Effects of Mowing on Methane Uptake in a Semiarid Grassland in Northern China

Background: Mowing is a widely adopted management practice for the semiarid steppe in China and affects CH4 exchange. However, the magnitude and the underlying mechanisms for CH 4 uptake in response to mowing remain uncertain. Methodology/Principal Findings: In two consecutive growing seasons, we measured the effect of mowing on CH 4 uptake in a steppe community. Vegetation was mowed to 2 cm (M2), 5 cm (M5), 10 cm (M10), 15 cm (M15) above soil surface, respectively, and control was set as non-mowing (NM). Compared with control, CH4 uptake was substantially enhanced at almost all the mowing treatments except for M15 plots of 2009. CH4 uptake was significantly correlated with soil microbial biomass carbon, microbial biomass nitrogen, and soil moisture. Mowing affects CH 4 uptake primarily through its effect on some biotic factors, such as net primary productivity, soil microbial C\N supply and soil microbial activities, while soil temperature and moisture were less important. Conclusions/Significance: This study found that mowing affects the fluxes of CH4 in the semiarid temperate steppe of north China

Review on the validity of self-report to assess work-related diseases

Self-report is an efficient and accepted means of assessing population characteristics, risk factors, and diseases. Little is known on the validity of self-reported work-related illness as an indicator of the presence of a work-related disease. This study reviews the evidence on (1) the validity of workers' self-reported illness and (2) on the validity of workers' self-assessed work relatedness of an illness. A systematic literature search was conducted in four databases (Medline, Embase, PsycINFO and OSH-Update). Two reviewers independently performed the article selection and data extraction. The methodological quality of the studies was evaluated, levels of agreement and predictive values were rated against predefined criteria, and sources of heterogeneity were explored. In 32 studies, workers' self-reports of health conditions were compared with the "reference standard" of expert opinion. We found that agreement was mainly low to moderate. Self-assessed work relatedness of a health condition was examined in only four studies, showing low-to-moderate agreement with expert assessment. The health condition, type of questionnaire, and the case definitions for both self-report and reference standards influence the results of validation studies. Workers' self-reported illness may provide valuable information on the presence of disease, although the generalizability of the findings is limited primarily to musculoskeletal and skin disorders. For case finding in a population at risk, e.g., an active workers' health surveillance program, a sensitive symptom questionnaire with a follow-up by a medical examination may be the best choice. Evidence on the validity of self-assessed work relatedness of a health condition is scarce. Adding well-developed questions to a specific medical diagnosis exploring the relationship between symptoms and work may be a good strateg

The development of an evidence-based patient booklet for patients undergoing lumbar discectomy and un-instrumented decompression

Post-operative management after lumbar surgery is inconsistent leading to uncertainty amongst surgeons and patients about post-operative restrictions, reactivation, and return to work. This study aimed to review the evidence on post-operative management, with a view to developing evidence-based messages for a patient booklet on post-operative management after lumbar discectomy or un-instrumented decompression. A systematic literature search produced a best-evidence synthesis of information and advice on post-operative restrictions, activation, rehabilitation, and expectations about outcomes. Evidence statements were extracted and developed into patient-centred messages for an educational booklet. The draft text was evaluated by peer and patient review. The literature review found little evidence for post-operative activity restrictions, and a strong case for an early active approach to post-operative management. The booklet was built around key messages derived from the literature review and aimed to reduce uncertainty, promote positive beliefs, encourage early reactivation, and provide practical advice on self-management. Feedback from the evaluations were favourable from both review groups, suggesting that this evidence-based approach to management is acceptable and it has clinical potentia

Comparison of methane, nitrous oxide fluxes and CO2 respiration rates from a Mediterranean cork oak ecosystem and improved pasture

Background and aims: During the recent decades, cork oak (Q. suber) mortality has been increasing in Mediterranean oak woodland endangering the economical and environmental sustainability of the “montado” ecosystem. This fact in combination with climate change and conversion of forestland to pasture may significantly affect the soil-atmosphere greenhouse gases (GHGs) exchange. Our study evaluates the impact of oak trees as compared to pasture on net ecosystem GHG (CH4, N2O, and CO2) exchange as well as the main environmental factors influencing this exchange. Methods: We used field chamber measurements for the collection of GHGs under three different conditions: 1) open area (OA), 2) under tree canopy area (UC) and 3) improved pasture (IP). Experiments were done under typical Mediterranean climate at central Portugal in 2010 and 2011. Results: The UC had higher nitrification potential, soil C/N ratio, electrical conductivity, litter input and soil organic matter (SOM) than OA and IP. SOM positively correlated with soil CH4 and N2O fluxes but not with soil CO2 respiration rates. Soil water content (SWC) drives both CH4 and N2O fluxes. Under certain conditions, when SWC reached a threshold (7 % for CH4 and 3 % for N2O) the result was net uptake and that net uptake increased with SWC. This was the case for the UC and OA. Conversely, for the IP soil water content above 4 % promoted net CH4 release. Conclusions: Our results show that cork oak influences soil properties and consequently GHGs fluxes. In the UC the input of litter for SOM together with soil moisture, favoured microbiological activity and related GHGs fluxes. Soil temperature is a secondary factor in the studied conditions. Our results also emphasized the potential impact posed by decreased cork oak tree density in the functioning of the “montado” ecosystem. Keywords Evergreen oak . Greenhouse gases