Carbon inputs from Miscanthus displace older soil organic carbon without inducing priming

The carbon (C) dynamics of a bioenergy system are key to correctly defining its viability as a sustainable alternative to conventional fossil fuel energy sources. Recent studies have quantified the greenhouse gas mitigation potential of these bioenergy crops, often concluding that C sequestration in soils plays a primary role in offsetting emissions through energy generation. Miscanthus is a particularly promising bioenergy crop and research has shown that soil C stocks can increase by more than 2 t C ha−1 yr−1. In this study, we use a stable isotope (13C) technique to trace the inputs and outputs from soils below a commercial Miscanthus plantation in Lincolnshire, UK, over the first 7 years of growth after conversion from a conventional arable crop. Results suggest that an unchanging total topsoil (0–30 cm) C stock is caused by Miscanthus additions displacing older soil organic matter. Further, using a comparison between bare soil plots (no new Miscanthus inputs) and undisturbed Miscanthus controls, soil respiration was seen to be unaffected through priming by fresh inputs or rhizosphere. The temperature sensitivity of old soil C was also seen to be very similar with and without the presence of live root biomass. Total soil respiration from control plots was dominated by Miscanthus-derived emissions with autotrophic respiration alone accounting for ∼50 % of CO2. Although total soil C stocks did not change significantly over time, the Miscanthus-derived soil C accumulated at a rate of 860 kg C ha−1 yr−1 over the top 30 cm. Ultimately, the results from this study indicate that soil C stocks below Miscanthus plantations do not necessarily increase during the first 7 years

Earth Virtualization Engines (EVE)

To manage Earth in the Anthropocene, new tools, new institutions, and new forms of international cooperation will be required. Earth Virtualization Engines is proposed as an international federation of centers of excellence to empower all people to respond to the immense and urgent challenges posed by climate change

Earth Virtualization Engines (EVE)

To manage Earth in the Anthropocene, new tools, new institutions, and new forms of international cooperation will be required. Earth Virtualization Engines is proposed as an international federation of centers of excellence to empower all people to respond to the immense and urgent challenges posed by climate change

Carbon cycle extremes during the 21st century in CMIP5 models: Future evolution and attribution to climatic drivers

Climate extremes such as droughts and heatwaves aect terrestrial ecosystems and may alter local carbon budgets. However, it still remains uncertain to what degree extreme impacts in the carbon cycle in uence the carbon cycle-climate feedback both today and the near future. Here, we analyze spatiotemporally contiguous negative extreme anomalies in gross primary production (GPP) and net ecosystem production (NEP) in model output of the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble and investigate their future development and attribution to climatic drivers. We nd that relative to the overall increase in global carbon uptake, negative extremes in GPP and NEP lose importance towards the end of the 21st century. This eect can be related to elevated CO2 concentrations and higher amounts of available water at the global scale, partially mitigating the impacts of droughts and heatwaves, respectively. Overall, based on CMIP5 models we hypothesize that terrestrial ecosystems might be more resilient against future climate extremes than previously thought. Future work will have to further scrutinize these results considering that various biological and biogeochemical feedbacks are not yet integrated within earth system models

Carbon cycle extremes during the 21st century in CMIP5 models: Future evolution and attribution to climatic drivers

Climate extremes such as droughts and heat waves affect terrestrial ecosystems and may alter local carbon budgets. However, it still remains uncertain to what degree extreme impacts in the carbon cycle influence the carbon cycle-climate feedback both today and the near future. Here we analyze spatiotemporally contiguous negative extreme anomalies in gross primary production (GPP) and net ecosystem production (NEP) in model output of the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble and investigate their future development and attribution to climatic drivers. We find that relative to the overall increase in global carbon uptake, negative extremes in GPP and NEP lose importance toward the end of the 21st century. This effect can be related to elevated CO2 concentrations and higher amounts of available water at the global scale, partially mitigating the impacts of droughts and heat waves, respectively. Overall, based on CMIP5 models, we hypothesize that terrestrial ecosystems might be more resilient against future climate extremes than previously thought. Future work will have to further scrutinize these results considering that various biological and biogeochemical feedbacks are not yet integrated within Earth system models. Key Points Relative impact of negative extremes in GPP and NEP does not increase till 2100Negative extremes in GPP and NEP are driven by concurrent dry and hot condition

