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L’îlot de chaleur urbain (ICU), qui caractérise le différentiel de température entre un environnement urbain et le milieu rural environnant, est un phénomène météorologique à fort enjeu. Plus de la moitié de la population mondiale vit en ville où elle cohabite avec une biodiversité particulièrement vulnérable. En contexte de changement climatique, les vagues de chaleur deviennent plus fréquentes, leur durée et leur intensité augmentent. La hausse des températures due au milieu urbain s’ajoute à l’élévation de la température globale et accroît la vulnérabilité des citadins au stress thermique. L’observation de la température de l’air est essentielle pour faire avancer la recherche sur l’ICU, améliorer les prévisions numériques du temps en milieu urbain et éclairer les acteurs de l’aménagement qui souhaitent déployer des dispositifs d’atténuation. Or l’installation de réseaux de mesure urbains denses est coûteuse et la plupart des villes n’ont pas accès à l’observation fine échelle sur leur territoire. L’objectif de cette thèse est de montrer l’apport de données opportunes issues de stations météorologiques amateurs et de véhicules connectés, omniprésents en ville. Une méthodologie statistique qui fusionne ces mesures opportunes permet de produire une analyse fine échelle de l’ICU. En s’appuyant sur les réseaux professionnels des villes laboratoires de Dijon et Rennes, nous avons analysé chacune des deux sources de données pour mieux comprendre les causes des erreurs de mesure. Même si les observations opportunes sont particulièrement sujettes aux erreurs, des traitements proposés dans cette thèse permettent de les nettoyer efficacement afin d’en tirer un signal de qualité. Un modèle bayésien hiérarchique inféré avec l’approche INLA-SPDE est ensuite développé pour spatialiser les mesures opportunes et ainsi obtenir des cartes de l’ICU à pas de temps horaire et résolution hectométrique. Les cartographies obtenues sur Dijon sont cohérentes avec le réseau de référence et la racine de l’erreur quadratique moyenne est inférieure à 1°C. Ces résultats ouvrent la voie à de nouvelles perspectives en terme de recherche, par exemple pour l’évaluation de simulations des modèles de ville, mais aussi pour la constitution d’observations spatialisées utilisables en post-traitement des sorties de la prévision numérique du temps. Les cartographies permettront aussi d’éclairer les acteurs de l’aménagement urbain au regard de la problématique de l’ICU.

Le biome boréal, emmagasinant d’importantes quantités de carbone en son sol et recouvrant une majorité du territoire alaskien, fennoscandien et russe, contribue grandement au système climatique. Toutefois, les variabilités climatiques et les propriétés de l’écosystème, notamment en ce qui a trait à la présence ou l’absence de pergélisol, complexifient la quantification de la variabilité des bilans de carbone du biome boréal, au sein duquel se retrouvent des écosystèmes forestiers, lentiques et de zones humides. Ces bilans de carbone sont grandement influencés par le début et la fin de la saison de croissance photosynthétique, étant à leur tour dépendants de plusieurs variables environnementales telles que la température de l’air et du sol, le contenu du sol en eau, les stades de développement de la végétation, etc. Cette recherche vise à quantifier l’impact de ces variabilités environnementales sur la variabilité des moments où se produisent le début et la fin de la saison de croissance photosynthétique, en distinguant les forêts boréales avec et sans pergélisol. La saison de croissance photosynthétique est caractérisée à partir de la productivité primaire brute dérivée de mesures covariance des turbulences provenant de 40 sites-années d’observation à travers la forêt boréale nord-américaine où l’épinette noire est l’espèce d’arbre dominante. Les variables environnementales considérées étaient les températures de l’air et du sol, les stades de développement de la végétation, le couvert nival, le rayonnement photosynthétiquement actif et le contenu du sol en eau. Le cadre statistique choisi incluait le calcul des coefficients de corrélations de Pearson, l’analyse des points communs et la modélisation par équations structurelles. Les résultats de cette étude montrent que la variabilité du début de la saison de croissance dans les sites sans pergélisol est contrôlée directement par la variabilité annuelle des stades de développement de la végétation ainsi que par le moment où survient le dégel du sol. Ce résultat souligne ainsi l’importance de l’accès à l’eau liquide du sol afin que la végétation initie la photosynthèse. Aucune variable environnementale ne pouvait significativement expliquer le contrôle du début de la photosynthèse au sein des sites avec pergélisol. À l’automne, le contenu du sol en eau ainsi que le début du couvert nival influencent directement la variabilité de la fin de la saison de croissance photosynthétique. Il est alors montré que la disponibilité de l’eau peut mener à une cessation plus hâtive de la photosynthèse à l’automne. L’effet de l’apparition du couvert nival est quant à lui opposé dans les sites avec et sans pergélisol. Son retard dans les sites sans pergélisol témoigne d’une température de l’air suffisamment élevée pour que les précipitations tombent sous forme liquide, prolongeant ainsi les activités photosynthétiques. Son retard dans les sites avec pergélisol signifie plutôt des précipitations neigeuses moindres, retardant ainsi l’apparition d’une couche isolante pour le sol, qui aurait pu allonger la saison de croissance photosynthétique. Cette étude contribue à clarifier les