Much of that "marginal land" originally had animals grazing on it anyway. We have barely more cows in this country now than buffalo at their peak. "Re-wilding" land would just mean we have animals grazing at that we don't eat.
We are currently consuming upto three times as many cows each year as there were wild buffalos.
https://www.sciencealert.com/the-current-mass-extinction-is-...
- Cows (cattle): In 2021, the United States had approximately 94.4 million head of cattle, including those raised for beef and dairy production.
- Beef: In 2021, the United States imported approximately 3.1 billion pounds of beef and veal, that's apx. 6 mil. cows.
- Pigs (hogs): In 2020, the United States produced around 129 million hogs.
- Pork: In 2021, the United States imported approximately 1.0 billion pounds of pork.
- Chickens (broilers): In 2020, the United States produced about 9.1 billion broiler chickens for meat.
- Poultry: In 2021, the United States imported around 913 million pounds of poultry meat, including broiler meat and turkey meat.
- Turkeys: In 2020, the United States produced approximately 229 million turkeys.
Fish, shellfish, ducks, sheep, goats, or dairy products not included.
Source: USDA National Agricultural Statistics Service