It's hard to pick a favorite tree in Yosemite. I'm partial to sugar pines and sequoias are amazing of course. Nobody, or almost nobody, travels to Yosemite to see the knobcone pines. It's a short, scraggly tree. No big deal. But it has perhaps the most interesting survival strategy of any tree in the park. A sugar pine may grow to 80' before it produces its first cones, but the knobcone pine begins putting out cones at a young age. But here's the interesting part: it does not spread those seeds. Most closed-cone pines like the sugar pine just need a bit of bright sun to get the resins running, dry out the cone, open up and spread its seed. The knobcone pine needs temperatures above 350 degrees F just to spread its seed. That's hot enough to bake cookies.

If a fire doesn't come along, the knobcone pine cones will just sit on the tree waiting, waiting, waiting. The past century of human fire suppression has, therefore, been bad for the knobcone pine. The amazing thing is that very commonly a fire is only hot enough close to the ground. It will kill the tree, but the upper cones won't even get hot enough to open. You can often see perfectly green cones at the top of a dead tree still waiting for a hotter fire. Eventually the tree will die and fall over, the but cones will remain green and viable for years until a ground fire comes along.

Most pines as they mature drop their lower branches. This prevents fire from traveling up the tree and crowing. Knobcone structure, though, actually promotes crowning, thus providing the heat necessary to vaporize the cone resins. Thus, unlike most pines, a "normal" fire in a knobcone forest is a stand replacement fire.

One peculiarity of the knobcone pine is that the some of the cones cluster right around the trunk. As the tree grows, if no fire ever comes along, the trunk will eventually envelope they cones until they are entirely encased in wood. Scientists have opened this cones and the seeds are almost as viable as fresh seeds from a good cone out on the branch.

After a fire sweeps through, the seed release and the first ones will germinate with the winter rains. However, some seeds will stay in the cone and disperse over several years. So on the chance a second fire comes through in short order, the knobcone pine doesn't blow its whole load that first season after a fire. The knobcone needs soil with a high pH and high levels of phosphorus and nitrogen and depends on fire to provide those conditions and since few other species like similar conditions, the competition is much reduced, letting the knobcone be an early pioneer in fire-cleared areas.

Finally, knobcone pines hate shade. So once again, they are dependent on fire to keep their habitat open. If there's no fire and taller trees grow up around them, the knobcone pine can't survive.

See also the forest service page.