Hydraulic diversity of forests regulates ecosystem resilience during drought.

Plants influence the atmosphere through fluxes of carbon, water and energy1, and can intensify drought through land-atmosphere feedback effects2-4. The diversity of plant functional traits in forests, especially physiological traits related to water (hydraulic) transport, may have a critical role in land-atmosphere feedback, particularly during drought. Here we combine 352 site-years of eddy covariance measurements from 40 forest sites, remote-sensing observations of plant water content and plant functional-trait data to test whether the diversity in plant traits affects the response of the ecosystem to drought. We find evidence that higher hydraulic diversity buffers variation in ecosystem flux during dry periods across temperate and boreal forests. Hydraulic traits were the predominant significant predictors of cross-site patterns in drought response. By contrast, standard leaf and wood traits, such as specific leaf area and wood density, had little explanatory power. Our results demonstrate that diversity in the hydraulic traits of trees mediates ecosystem resilience to drought and is likely to have an important role in future ecosystem-atmosphere feedback effects in a changing climate.

Smart Tactical Application Tourniquet Versus Combat Application Tourniquet: Comparing Layperson Applications for Arterial Occlusion After a Video Demonstration.

BACKGROUND: Tourniquet efficacy for extremity hemorrhage is well established, although literature demonstrates variable first responder application efficacy. Several newer models, including the Smart Tactical Application Tourniquet (STAT, STAT Medical Devices, LLC, Freehold, New Jersey), offer alternatives to well-established devices like the Combat Application Tourniquet (CAT, C-A-T Resources, LLC, Rock Hill, South Carolina). Newer models are commercially sold without significant literature regarding efficacy or user feedback. We developed a pilot study to compare CAT and STAT applications for layperson hemorrhage control efficacy after a brief, standardized instructional video. STUDY DESIGN AND METHODS: This is a prospective randomized observational study that utilized layperson volunteers for the application of STAT or CAT. After a demographic survey, volunteers were randomized and watched the respective tourniquet instructional video, then applied the tourniquet to a HapMed hemorrhage simulator. The application was assessed for trial time, time to hemorrhage control, occlusion pressure, and total blood loss. Investigators also evaluated volunteers for proper application and received user feedback. RESULTS: Eighty-four total volunteers (42 CAT, 42 STAT) completed testing. Volunteers applied the CAT (50.0%, n = 21) with significantly greater rates of success than the STAT (0%, n = 0, p < 0.001). The CAT demonstrated significantly greater average occlusion pressure compared to the STAT (409.9 mm Hg vs. 116.5 mm Hg, p < 0.001). Similarly, CAT application resulted in significantly less average blood loss compared to the STAT (577.8 mL vs. 974.6 mL, p < 0.001). On the 5-point Likert scale, volunteers reported significantly higher benefits from video instruction and comfort with tourniquet application with the CAT over the STAT (4.7 vs. 4.0, p < 0.001, 4.0 vs. 2.4, p < 0.001). CONCLUSIONS: When performed by laypersons with minimal video instruction, the CAT was applied with significantly higher rates of success, higher mean occlusion pressures, reduced blood loss, and higher end-user ratings than the STAT.