The best example of the grassland community is found on the loamier soils of the higher mesas in the park that receive more precipitation. Overall, the climate here effectively favors grass and shrub growth over tree growth. The grasses and shrubs of Petrified Forest are well adapted to survive the windy conditions, limited water, and soil types that exist here. The loamy soils hold moisture well, but prevent deep percolation of water. The soils are in part responsible for badland formations.
Water tends to run off and cause erosion rather than to soak in.
With low annual rainfall amounts distributed through the summer and winter months, growth of the shallow root systems of grasses and shrubs is favored over the deeper root systems of trees. Blue Gramma is the dominant grass species, with a root system specifically adapted to effectively capture surface water. Plants of the shortgrass prairie have many other adaptations for survival. Though the heavier clay soils hold more moisture, those conditions allow for the build up of salts in the soil. Most plants cannot tolerate the concentrates of salts found in the heavier soils.