Distribution and Control of Several Woody Plants in Texas and Oklahoma

Abstract

DURING the period that civilized man has held dominion over the Southwest, dwarf forests of invading shrubs and small trees have insidiously taken possession of millions of acres of the remaining uncultivated grassland. Acreage of mesquite alone in Texas and Oklahoma is greater than the area of the state of Wyoming. Many have been deceived into believing that trees and brush moved in like a plague or passover and killed out the grass (13), but that viewpoint is slowly dying out as the real cause of grass destruction and brush invasion is being understood. The primeval grasslands that were free of brush stayed free of brush because the dominating grasses had the strength to hold the land against invaders. When livestock crowded the ranges and ate down the best grasses first, the lower class plants which succeeded them were not strong enough to hold off the aggressive brush and trees. The original native grasses grow with trees and brush when correct grazing is practiced. On heavily grazed brush ranges, the only traces of original grasses are usually found within the thorny basal branches of brush, which guard the grasses against grazing animals. One Texas ranchman says that a sure clue to range improvement is when grazing lightens up so the good grasses can come out of the bushes into the open. Cedar and other evergreen plants with dense horizontal spreading branches shade the ground so completely that they afford little or no sanctuary to grasses. While the good grasses may flourish in brush land, they can never reach excellent condition until the trees or shrubs are killed out. Successful removal and control of dense stands of undesirable woody vegetation gives farmers and stockmen a major opportunity to conserve water and to increase forage production. In areas where there are dense stands of useless woody vegetation more water is lost by transpiration through the leaves each year than runs off down the draws, streams and rivers (1). For the most part woody plants on the range are water hogs. Some, like mesquite, require two to four times more water to grow a pound of dry leaves than do grasses.