the summer in search of nutcracker stashes. Intermittent fires scorch back competing subalpine fir trees.
Fires also loosen soil, which is ideal for nutcracker caches.
Nut stores, which are forgotten and undiscovered, sprout into clusters of young pine trees. An introduced fungus, white pine blister rust, has weakened many pines to the extent that they can no longer exude enough sap to defend themselves against mountain pine beetles. Unchecked, beetle larvae can girdle a tree. With fewer seeds available, the nutcrackers eat more of what they harvest, reducing the potential for seed germination. Suppression of fire allows subalpine fir trees to overwhelm whitebark pine stands, crowding out slow-growing pine seedlings.