Historical Changes and Trendsin Livestock Numbers Across Ecoregions in Texas

Historically, rangelands were managed to reduce brush and increase livestock grazing habitat. As with much of the southwestern United States, the seemingly endless ―free grass‖ of Texas rangelands was overgrazed during the late 1800s. Overgrazing reduced fine fuel loads and, combined with disruption in fire regimes, allowed woody plants populations to invade grasslands. Consequently, livestock carrying capacity ultimately declined. Because livestock overgrazing has a central role in land degradation and woody plant encroachment, I analyzed historical livestock numbers to identify potential trends that can generate and be integrated into future hypotheses of land use change. The counties included in four ecoregions of Texas (Edwards Plateau, Lampasas Cut Plains, South Texas, and West Texas) were selected based on the existence of historically uncultivated rangelands. I collected data from the U.S. Census of Agriculture and graphically explored trends in livestock numbers. Although livestock numbers varied across time and by region, three general hypotheses could be identified: a) livestock numbers are direct drivers of degradation and indirect drivers of woody plant encroachment; b) for rangelands threatened by woody plant encroachment, decreasing livestock numbers may be associated with recovery of rangelands in an ecoregion; and, c) given transformation of the landscape from rangelands to woodlands, decreases in livestock numbers over time are related to increases in key indicators of ecosystem health (e.g., ground water flow). This historical analysis provides insight to complex human-ecological interactions and will be used as supporting data for further studies regarding ecosystem health and services