> plant diversity peaked in the medieval era, when small farms created a patchwork of fields, pastures, and forests that supported a greater array of plants than either the closed forests that came before or the industrial farms that would follow.

That seems reasonable from a study from Europe they quoted. If farmed land, garbage left around, or brush clearing was helping certain species thrive it could mean they will struggle once farm plots and that other stuff goes away. It would be rather silly to have someone dump piles of rotting food in the woods to keep up the wild boar biodiversity that’s now declining.