The link below shows that roughly a few decades ago the percentage of forest area in the world was just shy of 32% and recently it is down about 1%
https://data.worldbank.org/indicator/AG.LND.FRST.ZSWith 70% of the world ocean that means that about 9% of the world is forested and is now down to about 8.3-8.5%. That is millions of acres for sure but not a huge decrease and many acres of the land surface that are farmed never was forested in recent times. So regaining forest land to off set issues is a slow and very long term process. Livestock agriculture has its own cycle of using and returning nutrients back into the system. Sure there are holes or weak spots in that process but that is what research and study is all about to help change those weaknesses. There are also holes in a total plant cycle as well when we draw off nutrients. One of the big concerns about nutrient cycles is that many commodities, nutrients, food, feed, fiber etc. are transported from regions of production to regions of usage and many are then disposed of in higher concentrations near the usage centers instead of the production centers and that can have significant impact on how the natural process works or functions.
in the USA with 9 million dairy cows we produce about 2,600 lbs. of dried milk equivalent from each cow. The cow weighs 1300 lbs. so we get 2lbs. of milk equivalent per lbs. of cow. The cow eats 7 tons of dry feed per year to produce 1.3 tons of human and animal feed. Over 60% of the dry matter, maybe 75% of the dry matter cows eat is good feed but not good food for humans in the state we can use. Thus cows are pretty good converters of non human food to human food, plus we get a calf every 12-15 months and about 53% of the dry feed is returned to the production site for nutrient usage.
Both sides seem to have very, simple and tightly held views on how to solve very, very complex systems that are more likely to be herded and managed within a very grey area of the world's life cycles. There are other forms of livestock even more efficient than dairy cows in converting feed to human food , but most of those have rations and diets that are based on foods humans can utilize.
Bryce