I wonder what affect 30+ years of "free tree" programs that various states and environmental clubs run for arbor day and such has had. Growing up in the midwest/great plains, ever year in elementary school we were given trees to take home and plant for arbor day. Little sticks, maybe a foot long with a small handful of roots, wrapped in damp paper towels to survive the trip home.

Someone says "oh, white oaks grow alright across the entire state, and their acorns are a good food source for the local wildlife" and they send out a few thousand of them for arbor day via elementary schools.

Some of them even survive. 30+ years later, those trees have dropped millions of acorns, most of which feed squirrels and deer or rot away, but some turn into trees.

Rinse and repeat every year. Seems like you could, over the course of nearly 40 years, unintentionally shift the population of a tree species.