When colonists first started arriving in the United States, all of New England was cultivated. Then Americans learned something: New England sucks (for farming, at least). The farmers moved west, and much of New England reverted to forest land. This is why you find farmyard stone walls in the middle of Vermont forests.
What if Europeans had told the Americans, "You can't just plow up all that grassland; that's an entire ecosystem you're planning to destroy!"? Americans would have been forced to keep farming the poor New England soil, getting less output from their labor, meaning they would be poorer than they otherwise would have been.
African farmers try to coax crops out of the Sahel while some of the richest soil on Earth sits under the Congo rain forest. Why does all the blame for African poverty get laid at the feet of Western governments and businesses, and none of it ends up attached to Western conservationists? We have this notion of Africa as a place "where nothing ever grows," but to the extent that is true it's true because the Africans face Western disapproval if they use their most-productive soil for crop production.