processus contrôlant le début et la fin de la saison de croissance photosynthétique et aidera à améliorer la compréhension des effets des changements climatiques sur la force du puits de carbone de la forêt boréale nord-américaine., The boreal forest, storing large amounts of carbon in its soil and covering a majority of the Alaskan, Canadian, Fennoscandian and Russian territory, is an integral part of the climate system. However, climatic variability and ecosystem properties, particularly with regards to the presence or absence of permafrost, limits our understanding of the carbon balance variability in the boreal biome, which comprises forest, lake and wetland ecosystems. The boreal carbon sink-source strength is greatly influenced by phenological events, including the start and end of the photosynthetic growing season, which are themselves dependent on several environmental variables such as air and soil temperature, soil water content, vegetation development stages, etc. This research aims to provide new insights on the influence of environmental variability on the variability in the timing of the photosynthetic growing season, by broadly distinguishing between boreal forests with and without permafrost. The photosynthetic growing season is characterized using gross primary productivity derived from eddy covariance measurements of net ecosystem carbon dioxide exchange. Data from 40 black spruce- dominated site-years of observation across the North American boreal forest are used. The considered environmental predictors were air and soil temperatures, vegetation development stages, snow cover, photosynthetically active radiation and soil water content. The statistical framework included the calculation of Pearson correlation coefficients, commonality analyses and structural equation modeling. This study shows that the variability in the start of the growing season in permafrost-free sites is directly controlled by the variability in vegetation development stage as well as by the thawing of seasonally frozen ground. This result thus emphasizes the importance of access to liquid soil water for the vegetation to initiate photosynthesis. No environmental variable could significantly explain photosynthesis recovery in sites with permafrost. In fall, the soil water content as well as the start of snow cover directly influence the variability in the end of the photosynthetic growing season. These results suggest that the availability of water can limit photosynthesis in the fall. The effect of snow cover is opposite in sites with and without permafrost. A delay in the appearance of continuous snow cover in sites without permafrost indicates that the air temperature is high enough for precipitation to fall in liquid form and for photosynthesis to continue. In contrast, its delay in sites with permafrost indicates less snowfall, thus delaying the appearance of an insulating layer for the soil, which could have lengthened the photosynthetic growing season. This study sheds light on the controls of the annual variation of the timing of the photosynthetic growing season and will help understanding of the effects of climate change on the strength of the North American boreal forest carbon sink.

International audience; The study focuses on the measurement methods used for the observation and quantitative characterization of the urban heat island in the Metz metropolitean urban area in northeastern France. The first is spatial remote sensing to characterize daytime land surface temperatures in order to spatialize areas of high heat release and conversely, those characterized by a certain coolness. The second method consists in carrying out measurements of the air temperature from a network of 28 meteorological stations fixed at 3 m from the ground, allowing continuous measurements. This network is completed by the method of mobile measurements by urban transects carried out by bicycle in order to apprehend more finely the spatial variability of the air temperature. Finally, the fourth method is airborne measurements by drone to measure surface temperatures at fine scale. The results obtained are useful for decision-making. They can be used for instance as a support to make concrete the adaptation to the climate change for the general public and to ccompany it to the change in behavior and practice of the places in period of strong heat; L’étude porte sur les méthodes de mesure utilisées pour l’observation et la caractérisation quantitative des champs de température de l’aire urbaine de Metz Métropole, dans le Nord-Est de la France. La première est la télédétection spatiale permettant de caractériser les températures de surface terrestres de jour afin de spatialiser les zones de fort dégagement de chaleur et a contrario, celles se caractérisant par une certaine fraîcheur. La deuxième méthode consiste à effectuer des mesures de la température de l’air à partir d’un réseau de 28 stations météorologiques fixées à 3 m du sol, permettant des mesures en continu. Ce réseau est complété par la méthode de mesures mobiles par transects urbains effectuées à vélo afin d’appréhender plus finement la variabilité spatiale de la température de l’air. Enfin, la quatrième méthode correspond à des mesures aéroportées par drone permettant de mesurer les températures de surface à échelle fine. Les résultats multi-échelles obtenus dans le cadre de ce travail apportent des données utiles à la décision. Elles pourront servir en outre de support pour rendre concrète l'adaptation au changement climatique pour le grand public et l’accompagner au changement en matière de comportement et de pratique des lieux en période de forte chaleur.

