The Impact of Soil Water Storage Capacity on Species-specific Forb Establishment in CP42 Fields

The loss of tallgrass prairie habitat has negatively impacted North American pollinator communities. To combat this loss, the Conservation Reserve Program (CRP) created Conservation Practice (CP) 42 to establish new pollinator habitat on the landscape. A two-year vegetation survey of CP42 sites in Iowa revealed high variability in overall quality (e.g., the ratio of sown forb-to-weed stems ranged from 9:1 to 1:9 across sites ). To examine potential causes of this variability, we assessed whether soil water storage capacity and corn suitability rating influence species-specific forb establishment in 35 surveyed CP42 fields. We estimated forb establishment for the seven most commonly sown species across sites as the number of plants per acre divided by the number of sown pure live seeds per acre. The water storage capacity and corn suitability rating (CSR2) of each site was obtained from the Iowa Soil Survey. We hypothesized that sites with higher soil water storage capacities and corn suitability ratings would have higher forb establishment. Corn suitability rating did not influence establishment in any of the seven sown forb species. Soil water storage capacity only influenced establishment in one species: sites with lower water storage capacity had higher Rudbeckia hirta establishment. Overall, our results suggest that soil moisture and overall soil quality metrics have little predictive power for the outcome of CP42 plantings

Vascular access survival and incidence of revisions: A comparison of prosthetic grafts, simple autogenous fistulas, and venous transposition fistulas from the United States Renal Data System Dialysis Morbidity and Mortality Study

AbstractObjective: The study's aim was to evaluate access patency and incidence of revisions in patients initiating hemodialysis and to determine differences in access performance by type of access among patient subgroups. Methods: The study used data from the United States Renal Data System Dialysis Morbidity and Mortality Study Wave 2, which contained a random sample of dialysis patients initiating dialysis in 1996 and early 1997. Failures and revisions were evaluated among 2247 newly placed hemodialysis accesses by using Cox proportional hazards regression model and Poisson regression. Primary and secondary patency rates were estimated using the Kaplan-Meier method. Results: Fifteen hundred seventy-four prosthetic grafts, 492 simple autogenous fistulas, and 181 venous transposition fistulas were available for evaluation. Prosthetic grafts had a 41% greater risk of primary failure compared with simple fistulas (relative risk, 1.41; 95% CI, 1.22-1.64; P <.001) and a 91% higher incidence of revision (relative risk, 1.91; 95% CI, 1.60-2.28; P <.001). At 2 years, autogenous fistulas demonstrated superior primary patency (39.8% versus 24.6%, P <.001) and equivalent secondary patency (64.3% versus 59.5%, P =.24) compared with prosthetic grafts. When compared with simple fistulas, vein transpositions demonstrated equivalent secondary patency at 2 years (61.5% versus 64.3%, P =.43) but inferior primary patency (27.7% versus 39.8%, P =.008) and had a 32% increased incidence of revision (P =.04). Autogenous fistulas had superior primary patency compared with prosthetic grafts in all patient subgroups except for patients with previously failed access. Vein transpositions showed the greatest benefit in terms of patency and incidence of revision in women and in patients with previously failed access. Conclusions: The preferential placement of autogenous fistulas may increase primary patency and decrease the incidence of revisions. Vein transpositions had similar secondary patency compared with simple fistulas, but required more revisions. The greatest benefit of a vein transposition fistula was seen in women and in patients with a history of access failure. (J Vasc Surg 2001;34:694-700.