In some cases it IS planted specifically for forage, but in terms of resources going into it, this is relatively low impact in most cases. These plants are typically either self-seeding annuals, biannuals (which often self-seed and whose seed doesn't all germinate in the same year), or perennials.

In some locations forages are just what grows naturally, and these have the lowest environmental impact.

Encroachment from hardy perennial shrubs and trees around edges is eliminated with annual mowing, and most "weeds" require bare soil to germinate, so stands of these forages CAN last as long as twenty to thirty years.

There are less than satisfactory forages in less than satisfactory places that sort of push against the ethics and skew any judgements about forages and hay in general. One such crop is Alfalfa, raised in the American southwest, irrigated with water from fossil aquifers, fertilized to promote growth, and sprayed with chemicals to ensure that it's JUST alfalfa. This is just as bad as any other cash-crop in America.

I do appreciate your sharing this. Thank you!