Bacterial panicle blight (BPB) caused by Burkholderia glumae is one of the main concerns for rice production in the Americas since bacterial infection can interfere with the grain-filling process and under severe conditions can result in high sterility. B. glumae has been detected in several rice-growing areas of Colombia and other countries of Central and Andean regions in Latin America, although evidence of its involvement in decreasing yield under these conditions is lacking. Analysis of different parameters in trials established in three rice-growing areas showed that, despite BPB presence, severity did not explain the sterility observed in fields. PCR tests for B. glumae confirmed low infection in all sites and genotypes, only 21.4% of the analyzed samples were positive for B. glumae. Climate parameters showed that Montería and Saldaña registered maximum temperature above 34°C, minimum temperature above 23°C, and Relative Humidity above 80%, conditions that favor the invasion model described for this pathogen in Asia. Our study found that in Colombia, minimum temperature above 23°C during 10 days after flowering is the condition that correlates with disease incidence. Therefore, this correlation, and the fact that Montería and Saldaña had a higher level of infected samples according to PCR tests, high minimum temperature, but not maximum temperature, seems to be determinant for B. glumae colonization under studied field conditions. This knowledge is a solid base line to design strategies for disease control, and is also a key element for breeders to develop strategies aimed to decrease the effect of B. glumae and high night-temperature on rice yield under tropical conditions.

International audience; This paper focuses on the measurement and mapping of the urban heat island (UHI) in the urban canopy layer within the Metz Metropole urban area between June and September 2019. The UHI was monitored using a network of 23 weather stations allowing continuous observations of the air temperature at 3 m above ground level. These observation sites were carefully selected so as to be representative of different types of environment (urban, suburban and periurban) and pavement typologies (asphalt impervious surfaces, vegetalized surfaces, bodies of water, etc.). The purpose is to evaluate the spatial and temporal properties of the summer UHI during this remarkably hot period, and to determine its intensity from the data continuously collected by the measurement network. The observation period is of particular interest as it is characterized by the occurrence of the two heat waves (June 25th-30th and July 21st-26th), offering the opportunity to better understand the thermal behavior of the urban fabric and the dynamics of the local UHI during hot extremes. The results obtained revealed an UHI of around 3°C on average in densely urbanized areas, reaching 7,1°C in a heat wave situation, which is in line with the predictive model of Oke (1973) based on the population-UHI relationship in Europe. However, a high presence of vegetation is likely to reduce its intensity and effects, unlike bodies of water, which do not seem to act as a cool sink at night.; Cet article s’intéresse à la mesure et à la cartographie de l’îlot de chaleur urbain (ICU) dans la couche de canopée urbaine au sein de l’aire urbaine de Metz Métropole entre juin et septembre 2019. L’ICU a été suivi à partir d’un réseau de 23 stations météorologiques fixes permettant d’observer en continu la température de l’air à 3 m du sol. Les sites d’observation ont été soigneusement sélectionnés de façon à être représentatifs de différents types d’environnement (urbain, suburbain et périurbain) et typologies de revêtement (surfaces imperméables bitumées, surfaces végétalisées, étendues d’eau, etc.). L’objectif est d’évaluer les propriétés spatiales et temporelles de l’ICU au cours de cette période remarquablement chaude, et de déterminer son intensité à partir des données relevées en continu par le réseau de mesure. La période d’observation est particulièrement intéressante dans la mesure où elle se caractérise par la survenue des deux séquences caniculaires (25-30 juin et 21-26 juillet), offrant la possibilité de mieux comprendre le comportement thermique du tissu urbain et la dynamique de l’ICU local lors d’extrêmes chauds. Les résultats obtenus ont permis de mettre en évidence un ICU de l’ordre de 3°C en moyenne au sein des zones densément urbanisées, pouvant atteindre 7,1°C en situation caniculaire ce qui est conforme au modèle prédictif de Oke (1973) fondé sur la relation population-ICU en Europe. Une importante présence de végétation est toutefois susceptible de réduire son intensité et ses effets contrairement aux étendues d’eau qui, la nuit, ne semblent pas jouer le rôle de puits de fraîcheur.

