Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest

Measuring in situ soil fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) continuously at high frequency requires appropriate technology. We tested the combination of a commercial automated soil CO2 flux chamber system (LI-8100A) with a CH4 and N2O analyzer (Picarro G2308) in a tropical rainforest for 4 months. A chamber closure time of 2 min was sufficient for a reliable estimation of CO2 and CH4 fluxes (100 % and 98.5 % of fluxes were above minimum detectable flux - MDF, respectively). This closure time was generally not suitable for a reliable estimation of the low N2O fluxes in this ecosystem but was sufficient for detecting rare major peak events. A closure time of 25 min was more appropriate for reliable estimation of most N2O fluxes (85.6 % of measured fluxes are above MDF ± 0.002 nmol m−2 s−1). Our study highlights the importance of adjusted closure time for each gas

A symptom-based algorithm for calcium management after thyroid surgery: a prospective multicenter study

Objective: Evidence-based treatment guidelines for the management of postthyroidectomy hypocalcemia are absent. The aim of this study was to evaluate a newly developed symptom-based treatment algorithm including a protocolized attempt to phase out supplementation. Methods: In a prospective multicenter study, patients were treated according to the new algorithm and compared to a historical cohort of patients treated with a biochemically based approach. The primary outcome was the proportion of patients receiving calcium and/or alfacalcidol supplementation. Secondary outcomes were calcium-related complications and predictors for supplementation. Results: One hundred thirty-four patients were included prospectively, and compared to 392 historical patients. The new algorithm significantly reduced the proportion of patients treated with calcium and/or alfacalcidol during the first postoperative year (odds ratio (OR): 0.36 (95% CI: 0.23–0.54), P < 0.001), and persistently at 12 months follow-up (OR: 0.51 (95% CI: 0.28–0.90), P < 0.05). No severe calcium-related complications occurred, even though calcium-related visits to the emergency department and readmissions increased (OR: 11.5 (95% CI: 4.51–29.3), P <0.001) and (OR: 3.46 (95% CI: 1.58–7.57), P < 0.05), respectively. The proportional change in pre- to post operative parathyroid hormone (PTH) was an independent predictor for supplementation (OR: 1.04 (95% CI: 1.02–1.07), P < 0.05). Conclusions: Symptom-based management of postthyroidectomy hypocalcemia and a protocolized attempt to phase out supplementation safely reduce d the proportion of patients receiving supplementation, although the number of calcium-related hospital visits increased. For the future, we envision a more individualized treatment approach for patients at risk for delayed symptomatic hypocalcemia, including the proportional change in pre- to post- operative PTH

The Helminthosporium Foot-rot of Wheat, with Observations on the Morphology of Helminthosporium and on the Occurrence of Saltation in the Genus

is peer reviewedOpe

Does the stress tolerance of mixed grassland communities change in a future climate? A test with heavy metal stress (zinc pollution)

Will species that are sensitive/tolerant to Zn pollution still have the same sensitivity/tolerance in a future climate? To answer this question we analysed the response of constructed grassland communities to five levels of zinc (Zn) supply, ranging from 0 to 354 mg Zn kg(-1) dry soil, under a current climate and a future climate (elevated CO(2) and warming). Zn concentrations increased in roots and shoots with Zn addition but this increase did not differ between climates. Light-saturated net CO(2) assimilation rate (A(sat)) of the species, on the other hand, responded differently to Zn addition depending on climate. Still, current and future climate communities have comparable biomass responses to Zn, i.e., no change in root biomass and a 13% decrease of above-ground biomass. Provided that the different response of A(sat) in a future climate will not compromise productivity and survival on the long term, sensitivity is not altered by climate change. (C) 2011 Elsevier Ltd. All rights reserved

Does an extreme drought event alter the response of grassland communities to a changing climate?

Global temperatures and atmospheric CO(2) concentrations are expected to both increase, but their combined effect on plant communities has been far less investigated than the single factors of global change. Moreover, drought events are expected to become more frequent and intense in the near future what might alter plant responses to the changing climate. In this study synthesised grassland communities in a current or future climate were subjected to several drought levels (0, 15, 22 and 35 days of drought). The grassland communities were grown in six sunlit, climate-controlled chambers. Three of the chambers were exposed to ambient temperature and CO(2) (current climate), while the other three were continuously warmed 3 degrees C above ambient temperature at 620 ppm of CO(2) (future climate). The aim of this study was to investigate the effect of drought on the response of grassland communities to a future climate. Therefore, the response to future climate was observed (1) in the absence of drought and (2) in the occurrence of an extreme drought event, both early and late in the growing season. (1) In the absence of drought, plant productivity was positively affected by future climate early in the growing season. Later in the growing season this effect tended to turn negative, resulting in a disappearance of the overall effect of climate at the end of the growing season. (2) During drought there was a stronger decrease in net CO(2) assimilation rate (A(sat)) in future than in current climate due to stronger stomata! closure. Consistently, the beneficial biomass response to future climate stagnated during drought. At the end of the season, after a period of recovery, there was no effect of climate on plant productivity. As in the absence of drought, plant productivity was not affected by climate at the end of the growing season. Hence, the occurrence of an extreme drought event during the growing season did not alter the overall response of plant productivity to a future climate. (C) 2010 Elsevier B.V. All rights reserved

Do interactions with neighbours modify the above-ground productivity response to drought? A test with two grassland species

Natural systems are predicted to be exposed to more frequent and more intense drought events in the near future. Plant-plant interactions form an important part of the whole of mechanisms that govern the responses of plant species and communities to drought. The accuracy of predictions on ecosystem functioning would therefore be improved by determining when plant interactions need to be considered and how these interactions can drive species responses. In this study, we assessed the effect of neighbour plants on the drought response of a target plant. Two grassland species (Plantago lanceolate and Lolium perenne) were grown in the presence of either six conspecific or three conspecific and three heterospecific neighbours in sunlit growth chambers. They were subjected to drought by withholding water for 20 days. Regardless of the identity of the target plant, having P. lanceolate as a neighbour increased the susceptibility to negative drought effects on biomass production while L. perenne neighbours buffered the target's drought response. Our results therefore suggest that drought responses depended largely on the identity and the traits of the neighbours. Such findings demonstrate that current models to predict ecosystem functioning may be misleading by not sufficiently taking plant-plant interactions into account. (C) 2014 Elsevier B.V. All rights reserved

Altered response to nitrogen supply of mixed grassland communities in a future climate : a controlled environment microcosm study

Few studies have investigated whether responses to nutrient supply of mixed plant communities change under combined elevated CO(2) and climate warming. In this study we analyzed the response of constructed temperate grassland communities to five levels of nitrogen (N) supply, ranging from 0 to 150 kg N ha(-1), under two climate scenarios. Biomass of the plant communities responded positively to N supply in the current climate, but was insensitive to N supply in the future climate. This altered response was not the result of a changing response from a single species, but all species seemed to contribute to it. The weaker response in the future climate was caused by changes in N uptake rather than by changes in nitrogen use efficiency, as community N stocks showed the same response pattern as community biomass. Climate change apparently modified the relation between fertilizer N addition and plant available N