Recent severe droughts the south-central United States led to high levels of woody plant dieback in areas that have experienced decades of woody encroachment. These droughts were the most severe droughts on record since the 1950s. Following the 1950s drought, a study was conducted on the Edwards Plateau at the Sonora, Texas Agrilife Research Station to quantify rates of dieback in density and cover for various woody plant species. We repeated this study in 2011 within the same pastoral treatments that have been managed consistently since 1948. While the 1950s drought resulted in more severe reductions in total woody plant cover (44% decrease in cover in 1959 compared to 18% decrease in 2011), patterns of dieback were relatively similar following both drought periods. Major shifts from one plant community to another were not observed after either drought. Rather, shifts in vegetation were patch-specific and contingent on variable species responses to interactions among soil types, pastoral livestock treatments, and woody plant densities. This suggests that drought-induced shifts in woody vegetation are primarily driven by differences in ecohydrology among soil types of the Edwards Plateau and the water use strategy of the dominant woody species. These small-scale vegetation shifts pose a challenge for scientists attempting to develop accurate predictions of species-level responses to climate change. More studies are needed to determine the importance of legacy effects related to long-term land management, woody plant densities, plant demography, differences in ecohydrology among soil types, and other factors which potentially contribute to woody plant dieback.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.