Coffee leaf rust is a polycyclic disease that causes severe epidemics impacting yield over several years. For this reason, since the 1960s, more than 20 models have been developed to predict different indicators of the disease's development and help manage it. In existing models, standardized periods of influence of the meteorological predictors of the disease are determined a priori, based on strong assumptions. However, the appearance of a symptom or sign can be influenced by complex combinations of meteorological variables acting at different times and for different durations. In our study, we monitored a total of 5400 coffee leaves during a year and a half, in different agroforestry systems, in order to detect the onset dates of the disease symptoms, such as lesion emergence, and signs, such as sporulation and infectious area increase. In these agroforestry systems, we also recorded microclimate. We statistically identified the complex combinations of microclimatic variables responsible for changes in lesion status to construct three models predicting lesion emergence probability, lesion sporulation probability and growth of its infectious area. Our method allowed the identification of different microclimatic variables that fit well with the knowledge about the coffee leaf rust biology. Minimum air temperature from 20 to 18 days before a lesion emergence explained the status change from healthy to emergence of visible lesion, possibly because the short germination phase is stimulated by low temperatures. We also found a unimodal effect of rainfall over a period of 10 days, 33 days before lesion emergence, with a maximum at 10 mm. Below this threshold, uredospore dispersal is efficient, increasing the lesion appearance probability; above this threshold, wash-off effects on uredospores probably occurs, decreasing the probability of lesion emergence. In addition, we identified microclimatic variables whose influence on coffee leaf rust had not been described before. These variables are likely to be involved in the internal development phases of the disease in the coffee leaves: (1) unimodal effects of maximum air temperature in different periods on sporulation and infectious area growth (2) positive and unimodal effects of rainfall in different periods on sporulation and (3) a negative effect of leaf thermal amplitude in different periods on lesion emergence, sporulation and infectious area growth. Although these models do not provide predictors of the level of disease attack, such as incidence, they provide valuable information for warning systems and for mechanistic model development. These models could also be used to forecast risks of infection, sporulation and infectious area growth and help optimize treatment recommendations.

U nderstanding how photosynthesis responds to warming has been a focus in plant research in recent decades, and most of the existing knowledge comes from leaf-scale measurements 1-4. Most leaf-scale temperature response curves show that photosyn-thetic capacity increases with temperature up to an optimum temperature (T opt leaf), which typically occurs in the 30-40 °C temperature range 5,6. Above this optimum temperature, foliar photosynthetic capacity sharply declines as electron-transport and Rubisco enzy-matic capacities become impaired 7. Field et al. 8 suggested that ecosystem-scale optimum temperature T opt eco may differ from T opt leaf. At the ecosystem scale, elevated air temperatures do limit canopy photosynthesis by processes other than leaf carboxylation rates. For instance, elevated air temperatures may accelerate leaf ageing and increase leaf thickness (phenology; for example, ref. 9) and control stomatal closure because a higher temperature usually comes with a higher vapour pressure deficit (VPD) 10. In a more extreme case, warming-induced water stress could suppress canopy photosyn-thesis through partial hydraulic failure (hydraulics) by cavitation (for example, ref. 11). Empirical leaf-scale photosynthesis-temperature relationships 12 have been directly incorporated into global ecosystem models, with variants to account for acclimation, that is, a temporal adjustment of optimum photosynthetic temperature to air temperature during growth 5,13,14. This direct scaling of temperature responses from leaves to ecosystems partly determines model projections of gross primary productivity (GPP) and CO 2 uptake by terrestrial ecosystems in climatic scenarios. Verifying the existence of T opt eco in real-world ecosystems, defining its spatial distribution across and within biomes, and understanding the relationships between T opt eco , prevailing air temperature and T opt leaf are important for evaluating models and understanding the impacts of various climatic warming targets on ecosystem productivity. In this study, we formulate and test the following hypotheses: (1) T opt eco is higher for biomes when air temperature during growth is warmer, (2) T opt eco is lower than T opt leaf for any given ecosystem because the limitations mentioned earlier of stomatal conductance and phenology emerge before temperature begins to impair foliar pho-tosynthetic capacity, and (3) tropical forests already operate near a high T opt eco , above which canopy photosynthesis may decrease with even moderate air temperature warming 15,16. Here, we defined T opt eco as the daytime air temperature at which GPP is highest over a period of several years, and thus T opt eco can be empirically determined from productivity observations and proxies (see Methods). Results and discussion We first applied this approach on time series of daily GPP derived from CO 2 flux measurements at 153 globally distributed eddy cova-riance sites and found that a robust estimate of T opt eco could be derived The global distribution of the optimum air temperature for ecosystem-level gross primary productivity (T opt eco) is poorly understood , despite its importance for ecosystem carbon uptake under future warming. We provide empirical evidence for the existence of such an optimum, using measurements of in situ eddy covariance and satellite-derived proxies, and report its global distribution. T opt eco is consistently lower than the physiological optimum temperature of leaf-level photosynthetic capacity, which typically exceeds 30 °C. The global average T opt eco is estimated to be 23 ± 6 °C, with warmer regions having higher T opt eco values than colder regions. In tropical forests in particular, T opt eco is close to growing-season air temperature and is projected to fall below it under all scenarios of future climate, suggesting a limited safe operating space for these ecosystems under future warming.