A few extreme events dominate global interannual variability in gross primary production

Understanding the impacts of climate extremes on the carbon cycle is important for quantifying the carbon-cycle climate feedback and highly relevant to climate change assessments. Climate extremes and fires can have severe regional effects, but a spatially explicit global impact assessment is still lacking. Here, we directly quantify spatiotemporal contiguous extreme anomalies in four global data sets of gross primary production (GPP) over the last 30 years. We find that positive and negative GPP extremes occurring on 7% of the spatiotemporal domain explain 78% of the global interannual variation in GPP and a significant fraction of variation in the net carbon flux. The largest thousand negative GPP extremes during 1982-2011 (4.3% of the data) account for a decrease in photosynthetic carbon uptake of about 3.5 Pg C yr-1, with most events being attributable to water scarcity. The results imply that it is essential to understand the nature and causes of extremes to understand current and future GPP variability. © 2014 IOP Publishing Ltd

A few extreme events dominate global interannual variability in gross primary production

Understanding the impacts of climate extremes on the carbon cycle is important for quantifying the carbon-cycle climate feedback and highly relevant to climate change assessments. Climate extremes and fires can have severe regional effects, but a spatially explicit global impact assessment is still lacking. Here, we directly quantify spatiotemporal contiguous extreme anomalies in four global data sets of gross primary production (GPP) over the last 30 years. We find that positive and negative GPP extremes occurring on 7% of the spatiotemporal domain explain 78% of the global interannual variation in GPP and a significant fraction of variation in the net carbon flux. The largest thousand negative GPP extremes during 1982?2011 (4.3% of the data) account for a decrease in photosynthetic carbon uptake of about 3.5?Pg?C?yr?1, with most events being attributable to water scarcity. The results imply that it is essential to understand the nature and causes of extremes to understand current and future GPP variability

Sustained biochemical response to oral antibiotics in pediatric PSC and ASC are correlated to changes in gut microbiota during therapy

Background and aim Concomitant presence of autoimmune hepatitis and primary sclerosing cholangitis (PSC) is labelled as autoimmune sclerosing cholangitis (ASC) in children. Based upon the possible implication of microbiota in the pathogenesis of PSC, oral antibiotics are increasingly being used as a novel therapeutic approach and shown to have benefit in PSC but their role in pediatric ASC is not well evaluated. We prospectively analysed the gut microflora before and after antibiotic therapy in children with ASC or PSC alone, and evaluated whether changes in gut microflora correlated with response to treatment. Methods Patients diagnosed with ASC or PSC on basis of biochemical, liver biopsy and radiology findings were included. They prospectively received metronidazole (MTZ) for 14 days as induction or rescue therapy. Antibiotics were administrated in addition to the standard treatment of UDCA for PSC patients and azathioprine, UDCA and/or steroids for ASC patients. Stool samples were collected before and after antibiotic therapy. DNA isolation, amplification and Illumina sequencing to profile the microbiota composition were performed using the bacterial 16s rRNA. The beta-diversity measured the dissimilarity between each paired stool samples. The outcome parameters to assess the efficacy of antibiotics were reduction liver enzymes and subsequently achievement of sustained biochemical remission. Results Seven children (4 ASC, 3 PSC) were included, of which 5 have a concomitant ulcerative colitis (UC). All patients showed a significant decrease in their AST (-44%, p<0.025), ALT (-56%, p<0.025) and GGT (-41%, p<0.025) under MTZ. Three children relapsed after stopping MTZ while the four others children showed a sustained biochemical remission (liver enzymes below 1.5 times upper limit of normal) after a median follow-up of 375 days. Among these four patients, three exhibited a wide different microbial composition before and after MTZ as expressed by the beta-diversity variation. On the contrary, the microbiota of patients who relapsed remained unchanged pre- and post-MTZ. Conclusions Our study suggests that oral antibiotic could be an effective treatment of ASC and PSC, especially those with a concomitant UC, and that intestinal microflora play a major role in these diseases as sustained biochemical remission is associated with wide changes in gut microbiota communities after taking antibiotics