Increasing aridity reduces soil microbial diversity and abundance in global drylands

Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy ∼41% of Earth´s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and α-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climate-change models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands.Climate change is a major driver of biodiversity loss from local to global scales, in both terrestrial and aquatic ecosystems (1, 2). Given the dependence of crucial ecosystem processes and services on biodiversity (3–5), climate-change-driven biodiversity losses will dramatically alter the functioning of natural ecosystems (4, 6). Key ecosystem processes—such as nutrient cycling, carbon (C) sequestration, and organic matter decomposition—depend on soil bacteria and fungi (7–9). However, we have limited knowledge of the role of climatic factors as drivers of their abundance and diversity at regional and global scales (10–12). This gap in our understanding is particularly true for drylands, areas with an aridity index (precipitation/potential evapotranspiration ratio) below 0.65 (13), which are among the most sensitive ecosystems to climate change (14). Drylands are expected to expand in global area by 11–23% by 2100 (15), experiencing increased aridity and reduced soil moisture (16). Land degradation and desertification already affect ∼250 million people in the developing world (17). Altered climate and the growth of human populations will almost inevitably exacerbate these problems in drylands (14, 17). Because the provisioning of ecosystem services essential for human development (e.g., soil fertility, food, and biomass production) heavily relies on the abundance, composition, and diversity of soil fungi and bacteria (18, 19), it is crucial to understand how changes in aridity affect soil microbial communities. Drylands, however, are poorly represented in global soil bacteria and fungi databases (10–12, 20), and no field study has simultaneously examined how the abundance, composition, and diversity of these organisms vary along aridity gradients in drylands worldwide.Here, we present a global field study conducted across 80 dryland sites from all continents, except Antarctica (Fig. S1), to assess how changes in aridity, as defined by the aridity index, affect the total abundance and diversity of soil bacteria and fungi and the relative abundance of major bacterial and fungal taxa. The studied ecosystems encompass a wide variety of the climatic, edaphic, and vegetation conditions found in drylands worldwide (Materials and Methods). We predict that increases in aridity should reduce the abundance and diversity of soil bacteria and fungi due to the negative relationships typically found between aridity and the availability of resources such as water and C (21), which largely drive soil microbial abundance and activity in drylands (22–24). To test this hypothesis, we characterized bacterial and fungal communities in the soil surface (top 7.5 cm) along natural aridity gradients by using Illumina Miseq profiling of ribosomal genes and internal transcribed spacer (ITS) markers, quantified bacterial and fungal abundances with quantitative PCR (qPCR), and gathered information on multiple biotic and abiotic factors known to influence soil microbes (Fig. S2).Open in a separate windowFig. S1.Location of the 80 sites used in this study. Some of them overlap and are thus indistinguishable. Exact locations and additional site characteristics are provided in figshare (DOI 10.6084/m9.figshare.1487693).Open in a separate windowFig. S2.A priori SEM used in this study. Spatial is a composite variable formed by latitude and longitude. MDR, mean diurnal temperature range (mean of monthly differences between maximum and minimum temperature). The numbers in the arrows denote example references used to support our predictions, which can be found in the reference list.     

A medical school for international health run by international partners.

In early 1996, the Ben Gurion University Faculty of Health Sciences (BGU), Beer-Sheva, Israel, in collaboration with Columbia University Medical Center (CUMC), New York City, United States, decided to found a second medical school within BGU, the Medical School for International Health (MSIH), to prepare students to work both in medicine and in cross-cultural and international health and medicine (IHM). Methods used to establish and jointly run MSIH include (1) defining clearly the tasks of each university according to how it can best contribute to the new school; (2) establishing an organizational structure in each university for accomplishing these tasks; (3) establishing clear communication between the two organizational structures; (4) defining outcomes to measure success; and (5) developing methods for addressing management problems. CUMC's functions were admission, public relations, and the fourth-year elective program. BGU's functions were developing and running an innovative curriculum, including a four-year required track in IHM, evaluating students, taking the lead in helping students' with their personal problems, and managing financial aid. The first students were admitted in 1998. Variables reflecting MSIH's success include scores on the United States Medical Licensing Examination, residency placement, the attrition rate, and success in preparing students in IHM (e.g., success in learning cross-cultural medicine and the percentage of students who work in IHM). MSIH is running well and has solved its inter-university management problems. Its 85 graduates matched at very good to excellent U.S. hospitals and have learned and maintained enthusiasm for the IHM curriculum.     

Sustained Reduction in Health Disparities Achieved through Targeted Quality Improvement: One‐Year Follow‐up on a Three‐Year Intervention

Objective

To assess a quality improvement disparity reduction intervention and its sustainability.

Data Sources/Study Setting

Electronic health records and Quality Index database of Clalit Health Services in Israel (2008–2012).

Study Design

Interrupted time‐series with pre‐, during, and postintervention disparities measurement between 55 target clinics (serving approximately 400,000 mostly low socioeconomic, minority populations) and all other (126) clinics.

Data Collection/Extraction Methods

Data on a Quality Indicator Disparity Scale (QUIDS‐7) of 7 indicators, and on a 61‐indicator scale (QUIDS‐61).

Principal Findings

The gap between intervention and nonintervention clinics for QUIDS‐7 decreased by 66.7 percent and by 70.4 percent for QUIDS‐61. Disparity reduction continued (18.2 percent) during the follow‐up period.

Conclusions

Quality improvement can achieve significant reduction in disparities in a wide range of clinical domains, which can be sustained over time.     

Outcome and survival following tracheostomy in patients ≥ 85 years old

European Archives of Oto-Rhino-Laryngology - To evaluate percutaneous dilatational tracheostomy in patients ≥ 85 years old: its complication rate and possible risk...     

Sex Differences in Infective Endocarditis

BackgroundThe impact of sex on the presentation, etiology, and outcomes of infective endocarditis (IE) has not been adequately studied. The aim of the present research was to analyze the impact of sex on the presentation, etiology, and outcomes of IE.MethodsWe performed a retrospective study of 214 adult patients (131 male and 83 female) with IE. All cases of IE were reviewed by two investigators- both senior physicians in internal medicine. Two groups of patients were compared: male and female patients with IE. The primary outcome was in-hospital mortality.ResultsWe found significant differences in etiologic factors of IE in male and female patients. Microbiologic etiology differences between male and female groups of patients were in coagulase negative staphylococcus (15.0% in male vs 3.8% in female groups, P = 0.011), and culture negative endocarditis (8.7% in male vs 23.8% in female groups, P = 0.004). We did not find a difference in the primary outcome between the two groups; however, all-cause mortality was significantly higher in the female group as compared to the male group (26 [31.3] vs 22 [16.8], P = 0.018).ConclusionsWe found that sex may have important role in both the microbial profile and the patient's outcome with IE.