In a number of tropical countries, the expansion of cassava processing is tied to the development of small-scale, energy-efficient pneumatic dryers used to dry flour and starch. To facilitate this development, in this study a model of the pneumatic drying of starch particles was developed, to be fitted to measurements taken from large cassava processing factories. After that, numerical simulations were performed to analyse the effects of geometry and operating conditions on the energy efficiency and pipe length required to dry the product. The results clarified the influence of processing capacity, air inlet conditions and starch particle size, emphasizing that air velocity, as well as the dilution of the starch, should be minimised. In light of the findings described here, we offer guidelines for the design of efficient small-capacity flash dryers.

Conifer trees possess a typical anatomical tree-ring structure characterized by a transition from large and thin-walled earlywood tracheids to narrow and thick-walled latewood tracheids. However, little is known on how this characteristic structure is maintained across contrasting environmental conditions, due to its crucial role to ensure sap ascent and mechanical support. In this study, we monitored weekly wood cell formation for up to 7 years in two temperate conifer species (i.e., Picea abies (L.) Karst and Larix decidua Mill.) across an 8°C thermal gradient from 800 to 2,200 m a.s.l. in central Europe to investigate the impact of air temperature on rate and duration of wood cell formation. Results indicated that towards colder sites, forming tracheids compensate a decreased rate of differentiation (cell enlarging and wall thickening) by an extended duration, except for the last cells of the latewood in the wall-thickening phase. This compensation allows conifer trees to mitigate the influence of air temperature on the final tree-ring structure, with important implications for the functioning and resilience of the xylem to varying environmental conditions. The disappearing compensation in the thickening latewood cells might also explain the higher climatic sensitivity usually found in maximum latewood density.

International audience

No presente artigo se tem por objetivo analisar a intensidade e a distribuição de ilhas de calor em Assis, Cândido Mota, Maracaí e Tarumã, cidades de médio e pequeno porte do interior do estado de São Paulo/Brasil. Para tanto, a técnica utilizada foi a dos transectos móveis, que consiste nos registros de temperatura do ar com sensores acoplados na lateral de veículos em baixa velocidade de deslocamento nos ambientes intraurbanos e entornos rurais próximos às áreas construídas. Tais registros ocorreram nos dias 21 e 22 de maio, 3 a 6 de junho e 16 a 20 de julho de 2013, às 06h e 21h, de maneira simultânea, nas quatro cidades. Os resultados apontaram que Assis, a maior cidade do estudo, apresentou a mais elevada temperatura absoluta (21,3°C às 06h e 24,8°C às 21h) e a maior intensidade de ilha de calor se deu em Cândido Mota, com 6,7°C às 21h, em 17 de julho de 2013. Dans cet article nous analysons l’intensité et la distribution des îlots de chaleur urbains (ICU) à Assis, Cândido Mota, Maracaí et Tarumã, villes de petite et moyenne taille de la province de Sao Paulo, Sud-Est du Brésil. Pour cela, la technique de transect mobile a été utilisée. Elle consiste à enregistrer la température de l’air par capteurs placés dans un abri et l’ensemble est installé sur un mat fixé à une voiture en basse vitesse en passant par des environnements intra-urbains et entourages ruraux. Ces données ont été enregistrées à 6h et 21h des journées de 21 et 22 mai, 3 à 6 juin et 16 à 20 juillet 2013, simultanément sur les quatre villes. Les résultats montrent qu’Assis (la plus grande ville) a présenté la température absolue la plus élevée (21,3°C à 06h et 24,8°C à 21h) et que l’intensité d’ICU la plus importante a été enregistrée à Cândido Mota avec la valeur de 6,7°C à 21h au 17 juillet 2013. In the present article, we aim to analyze the intensity and distribution of heat islands in Assis, Cândido Mota, Maracaí and Tarumã, cities of medium and small size of the countryside in the state of São Paulo, Brazil. Therefore, the technique used was the mobile transects, which consists of recording air temperatures with sensors fitted on the side of vehicles in low travel speed, in the interurban environments and rural surroundings, near built-up areas. Such records took place on the 21st and 22nd of May, on the 3rd to the 6th of June and on the 16th to the 20th of July 2013, at 6 a.m. and 9 p.m., simultaneously, in the four cities. The results showed that Assis, the largest city in the study, had the highest absolute temperature (21.3°C at 06 a.m. and 24.8°C at 9 p.m.) and the highest heat island intensity was observed in Cândido Mota, with 6.7°C at 9 p.m., on July 17th 2013.

