Thanks in part to roughly 100 years of fire suppression on the Great Plains, this drought-tolerant native tree [eastern red cedar] — once primarily confined to river bottoms and rocky outcrops — has crept from the gullies to the grasslands, from the humid East to the arid West from Texas to South Dakota, and is now dismantling what little remains of one of the most endangered ecosystems in the world.
In much of western North America the pre-Columbian fire regime was frequent low-intensity fires. This let some types of forests grow in some places, but not have the super-intense-kill-everything fires, and preserved the plains as grasslands.