Well, American chestnut grew on upland sites with thin soil in oak-hickory forest. Many of the surviving trees are on inaccessible mountain slopes and other pla

Well, American chestnut grew on upland sites with thin soil in oak-hickory forest. Many of the surviving trees are on inaccessible mountain slopes and other places unsuitable for agriculture. After they died, the canopy space was overtaken by oak, hickory, tuliptree, and other native trees. The chestnut was so populous because it simply overwhelmed the other trees with seed production. In terms of wildlife, there is no downside: the chestnut produces a larger mast than oak/hickory, and it produces every year instead of biennially. Its nut is starchy rather than oily. Chestnuts simply produce more food for humans and wildlife than the forest can otherwise. Its loss was simply a huge loss for the ecosystem.