I have long noticed a strange feature of my plein airs: if I go out to paint in the city or in some frequently visited place, after a while this place disappears

Sounds like you could write a creepypasta about that :)

I hope there was an actually good reason the trees were cut down (termites, rotting etc, I guess I'll vaguely accept "roots getting into pipes" as well). I kind of hate people who cut trees down because they're "in the way" or "messy".