Variability of BVOC emissions from a Mediterranean mixed forest in southern France with a focus on Quercus pubescens

International audienceWe aimed at quantifying biogenic volatile organic compound (BVOC) emissions in June from three Mediter-ranean species located at the O 3 HP site (southern France): Quercus pubescens, Acer monspessulanum and C. coggygria (for isoprene only). As Q. pubescens was shown to be the main BVOC emitter with isoprene representing ≈ 99 % of the carbon emitted as BVOC, we mainly focused on this species. C. coggygria was found to be a non-isoprene emitter (no other BVOCs were investigated). To fully understand both the canopy effect on Q. pubescens isoprene emissions and the inter-individual variability (tree to tree and within canopy), diurnal variations of isoprene were investigated from nine branches (seven branches located to the top of canopy at ≈ 4 m above ground level (a.g.l.), and two inside the canopy at ≈ 2 m a.g.l.). The Q. pubescens daily mean isoprene emission rate (ER d) fluctuated between 23 and 98 µgC g −1 DM h −1. Q. pubescens daily mean net assimilation (Pn) ranged between 5.4 and 13.8, and 2.8 and 6.4 µmol CO 2 m −2 s −1 for sunlit and shaded branches respectively. Both ER d and isoprene emission factors (Is), assessed according to Guenther et al. (1993) algorithm, varied by a factor of 4.3 among the sunlit branches. While sunlit branches ER d was clearly higher than for shaded branches, there was a non-significant variability of Is (59 to 77 µgC g −1 DM h −1). Diurnal variations of iso-prene emission rates (ERs) for sunlit branches were also investigated. ERs were detected at dawn 2 h after Pn became positive and were mostly exponentially dependent on Pn. Diurnal variations of ERs were not equally well described throughout the day by temperature (C T) and light (C L) parameters according to G93 algorithm. Temperature had more impact than photosynthetically active radiation (PAR) on the morning emissions increase, and ER was no longer correlated to C L × C T between solar noon (maximum ER) and mid-afternoon, possibly due to thermal stress of the plant. A comparison between measured and calculated emissions using two isoprene algorithms (G93 and MEGAN – Model of Emissions of Gases and Aerosols from Nature) highlighted the importance of isoprene emission factor Is value used, and some weakness in assessing isoprene emissions under Mediterranean climate conditions (drought) with current iso-prene models

Concentrations and fluxes of isoprene and oxygenated VOCs at a French Mediterranean oak forest

The CANOPEE project aims to better understand the biosphere–atmosphere exchanges of biogenic volatile organic compounds (BVOCs) in the case of Mediterranean ecosystems and the impact of in-canopy processes on the atmospheric chemical composition above the canopy. Based on an intensive field campaign, the objective of our work was to determine the chemical composition of the air inside a canopy as well as the net fluxes of reactive species between the canopy and the boundary layer. Measurements were carried out during spring 2012 at the field site of the Oak Observatory of the Observatoire de Haute Provence (O3HP) located in the southeast of France. The site is a forest ecosystem dominated by downy oak, Quercus pubescens Willd., a typical Mediterranean species which features large isoprene emission rates. Mixing ratios of isoprene, its degradation products methylvinylketone (MVK) and methacrolein (MACR) and several other oxygenated VOC (OxVOC) were measured above the canopy using an online proton transfer reaction mass spectrometer (PTR-MS), and fluxes were calculated by the disjunct eddy covariance approach. The O3HP site was found to be a very significant source of isoprene emissions, with daily maximum ambient concentrations ranging between 2–16 ppbv inside and 2–5 ppbv just above the top of the forest canopy. Significant isoprene fluxes were observed only during daytime, following diurnal cycles with midday net emission fluxes from the canopy ranging between 2.0 and 9.7 mg m−2 h1. Net isoprene normalized flux (at 30 °C, 1000 μmol quanta m−2 s−1) was estimated at 7.4 mg m−2 h−1. Evidence of direct emission of methanol was also found exhibiting maximum daytime fluxes ranging between 0.2 and 0.6 mg m−2 h−1, whereas flux values for monoterpenes and others OxVOC such as acetone and acetaldehyde were below the detection limit. The MVK+MACR-to-isoprene ratio provided useful information on the oxidation of isoprene, and is in agreement with recent findings proposing weak production yields of MVK and MACR, in remote forest regions where the NOx concentrations are low. In-canopy chemical oxidation of isoprene was found to be weak and did not seem to have a significant impact on isoprene concentrations and fluxes above the canopy

Proline and glycine betaine accumulation in two succulent halophytes under natural and experimental conditions