In this century, the world has already witnessed the biggest increasein its population in human history, which led to the increase of theuse of the land and shrinking green areas. The main concern of thepresent thesis is the city which is characterized by higher nighttimetemperature compared to rural areas. This phenomenon is known asan urban heat island (UHI). UHI leads to degraded comfortconditions both outdoor and indoor, and as a result, higher energyconsumption for cooling.One of the main reasons for the UHI is the materials used forbuilding envelope and urban areas. Many attempts have been madeto avoid UHI by using a new type of materials such as usingmaterials with high solar reflectance. In addition, these types ofmaterials help minimize energy consumption if used on an urbanscale. In our research, we address the building envelope designwith respect to its main types of construction materials as well as itslayer design and its shape to mitigate the urban heat island andachieve energy consumption reduction. The work is applied on oneof the important residential complexes in Mosul city – Iraq, which willbe constructed in many cities in Iraq. The weather of the Mosul cityis characterized by hot semi-arid climate. In summer, the climate isdry and extremely hot, whereas it is very cold and the temperaturesare down to below zero in winter. The main objective of this researchis to propose an appropriate building envelope design and designstrategy which provides high thermal performance regarding theexterior and interior surface temperature, high-level of indoor thermalcomfort with minimum energy needed, reduce the air temperaturedifference between the city and its surrounding rural area. It tacklessome important questions that are related to the case study: What isthe relation between the building envelope design and the followingaspects: 1. The external surfaces temperature of buildings andurban surfaces which lead to raise the air temperature, and finallycontribute to the UHI phenomenon, 2. The indoor surfacestemperature of buildings which influence the indoor thermal comfortand the energy needed to maintain this level of comfort?To answer the research questions, simulations have been achievedby using Solene-microclimat. From simulation results, it is shownthat it is possible to find different combinations of materials, formsand surface coatings to both to reduce the interior and exteriorsurfaces temperature and consequently, maintain indoor andoutdoor thermal comfort. We also show that the strategy can bedifferent depending on the surface exposure to the sun and theinteraction between surfaces. We propose a methodology to find thebest combination depending on the case study.; Dans notre siècle, le monde a déjà connu la plus grandeaugmentation de sa population à travers l'histoire de l'humanité. Cephénomène conduit à une utilisation accrue de la terre agricole pourl’urbanisation et à réduire les zones vertes en ville. Les villesconnaissent des températures plus élevées la nuit que les zonesrurales environnantes. Ce phénomène est connu sous le nom d'îlotde chaleur urbain (ICU). Il contribue à la dégradation du confortthermique en ville à l’éxtérieur et dans les bâtiments et àl’augmentation des consommations énergétiques pour lerefraichissement. L'une des principales raisons de ICU est liée auxmatériaux de construction pour la construction l'enveloppe desbâtiments et pour les surfaces urbaines. De nombreuses étudesportent sur le développement des revêtements pour réduire l’ICU.Cette thèse traite de la conception de l'enveloppe du bâtiment, etprincipalement ses types de matériaux de construction et sa formepour lutter contre l'îlot de la chaleur urbain et réduire laconsommation d'énergie des bâtiment. Elle est appliquée à l'un desprincipaux complexes résidentiels à Mossoul, qui sera construit dansde nombreuses villes en Irak. La ville de Mossoul se caractérise parun climat semi-aride et chaud. En été, il est sec et extrêmementchaud, tandis qu’en hiver il fait très froid et les températures sont audessous de zéro. L'objectif principal de cette recherche est montrerqu’une conception d’enveloppe du bâtiment appropriée permetd’atteindre de bonnes performances thermiques à l'égard de latempérature extérieure et intérieure de la surface Cette rechercheaborde les questions suivantes, quel est le lien entre la conceptionde l’enveloppe bâtie et : 1/ la température des surfaces extérieuresdes bâtiments et des surfaces urbaines qui entraîne l’augmentationde