---The other species of trees are not vulnerable to the beetles. In several hundred years, the only mountain trees we'll have are Oaks and Firs.---
In California fire would be beneficial to redwoods as well. They need fire to expand their range.
Redwoods are primarily coastal trees, and need a LOT of water to grow. I usually see redwood groves near a free flowing river, or where there's a lot of rainfall. I don't really know how far they can expand.
We lost quite a few of the giants in the last Yosemite fire.