The fingerprint of the summer 2018 drought in Europe on ground-based atmospheric CO2 measurements

During the summer of 2018, a widespread drought developed over Northern and Central Europe. The increase in temperature and the reduction of soil moisture have influenced carbon dioxide (CO₂) exchange between the atmosphere and terrestrial ecosystems in various ways, such as a reduction of photosynthesis, changes in ecosystem respiration, or allowing more frequent fires. In this study, we characterize the resulting perturbation of the atmospheric CO₂ seasonal cycles. 2018 has a good coverage of European regions affected by drought, allowing the investigation of how ecosystem flux anomalies impacted spatial CO₂ gradients between stations. This density of stations is unprecedented compared to previous drought events in 2003 and 2015, particularly thanks to the deployment of the Integrated Carbon Observation System (ICOS) network of atmospheric greenhouse gas monitoring stations in recent years. Seasonal CO₂ cycles from 48 European stations were available for 2017 and 2018. Earlier data were retrieved for comparison from international databases or national networks. Here, we show that the usual summer minimum in CO₂ due to the surface carbon uptake was reduced by 1.4 ppm in 2018 for the 10 stations located in the area most affected by the temperature anomaly, mostly in Northern Europe. Notwithstanding, the CO₂ transition phases before and after July were slower in 2018 compared to 2017, suggesting an extension of the growing season, with either continued CO₂ uptake by photosynthesis and/or a reduction in respiration driven by the depletion of substrate for respiration inherited from the previous months due to the drought. For stations with sufficiently long time series, the CO₂ anomaly observed in 2018 was compared to previous European droughts in 2003 and 2015. Considering the areas most affected by the temperature anomalies, we found a higher CO₂ anomaly in 2003 (+3 ppm averaged over 4 sites), and a smaller anomaly in 2015 (+1 ppm averaged over 11 sites) compared to 2018. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.

[The system of blood vessels in the glandular and muscular stomach of the chicken (author's transl)]

The vascular system of the stomach of the chicken was investigated by means of corrosion preparations as well as by light- and electronmicroscopic methods. The main vessels form a) an Intermuscular Plexus the outer longitudinal and inner circular layers of the muscle wall in the glandular stomach and b) a Subserous Plexus in the muscular stomach. In the glandular stomach the Interglandular Parietal Arterial Plexus I, situated below the Lamina muscularis mucosae I arises from the arteries which pass through gaps in the muscle wall. This Plexus I produces another plexus, the Interglandular Arterial Plexus II, located on top of the Lamina muscularis mucosae I. Both arterial plexuses are accompanied by venous plexuses, which convey the blood into a Subglandular Venous Plexus. -The vessels of the muscular stomach provide the predominant supply of blood to the muscle wall. The mucous membrane of the muscular stomach is vascularized far less than the one in the glandular stomach. -The hemodynamic relationships of the vessels of the hen's stomach and the significance of the fine structure of the subepithelial capillaries and venules for the exchange of materials are discussed.

Ultrastrukturelle Lokalisation der Mg⁺⁺- und Ca⁺⁺-aktivierbaren Adenosintriphosphatase im Spinalganglion von Schaf und Ziege

Light and electron microscopic investigations on the Mg⁺⁺- and Ca⁺⁺-activated ATPase of sheep and goat dorsal root ganglion have been carried out. Reaction products occur on plasma membranes and interfaces between neurons and sheath cells, between adjacent sheath cells and on the surface of unmyelinated fibers. Cytoplasmic protrusions of ganglion cells and numerous surface increasing invaginations of sheath membranes form close connections between neurons and sheath cells.