la température de l'air et donc la formation du phénomène d’ICU,2/ la température des surfaces intérieures des bâtiments quiinfluence le confort thermique intérieur et la quantité d'énergienécessaire pour maintenir ce niveau de confort? Pour répondre, dessimulations ont été réalisées en utilisant solene-microclimate.D'après les résultats des simulations, il est démontré qu’il estpossible d’établir des combinaisons de matériaux, formes desurfaces et al.bédo permettant d’améliorer à la fois les conditions deconfort thermique intérieures et extérieures. Ces combinaisonspeuvent différer en fonction de l’exposition solaire des surfaces et deleurs interactions. Nous proposons ainsi une méthodologie deconception adaptée aux phases de conception et qui a étéappliquée au cas d’étude.

In this century, the world has already witnessed the biggest increasein its population in human history, which led to the increase of theuse of the land and shrinking green areas. The main concern of thepresent thesis is the city which is characterized by higher nighttimetemperature compared to rural areas. This phenomenon is known asan urban heat island (UHI). UHI leads to degraded comfortconditions both outdoor and indoor, and as a result, higher energyconsumption for cooling.One of the main reasons for the UHI is the materials used forbuilding envelope and urban areas. Many attempts have been madeto avoid UHI by using a new type of materials such as usingmaterials with high solar reflectance. In addition, these types ofmaterials help minimize energy consumption if used on an urbanscale. In our research, we address the building envelope designwith respect to its main types of construction materials as well as itslayer design and its shape to mitigate the urban heat island andachieve energy consumption reduction. The work is applied on oneof the important residential complexes in Mosul city – Iraq, which willbe constructed in many cities in Iraq. The weather of the Mosul cityis characterized by hot semi-arid climate. In summer, the climate isdry and extremely hot, whereas it is very cold and the temperaturesare down to below zero in winter. The main objective of this researchis to propose an appropriate building envelope design and designstrategy which provides high thermal performance regarding theexterior and interior surface temperature, high-level of indoor thermalcomfort with minimum energy needed, reduce the air temperaturedifference between the city and its surrounding rural area. It tacklessome important questions that are related to the case study: What isthe relation between the building envelope design and the followingaspects: 1. The external surfaces temperature of buildings andurban surfaces which lead to raise the air temperature, and finallycontribute to the UHI phenomenon, 2. The indoor surfacestemperature of buildings which influence the indoor thermal comfortand the energy needed to maintain this level of comfort?To answer the research questions, simulations have been achievedby using Solene-microclimat. From simulation results, it is shownthat it is possible to find different combinations of materials, formsand surface coatings to both to reduce the interior and exteriorsurfaces temperature and consequently, maintain indoor andoutdoor thermal comfort. We also show that the strategy can bedifferent depending on the surface exposure to the sun and theinteraction between surfaces. We propose a methodology to find thebest combination depending on the case study.; Dans notre siècle, le monde a déjà connu la plus grandeaugmentation de sa population à travers l'histoire de l'humanité. Cephénomène conduit à une utilisation accrue de la terre agricole pourl’urbanisation et à réduire les zones vertes en ville. Les villesconnaissent des températures plus élevées la nuit que les zonesrurales environnantes. Ce phénomène est connu sous le nom d'îlotde chaleur urbain (ICU). Il contribue à la dégradation du confortthermique en ville à l’éxtérieur et dans les bâtiments et àl’augmentation des consommations énergétiques pour lerefraichissement. L'une des principales raisons de ICU est liée auxmatériaux de construction pour la construction l'enveloppe desbâtiments et pour les surfaces urbaines. De nombreuses étudesportent sur le développement des revêtements pour réduire l’ICU.Cette thèse traite de la conception de l'enveloppe du bâtiment, etprincipalement ses types de matériaux de construction et sa formepour lutter contre l'îlot de la chaleur urbain et réduire