Contribution of deep soil layers to the transpiration of a temperate deciduous forest: Implications for the modelling of productivity

Climate change is imposing drier atmospheric and edaphic conditions on temperate forests. Here, we investigated how deep soil (down to 300 cm) water extraction contributed to the provision of water in the Fontainebleau-Barbeau temperate oak forest over two years, including the 2018 record drought. Deep water provision was key to sustain canopy transpiration during drought, with layers below 150 cm contributing up to 60% of the transpired water in August 2018, despite their very low density of fine roots. We further showed that soil databases used to parameterize ecosystem models largely underestimated the amount of water extractable from the soil by trees, due to a considerable underestimation of the tree rooting depth. The consensus database established for France gave an estimate of 207 mm for the soil water holding capacity (SWHC) at Fontainebleau-Barbeau, when our estimate based on the analysis of soil water content measurements was 1.9 times as high, reaching 390 ± 17 mm. Running the CASTANEA forest model with the database-derived SWHC yielded a 185 gC m^-2 y^-1 average underestimation of annual gross primary productivity under current climate, reaching up to 687 ± 117 gC m^-2 y^-1 under climate change scenario RCP8.5. It is likely that the strong underestimation of SWHC that we show at our site is not a special case, and concerns a large number of forest sites. Thus, we argue for a generalisation of deep soil water content measurements in forests, in order to improve the estimation of SWHC and the simulation of the forest carbon cycle in the current context of climate change.

Ketamine antagonizes toxic action of anticholinesterase agents

Ketamine is an anaesthetic interacting with several neurotransmitters. Among others, ketamine exerts some cholinergic actions (ACh). This paper presents the results of studying the interaction of ketamine with ACh in two animal species. Atropine slightly increased the time of immobility produced by ketamine injections in rats. Meanwhile, neostigmine slightly decreased such immobility. Ketamine resulted similar in behavioral actions and shared some electroencephalographic (EEG) actions of scopolamine in cats. The most striking interaction consisted on an antagonism of ketamine on the action of anticholinesterase agents. In both species, ketamine blocked the EEG and the behavioral toxic effects of neostigmine and physostigmine. Notwithstanding, the anticholinesterase agents were unable in reducing the actions of ketamine. This partial cholinergic agonist action of ketamine support certain but limited use of the anesthetic against insecticidal anticholinesterase poisoning.