except the climate didn't change. If it had, then adding trees wouldn't have done what you wrote. In fact, I'd say the tree itself is the most important element here. not man.
The trees cut themselves down? ... with chainsaws? ... okay, boomer ... whatever ...
trees fall all the time when rotten, they become diseased by bugs and insects. Shit lightning can cause fires, has nothing to with humans. are you saying there was no underbrush? Nothing else green? dude if planting a tree restored some weather, ok I can deal with that, but climate? nope. plant a tree in a desert and let's see what happens.
I'm well aware of forest ecology ... where I live was nothing but forest before humans arrived ... 5,000 square miles of trees don't all fall down at the same time ... nor does fire plough the ground every year ... underbrush? ... no, generally farmers don't let the underbrush to grow in their fields ... why are you even asking? ...
Look up "transpiration" ... now compare, if you will, a lush tropical forest to a pasture full of cattle ... which has the most leaf surface area? ...
Yes, this effects weather ... and it effects the averages of this weather ... that's what climate is, average weather ... maybe you weren't aware of the terrible famine in that area 50 years ago ...