[EN] Proline (Pro) and glycine betaine (GB) contents were determined in two Mediterranean halophytes, Plantago crassifolia and Inula crithmoides, to assess their possible role in salt tolerance of both taxa. Plant material was collected in a littoral salt marsh under different environmental conditions, and from plants subjected to salt treatments in a growth chamber. Relative growth inhibition by NaCl indicated that I. crithmoides is more salt-tolerant than P. crassifolia, in agreement with the distribution of the two species in nature. Field and laboratory data confirmed GB as the major osmolyte responsible for osmotic adjustment in I. crithmoides, but with only a minor role if any as osmoprotectant in the salt tolerance of P. crassifolia. Under natural conditions, Pro contents were very low in both taxa, but increased to levels high enough to contribute significantly to osmotic balance when plants were artificially treated with 450 600mM NaCl higher salt concentrations than those they would normally encounter in their natural habitats. These data suggest that halophytes possess built-in mechanisms, such as accumulation of additional osmolytes, to rapidly adapt to increasing salinity levels in their natural ecosystems; for example, those expected to be caused by climate change in salt marshes in the Mediterranean region.This work was funded by a grant to O.V. from the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund. COST Action FA0901: "Putting Halophytes to work - From Genes to Ecosystems" supported M. N. Grigore for his stay in Valencia within the frame of a Short-Term Scientific Mission. A. Tifrea was funded by the Erasmus fellowship programme for her stay in Valencia to carry out her Master Thesis.Pardo-Domenech, L.; Tifrea, A.; Grigore, M.; Boscaiu, M.; Vicente, O. (2016). Proline and glycine betaine accumulation in two succulent halophytes under natural and experimental conditions. Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology. 150(5):904-915. https://doi.org/10.1080/11263504.2014.990943S904915150

Information needs of parents of children with congenital anomalies across Europe: a EUROlinkCAT survey.

BACKGROUND: Parents of children who have a congenital anomaly can experience significant worry about their child's health. Access to clear, helpful, and trustworthy information can provide a valuable source of support. In this study the aim was to explore the information needs of parents/carers of children with congenital anomalies across Europe. METHOD: A cross-sectional online survey was developed in nine languages to measure parents' information needs, including: (1) the 'helpfulness'/'trustworthiness' of information received from eight relevant sources, and (2) overall satisfaction with information received. Parents/carers of children (0-10 years) with cleft lip, spina bifida, congenital heart defect [CHD] requiring surgery, and/or Down syndrome were recruited online via relevant organisations in 10 European countries from March-July 2021. Quantitative analyses using multivariable logistic regressions were performed. RESULTS: One thousand seventy parents/carers of children with a cleft lip (n = 247), spina bifida (n = 118), CHD (n = 366), Down syndrome (n = 281), and Down syndrome with CHD (n = 58) were recruited in Poland (n = 476), the UK (n = 120), Germany (n = 97), the Netherlands/Belgium (n = 74), Croatia (n = 68), Italy (n = 59), other European countries (n = 92), and not specified/non-European countries (n = 84). Most participants were mothers (92%) and aged 31-40 years (71%). Participants were most likely to rate support groups (63%), patient organisations (60%), specialist doctors/nurses (58%), and social media (57%) as 'very helpful' information sources. 'Very trustworthy' ratings remained high for specialist doctors/nurses (61%), however, they declined for support groups (47%), patient organisations (48%), and social media (35%). Germany had the highest proportion of participants who were 'very satisfied' (44%, 95% CI = 34%-54%) with information, whereas this percentage was lowest in Croatia (11%, 95% CI = 3%-19%) and Poland (15%, 95% CI = 11%-18%). Parents of children with Down syndrome had significantly lower satisfaction ratings than parents of children with CHD; 13% (95% CI = 8%-18%) reported being 'very satisfied' compared to 28% (95% CI = 23%-33%) in the CHD group. CONCLUSIONS: Findings suggest that informal sources of information (e.g. support groups) are of value to parents, however, they are not deemed as trustworthy as specialist medical sources. Satisfaction ratings differed across countries and by anomaly, and were particularly low in Croatia and Poland, as well as for parents of children with Down syndrome, which warrants further investigation

Interview à propos de la publication au CRISP, en collaboration avec J. Nizet, d'un courrier hebdomadaire consacré aux professeurs de l'enseignement secondaire

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Les professeurs de l'enseignement secondaire: Leurs caractéristiques sociologiques; leur appartenance politique et syndicale

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Approche expérimentale de l'impact des oiseaux piscivores sur une pisciculture extensive littoral

Une étude quantitative de la prédation par des oiseaux piscivores, le Héron Cendré (Ardea cinerea) et le Grand Cormoran (Phalacrocorax carbo) a été réalisée dans un bassin (2 ha) situé dans un vaste ensemble de réservoirs à poissons (140 ha en eau saumâtre) du littoral atlantique. Deux enclos, l'un protégé de la prédation par des filets et des fils (0,3 ha), l'autre accessible aux oiseaux (0,9 ha), ont été empoissonnés avec des Mulets (Chelon labrosus et Liza ramada). L'observation régulière des oiseaux a permis de constater dans les jours suivant l'empoissonnement une concentration spectaculaire mais brève des prédateurs, hérons et cormorans se partageant respectivement les zones peu profondes et profondes de l'enclos non protégé. Le dénombrement des poissons après trois semaines d'expérimentation a montré un épuisement total du stock de poissons. Les caractéristiques essentielles de la prédation sont la rapidité d'intervention des piscivores et la faible part des prélèvements par le héron (3 % du stock initial), malgré un taux de succès élevé (nombre de prises/nombre d'attaques). La prédation par le cormoran n'a pu être dissociée de la mortalité indirectement due aux prédateurs. Cependant, il est vraisemblable que ce prédateur soit à l'origine d'une grande part de la mortalité correspondante, évaluée entre 64 et 97 % du stock initial. L'importance de cette prédation s'explique par la fréquentation et l'intensité de la pêche (nombre d'attaques par minute) plus élevées que chez le héron