A variety of grazing animals such as sheep, goats, cows, horses, deer and other wild critters, call the San Domingo ranch land home. The San Domingo grazing land is not just grass - the topsoil is a dense web of roots. There are also legumes (such as clovers) and deep-rooting herbs ("weeds", also known as forbs). The legumes have nodules in their roots colonized by special soil bacteria (rhizobia) that "fix" nitrogen from the atmosphere into food for plants. The herbs bring up new minerals from the subsoil and replenish the topsoil.

The most important aspect of grassland is the grazing animals that eat the grass. Along with the grazing itself and their trampling effect, it is the action of the animals in fertilizing the topsoil that makes the lush growth and crop density possible.  Pasture and grazers can almost be viewed as a composite creature, the one an aspect of the other. In a sense the grazers cause the pasture: remove the animals and the land changes.