{"id":9550,"date":"2025-11-19T16:34:35","date_gmt":"2025-11-19T15:34:35","guid":{"rendered":"https:\/\/www.imbe.fr\/?post_type=tribe_events&#038;p=9550"},"modified":"2025-11-26T15:30:44","modified_gmt":"2025-11-26T14:30:44","slug":"these-de-legros-thibaud-la-litiere-des-forets-mediterraneennes-comme-source-demission-de-composes-organiques-volatils-biogeniques-covb-dans-un-climat-plus-aride-quelles-consequences-atmospher","status":"publish","type":"tribe_events","link":"https:\/\/www.imbe.fr\/en\/evenement\/these-de-legros-thibaud-la-litiere-des-forets-mediterraneennes-comme-source-demission-de-composes-organiques-volatils-biogeniques-covb-dans-un-climat-plus-aride-quelles-consequences-atmospher\/","title":{"rendered":"Thesis by LEGROS Thibaud \u201cThe litter of Mediterranean forests as a source of Biogenic Volatile Organic Compounds (BVOC) emissions in a more arid climate: what are the atmospheric consequences on a regional scale?\u201d"},"content":{"rendered":"<p><strong>Mr. <\/strong><strong>LEGROS Thibaud,<\/strong> doctoral student at IMBE, team<a href=\"https:\/\/www.imbe.fr\/en\/recherche\/equipes-de-recherche\/ecosom-ecologie-fonctionnelle-des-systemes-socioecologiques-aux-molecules\/\"> Functional ecology: from socio-ecological systems to molecules<\/a>, <strong>will publicly defend his thesis on Wednesday 17 December 2025, at 2pm in the PONTE Amphitheatre, Campus Saint J\u00e9r\u00f4me.<\/strong><\/p>\n<p><strong>In front of a jury made up of :<\/strong><\/p>\n<ul>\n<li><strong>Dr Alexandre ARMENGAUD, <\/strong>Guest member, AtmoSud<\/li>\n<li><strong>Dr Karine SARTELET, <\/strong>rapporteur, CEREA, Ecole nationale des ponts et chauss\u00e9es<\/li>\n<li><strong>Dr Joan LLUSI\u00c0, <\/strong>Rapporteur, CREAF, Spain<\/li>\n<li><strong>Dr Raluca CIURARU, e<\/strong>xaminatrice, Universit\u00e9 Paris-Saclay, INRAE<\/li>\n<li><strong>Professor Philippe Cuny<\/strong>, Chairman of the jury, AMU-MIO<\/li>\n<li><strong>Professor Catherine Fernandez<\/strong>, thesis co-director, IMBE<\/li>\n<li><strong>Dr Elena Ormeno-Fuentes, <\/strong>PhD supervisor, IMBE<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p><strong>Summary of work:<\/strong><\/p>\n<p>Emissions of Biogenic Volatile Organic Compounds (BVOCs) from the canopy have been characterised since the 1980s and their contribution to the formation of O<sub>3<\/sub> emissions have been quantified from the regional scale (South PACA region) to the global scale. This contrasts with VOCB emissions from soils and their litter, which are rarely characterised, even in the Mediterranean region, which is heavily affected by O<sub>3 <\/sub>and that it represents a hot spot for climate change, which could have a rapid impact on VOCB flows. To fill this knowledge gap, this thesis has two parts. On the one hand, the experimental part aims to characterise the fluxes of VOCBs in soils covered with litter in two typical forest formations in the Mediterranean region: the deciduous forest of <em>Quercus pubescens <\/em>within the experimental platform <em>in natura<\/em> of the O<sub>3<\/sub>HP - where VOCBs were measured in real time by PTR-ToF-MS - and the mixed forest of <em>Pinus halepensis<\/em> and <em>Quercus ilex <\/em>within the site <em>in natura<\/em> Fontblanche, where VOCBs were studied <em>via<\/em> off-line GC-MS analyses. These fluxes were measured in late spring or summer under conditions of natural water stress (SN) and long-term amplified water stress (SA) respectively, <em>via <\/em>precipitation restriction measures implemented over the last 10 or 9 years respectively. Secondly, the modelling component was used to assess the current contribution of soils (covered in litter) from forests (deciduous and coniferous) in the Sud-PACA region, using the Tingey algorithm. These emissions were then compared both with the VOCB emissions in a drier future scenario and with the VOCBs emitted by the modelled canopy. <em>via<\/em> MEGAN. Finally, the formation of O<sub>3<\/sub> has been estimated <em>via<\/em> the CHIMERE model. The experimental component illustrates that the soil (litter cover) of the mixed forest is characterised by a high emission factor (emissions at 30\u00b0C) of VOCBs (184 \u00b5gC.m<sup>-2<\/sup>.h<sup>-1 <\/sup>on average) made up of monoterpenes and sesquiterpenes, mainly due to the participation of <em>P. halepensis<\/em> emissions. Deciduous forest, on the other hand, has a lower emission factor (22 \u00b5gC.m<sup>-2<\/sup>.h<sup>-1<\/sup> on average) of highly volatile compounds (acetone and acetaldehyde). In both cases, the total flux of VOCBs in soils decreases very sharply under AS conditions (84% at Fontblanche and 43% at O<sub>3<\/sub>HP). In terms of modelling, VOCB flows from forest soils represent, on the scale of the Sud-PACA region and during the summer of 2022, 26 tC.day.<sup>-1<\/sup> under SN and 7 tC.day<sup>-1<\/sup> under AS, leading to an increase of 4% and 2% (respectively) in O<sub>3<\/sub> on a regional scale.<\/p>\n<p>&nbsp;<\/p>","protected":false},"excerpt":{"rendered":"<p>Monsieur LEGROS Thibaud, doctorant \u00e0 l\u2019IMBE, \u00e9quipe Ecologie fonctionnelle : des syst\u00e8mes socio\u00e9cologiques aux mol\u00e9cules, soutiendra publiquement ses travaux de th\u00e8se le mercredi 17 d\u00e9cembre 2025, \u00e0 14h dans L\u2019Amphith\u00e9\u00e2tre [&hellip;]<\/p>\n","protected":false},"author":300,"featured_media":0,"template":"","meta":{"_acf_changed":false,"_tribe_events_status":"","_tribe_events_status_reason":"","footnotes":""},"tags":[],"tribe_events_cat":[30],"class_list":["post-9550","tribe_events","type-tribe_events","status-publish","hentry","tribe_events_cat-soutenance","cat_soutenance"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/tribe_events\/9550","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/tribe_events"}],"about":[{"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/types\/tribe_events"}],"author":[{"embeddable":true,"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/users\/300"}],"version-history":[{"count":3,"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/tribe_events\/9550\/revisions"}],"predecessor-version":[{"id":9579,"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/tribe_events\/9550\/revisions\/9579"}],"wp:attachment":[{"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/media?parent=9550"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/tags?post=9550"},{"taxonomy":"tribe_events_cat","embeddable":true,"href":"https:\/\/www.imbe.fr\/en\/wp-json\/wp\/v2\/tribe_events_cat?post=9550"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}