Decreasing meat consumption would dramatically decrease the amount of land amount used for crop agriculture, not increase it. 85% of the UK's landmass is grazing land and crops grown specifically as animal feed[1].

In 2010, the British livestock industry needed an area the size of Yorkshire just to produce the soy used in feed. But if global demand for meat grows as expected, the report says, soy production would need to increase by nearly 80% by 2050. [2]

From a completely theoretical standpoint, if humans were to stop consuming meat we would actually need to close 1000's of crop farms, not open them on rolling hills, even when accounting for our dietary increase in plants. I'd therefore argue that it's a shame the land has to be used for agriculture at all. Better would be to maintain them as national parks and the like.

[1]http://www.sciencedirect.com/science/article/pii/S0959378017...

[2] (PDF WARNING) https://www.wwf.org.uk/sites/default/files/2017-10/WWF_Appet...

More national parks! As a recreational hiker and walker that would be a dream. I'd go vegetarian myself if it guaranteed even 50% more parkland.

The problem as I understand it is that while cattle are often raised in such places - grazing on open grass plains which could not support other crops - they are usually transferred to feedlots later in their life, where a significant portion of the nutrients used to support them come from corn, soy, etc, which do come from croplands.

So in our current system it does appear that cattle, even if they occupy some grassland space which could not be more efficiently used, do inevitably use resources which could be more efficiently used to feed humans directly.

But of course humans have been changing that landscape for millennia to graze livestock on it - it was much more forested before we arrived, and could be again.

The demand for, and thus price of, feed crops will decrease if we largely switch from real meats to plant-based substitutes, so there will be less economic incentive to grow crops on those rolling hills, not more. They could still be used to raise livestock (we're probably not going to eliminate 100% of meat and animal products from the market), or just returned to nature.

If we got to a place where most of the cow & lamb feed comes from open range grazing we'd be in a fabulous place.

It's much the same in the Alberta plains. You'd have to dramatically alter the ecosystem to grow a variety of crops there.