Given the long growth cycles of trees, it took nearly a century for the fact that the forests were dying to become clear. Or perhaps I should say, "clear to the people in charge". Who knows what the plants and the animals and the people who relied on the forest knew?
This is a recurrent problem with abstraction. Because it is inherently more visible than the contextual, and because it is more likely to be wielded by those in power, it can be hard to alter.