That would depend much more on cattle and lawnmowers than on fires. But it does not matter, because we don't need to wait for the natural spreading of the seeds.
We can plant any tree that we need, were we need it. And we, for sure, will need a lot in the near future.
After all, we put any road that we need where we need it. It was not an obstacle for the last 200 years, so all is needed is the political will to do the same with forests.
Well, there used to be 6 trillion trees on earth and today there are only 3 trillion left. Planting 3 trillion trees manually is certainly a lot more work then allowing them to reproduce exponentially.
