It may be unusable as crop fields, but grazing it often prevents it from developing into a richer ecosystem that might be able to support a greater variety of wildlife and sink more carbon dioxide.
A rather extreme example of this somewhat famously happens down in Brazil, but there's also a not completely off-the-wall hypothesis that this phenomenon also at least partially explains the Little Ice Age. IIRC, the basic goes that the American peoples relied heavily on a version pasture-based livestock agriculture, which involved limiting the growth of forests in order to ensure plenty of grassland for large bison herds. The wave of plague that killed people off after European contact meant that the pasture land was no longer being maintained, and began to revert back to forest. This, in turn, sucked so much CO2 out of the atmosphere that it altered the world climate.
I would argue that you can't point to a single source like that in ecology.
Grasslands are the way they are due to draught as well. They have dry periods, and during these they catch on fire and the whole thing burns down.
> "A grassland can become either a desert or a forest if conditions like temperature, amount of rainfall, how often fires occur and how many herbivores live in these areas change. As more and more trees grow in a grassland, it is sometimes called a savanna."
It may be unusable as crop fields, but grazing it often prevents it from developing into a richer ecosystem that might be able to support a greater variety of wildlife and sink more carbon dioxide.
A rather extreme example of this somewhat famously happens down in Brazil, but there's also a not completely off-the-wall hypothesis that this phenomenon also at least partially explains the Little Ice Age. IIRC, the basic goes that the American peoples relied heavily on a version pasture-based livestock agriculture, which involved limiting the growth of forests in order to ensure plenty of grassland for large bison herds. The wave of plague that killed people off after European contact meant that the pasture land was no longer being maintained, and began to revert back to forest. This, in turn, sucked so much CO2 out of the atmosphere that it altered the world climate.