Wow, that is amazing. In most cases there isn't too much you need to do to protect these native trees.  One issue is encroachment of conifers, especially Douglas-fir.  The Doug fir trees can grow up thru the canopy and shade out the oaks.  So if there are conifers seeding in under and close to the tree, you might thin them out.

Avoid wounding the tree (especially roots) or compacting soil under the tree.  

Sounds like a really nice tree.