LODGEPOLE PINEIf you watched the Yellowstone fires in 1988, you’ve seen lodgepole pine in action. This is a tree that is built to burn. It grows in dense thickets at high elevations where the climate is usually moist and cool. But when drought and high winds come together, a mountainside can burn in a day. Lodgepole burns hot and fast, typically every 100 to 200 years. Fire opens the tree’s pitchy "serotinous" cones, which release their seeds, starting the process over again.
When it comes to surviving ground fires, this species could be called the "asbestos pine." The outer layer of its thick bark actually springs off the tree when ignited, carrying the flame yards away. Its roots run deep so they seldom burn out, while exceptionally long needles reflect heat away from large, moist buds. The ponderosa isn’t immune to crown fires, however, and it is at a decided disadvantage after such a fire burns through. Its heavy seeds seldom disperse farther than 100 yards, and since it doesn’t grow well in shade, the ponderosa is squeezed out if periodic ground fires don’t kill off other species as the forest regenerates.
Aspen trees hide their fire protection underground. Each tree is actually a clone growing from the same root system as those around it. When fire levels a stand of aspen, the roots generate more stems that can quickly outgrow any competitor. But aspen won’t grow in shade, and the new stems grow only if ground fire weeds out upstart coniferous trees. As a result of fire suppression, aspen numbers have decreased dramatically across the West.
Like aspen, whitebark pine colonizes burned areas, but where aspen springs back from the ground, the whitebark sends its seeds to the sky. Found on high mountaintops and ridges, this tree grows its cones upside down, so the seeds never drop directly to the ground. That would be useless, since the tree won’t grow in shade. Instead, the bird called Clark’s nutcracker collects them, caching them in recently burned areas. When the bird returns to snack, it always overlooks a few seeds, which end up germinating.