A study over 33 years shows that carbon and nitrogen stocks in a subtropical soil are increasing under native vegetation in a changing climate.

Soil plays a critical role in the global carbon (C) cycle. However, climate change and associated factors, such as warming, precipitation change, elevated carbon dioxide (CO2), and atmospheric nitrogen (N) deposition, will affect soil organic carbon (SOC) stocks markedly - a decrease in SOC stocks is predicted to drive further planetary warming, although whether changes in climate and associated factors (including atmospheric N deposition) will cause a net increase in SOC or a net decrease is less certain. Using a subtropical soil, we have directly examined how changes over the last three decades are already impacting upon SOC stocks and soil total nitrogen (STN) in a Vertisol supporting native brigalow (Acacia harpophylla L.) vegetation. It was observed that SOC stocks increased under native vegetation by 5.85 Mg C ha-1 (0.177 ± 0.059 Mg C ha-1 y-1) at a depth of 0-0.3 m over 33 years. This net increase in SOC stocks was not correlated with change in precipitation, which did not change during the study period. Net SOC stocks, however, were correlated with an increasing trend in mean annual temperatures, with an average increase of 0.89 °C. This occurred despite a likely co-occurrence of increased decomposition due to higher temperatures, presumably because the increase in the SOC was largely in the stable, mineral-associated fraction. The increases in CO2 from 338 ppmv to 395 ppmv likely contributed to an increase in biomass, especially root biomass, resulting in the net increase in SOC stocks. Furthermore, STN stocks increased by 0.57 Mg N ha-1 (0.0174 ± 0.0041 Mg N ha-1 y-1) at 0-0.3 m depth, due to increased atmospheric N deposition and potential N2 fixation. Since SOC losses are often predicted in many regions due to global warming, these observations are relevant for sustainability of SOC stocks for productivity and climate models in semi-arid subtropical regions.

Tebuthiuron Movement via Leaching and Runoff from Grazed Vertisol and Alfisol Soils in the Brigalow Belt Bioregion of Central Queensland, Australia.

Tebuthiuron is one of five priority herbicides identified as a water pollutant entering the Great Barrier Reef. A review of tebuthiuron research in Australia found 13 papers, 6 of which focused on water quality at the basin scale (>10,000 km(2)) with little focus on process understanding. This study examined the movement of tebuthiuron in soil and runoff at the plot (1.7 m(2)) and small catchment (12.7 ha) scales. The greatest concentration and mass in soil occurred from 0 to 0.05 m depth 30-57 days after application. Concentrations at all depths tended to decrease after 55-104 days. Runoff at the small catchment scale contained high concentrations of tebuthiuron (average = 103 µg/L) 100 days after application, being 0.05% of the amount applied. Tebuthiuron concentrations in runoff declined over time with the majority of the chemical in the dissolved phase.

Turnover of organic carbon and nitrogen in soil assessed from δ13C and δ15N changes under pasture and cropping practices and estimates of greenhouse gas emissions.

The continuing clearance of native vegetation for pasture, and especially cropping, is a concern due to declines in soil organic C (SOC) and N, deteriorating soil health, and adverse environment impact such as increased emissions of major greenhouse gases (CO2, N2O and CH4). There is a need to quantify the rates of SOC and N budget changes, and the impact on greenhouse gas emissions from land use change in semi-arid subtropical regions where such data are scarce, so as to assist in developing appropriate management practices. We quantified the turnover rate of SOC from changes in δ(13)C following the conversion of C3 native vegetation to C4 perennial pasture and mixed C3/C4 cereal cropping (wheat/sorghum), as well as δ(15)N changes following the conversion of legume native vegetation to non-legume systems over 23 years. Perennial pasture (Cenchrus ciliaris cv. Biloela) maintained SOC but lost total N by more than 20% in the top 0-0.3m depth of soil, resulting in reduced animal productivity from the grazed pasture. Annual cropping depleted both SOC and total soil N by 34% and 38%, respectively, and resulted in decreasing cereal crop yields. Most of these losses of SOC and total N occurred from the >250 µm fraction of soil. Moreover, this fraction had almost a magnitude higher turnover rates than the 250-53 µm and <53 µm fractions. Loss of SOC during the cropping period contributed two-orders of magnitude more CO2-e to the atmosphere than the pasture system. Even then, the pasture system is not considered as a benchmark of agricultural sustainability because of its decreasing productivity in this semi-arid subtropical environment. Introduction of legumes (for N2 fixation) into perennial pastures may arrest the productivity decline of this system. Restoration of SOC in the cropped system will require land use change to perennial ecosystems such as legume-grass pastures or native vegetation.

Employer demand for health services researchers in the year 2020.

OBJECTIVE: To describe factors that will shape future demand for doctoral-trained health services researchers. STUDY DESIGN/DATA SOURCES: Commentary based on recent trends in funding for health services research (HSR), the number of federally funded HSR projects listed in HSRProj, national expenditures for health, and interviews with a small number of employers. PRINCIPAL FINDINGS: Despite rapid growth in the overall health care sector, inflation-adjusted funding for HSR has declined, implying little or no net growth in demand for people to lead HSR studies. Employers report being able to hire researchers to conduct HSR by drawing on people trained in many disciplines. CONCLUSION: Employers have considerable flexibility in hiring individuals to conduct HSR when demand is relatively stable. They may have much more difficulty hiring well-qualified researchers when faced with sharp increases in demand for HSR, such as could be generated by recent economic stimulus legislation.

Risk selection among SSI enrollees in TennCare.

The issue of risk selection is especially important for states that enroll blind and disabled beneficiaries of Supplemental Security Income (SSI) in Medicaid managed care. SSI beneficiaries have persistent needs for care, have a wide variety of chronic conditions, and often need atypical and complex services. Risk selection occurs when the health care needs of beneficiaries enrolled in a specific plan differ systematically from the needs of the overall beneficiary population and payments do not reflect those needs. We assess the extent of risk selection among managed care plans for SSI beneficiaries over the first three years of Tennessee's Medicaid managed care program, TennCare. Using claims data containing fee-for-service expenditures prior to enrollment in managed care, we find substantial evidence of persistent risk selection among plans. Results are robust to most alternative measures of risk selection for most plans.

Medicaid managed care and working-age beneficiaries with disabilities and chronic illnesses.

Even after a decade of study, there are still many questions about how working-age adults with disabilities or chronic illnesses are faring in Medicaid managed care. This article draws from recent research to examine two critical issues: the need for better outcome measures specific to this population and the importance of evaluations that accurately estimate program effects, despite continued policy change, considerable differences among States, and extreme population diversity. The authors outline a research agenda that will help policymakers develop a more precise sense of how managed care practices affect different subgroups of working-age adults with disabilities and chronic illnesses and how practices could be altered to improve Medicaid's ability to meet their needs.

Profile of Medicare Beneficiaries With AIDS: Application of an AIDS Casefinding Algorithm.

This profile of Medicare beneficiaries with acquired immunodeficiency syndrome (AIDS) was developed by applying a casefinding algorithm to virtually all Medicare claims from 1991-93. The algorithm identified more than 37,000 beneficiaries with AIDS, approximately 21,000 of whom were living at the end of 1993. These estimates suggest that as many as 12 percent of people living with AIDS at the end of 1993 were covered by Medicare. Medicare expenditures for these beneficiaries averaged more than $2,400 per month and totaled more than $500 million in 1993. These expenditures are likely to rise as more people with AIDS live long enough to qualify for Medicare coverage.