50 Years Ago, This Was a Wasteland. He Changed Everything

[Kali]

9. Cedars tend to take over when grasses are depleted.

That can happen with bad grazing management (either overgrazing, not grazing enough or usually, both at the same time), fire suppression or over use. Depends on rainfall and moisture conditions, but the old "climax community" of succession plays a role too.

Healthy perennial grasses need to be grazed or otherwise cycled or they tend to choke themselves out. Grassland ecosystems need large herbivores to function.