The LTAR-integrated grazing land common experiment at the Texas Gulf.

Extreme weather and climate events have become more frequent and directly affect the ecological structure and function of integrated grazing lands. While the Great Plains have experienced a long history of regular disturbances from drought and floods, grazing, and fires, the increased frequency and magnitude of these disturbances can reduce ecological resilience, largely depending on management practices. Alternative strategies designed to adaptively manage grazing land resources based on the ecology of the system should increase the resistance and resilience to disturbances when compared to prevailing practices. Determining the ecologic and economic value of alternative strategies will require long-term evaluations across large spatial scales. The Long-Term Agroecosystem Research Network has been established to evaluate the differences between alternative and prevailing practices among 18 strategically located sites and across decadal time scales throughout the continental United States. A key integrated grazing land site within this network is the Texas Gulf located at the Riesel Watersheds in the Blackland Prairie of Central Texas. At this study site, the differences between alternative and prevailing grazing management strategies are now being evaluated. The alternative strategy was designed using a combination of knowledge of the site and species ecology with modern-day tools and technologies. Alternatively, the prevailing practice implements a conventional year-round continuous grazing system with heavy reliance on hay and supplemental protein during winter. Results will provide grazing land managers with economically viable adaptive management choices for increasing ecological resilience following extreme and frequent disturbance events.

Effects of urbanization and climate change on stream health in north-central Texas.

Estimation of stream health involves the analysis of changes in aquatic species, riparian vegetation, microinvertebrates, and channel degradation due to hydrologic changes occurring from anthropogenic activities. In this study, we quantified stream health changes arising from urbanization and climate change using a combination of the widely accepted Indicators of Hydrologic Alteration (IHA) and Dundee Hydrologic Regime Assessment Method (DHRAM) on a rapidly urbanized watershed in the Dallas-Fort Worth metropolitan area in Texas. Historical flow data were split into pre-alteration and post-alteration periods. The influence of climate change on stream health was analyzed by dividing the precipitation data into three groups of dry, average, and wet conditions based on recorded annual precipitation. Hydrologic indicators were evaluated for all three of the climate scenarios to estimate the stream health changes brought about by climate change. The effect of urbanization on stream health was analyzed for a specific subwatershed where urbanization occurred dramatically but no stream flow data were available using the widely used watershed-scale Soil and Water Assessment Tool (SWAT) model. The results of this study identify negative impacts to stream health with increasing urbanization and indicate that dry weather has more impact on stream health than wet weather. The IHA-DHRAM approach and SWAT model prove to be useful tools to estimate stream health at the watershed scale.