Evaluation of Locally-Adapted Native Seed Sources and Impacts of Livestock Grazing for Restoration of Historic Oil Pad Sites in South Texas

Abstract

Oil and gas activities, particularly road and drilling pad construction, impact large acreages of native rangelands across the country. Many landowners attempt to restore the pad sites of historic wells to native vegetation with varying results. To test the ability of a locally-adapted, native seed mix, made up of grasses, forbs, and legumes, we attempted to restore four former oil and gas wells to their historic grassland state. Adding to the complexity of the restoration process, these pads were located within large grazing units, making it unfeasible to exclude grazing. We evaluated the ability of the native seed mix to establish and persist, and the effects of grazing by cattle the on the restored sites for two years after planting. By seven months post seeding, we were able to establish restored species density of ≥ 0.9 seeded plants/m², comprising of an average of eight different species. Cattle grazing had little effect on the density of seeded species. Cattle grazing did have minor effects on species composition; however, these effects are not likely to create any long term effects on species composition. These results are promising to landowners attempting to perform native grassland restoration following oil and gas activities in South Texas, even when livestock exclusion is impractical.