laconsommation d'énergie des bâtiment. Elle est appliquée à l'un desprincipaux complexes résidentiels à Mossoul, qui sera construit dansde nombreuses villes en Irak. La ville de Mossoul se caractérise parun climat semi-aride et chaud. En été, il est sec et extrêmementchaud, tandis qu’en hiver il fait très froid et les températures sont audessous de zéro. L'objectif principal de cette recherche est montrerqu’une conception d’enveloppe du bâtiment appropriée permetd’atteindre de bonnes performances thermiques à l'égard de latempérature extérieure et intérieure de la surface Cette rechercheaborde les questions suivantes, quel est le lien entre la conceptionde l’enveloppe bâtie et : 1/ la température des surfaces extérieuresdes bâtiments et des surfaces urbaines qui entraîne l’augmentationde la température de l'air et donc la formation du phénomène d’ICU,2/ la température des surfaces intérieures des bâtiments quiinfluence le confort thermique intérieur et la quantité d'énergienécessaire pour maintenir ce niveau de confort? Pour répondre, dessimulations ont été réalisées en utilisant solene-microclimate.D'après les résultats des simulations, il est démontré qu’il estpossible d’établir des combinaisons de matériaux, formes desurfaces et al.bédo permettant d’améliorer à la fois les conditions deconfort thermique intérieures et extérieures. Ces combinaisonspeuvent différer en fonction de l’exposition solaire des surfaces et deleurs interactions. Nous proposons ainsi une méthodologie deconception adaptée aux phases de conception et qui a étéappliquée au cas d’étude.

Cocoa beans (Theobroma cocoa L.) are the main components for chocolate manufacturing. The beans must be correctly fermented at first. Traditional process to perform the first fermentation (lactic fermentation) often consists in confining cacao beans using banana leaves or a fermentation basket, both of them leading to a poor product thermal insulation and to an inability to mix the product. Box fermenter reduces this loss by using a wood with large thickness (e>3cm), but mixing to homogenize the product is still hard to perform. Automatic fermenters are not rentable for most of producers. Heat (T>45°C) and acidity produced during the fermentation by microbiology activity of yeasts and bacteria are enabling the emergence of potential flavor and taste of future chocolate. In this study, a cylindro-rotative fermenter (FCR-V1) has been built and coconut fibers were used in its structure to confine heat. An axis of rotation (360°) has been integrated to facilitate the turning and homogenization of beans in the fermenter. This axis permits to put fermenter in a vertical position during the anaerobic alcoholic phase of fermentation, and horizontally during acetic phase to take advantage of the mid height filling. For circulation of air flow during turning in acetic phase, two woven rattan with grid have been made, one for the top and second for the bottom of the fermenter. In order to reduce air flow during acetic phase, two airtight covers are put on each grid cover. The efficiency of the turning by this kind of rotation, coupled with homogenization of the temperature, caused by the horizontal position in the acetic phase of the fermenter, contribute to having a good proportion of well-fermented beans (83.23%). In addition, beans’pH values ranged between 4.5 and 5.5. These values are ideal for enzymatic activity in the production of the aromatic compounds inside beans. The regularity of mass loss during all fermentation makes it possible to predict the drying surface corresponding to the amount being fermented., {"references":["L. De Vuyst and S. Weckx, \"The cocoa bean fermentation process: from ecosystem analysis to starter culture development,\" J. Appl. Microbiol., 2016.","D. H. Ouattara, H. G. Ouattara, B. G. Goualie, L. M. Kouame, and S. L. Niamke, \"Biochemical and functional properties of lactic acid bacteria isolated from Ivorian cocoa fermenting beans,\" J. Appl. Biosci., vol. 77, pp. 6489–6499, 2014.","M. Barel, Qualité du cacao L'impact du traitement post-récolte. quae, 2013.","R. F. Schwan and A. E. Wheals, \"The microbiology of cocoa fermentation and its role in chocolate quality,\" Crit. Rev. Food Sci. Nutr., vol. 44, no. 4, pp. 205–221, 2004.","P. Tissot, \"La fermentation du Cacao.,\" Rev. Bot. Appliquée Agric. Colon, vol. 16, no. 176, pp. 264–276, 1936.","S. S. Thompson, K. B. Miller, and A. S. Lopez, \"Cocoa and coffee,\" Food Microbiol.Fundam. Front., vol. 3, 2001.","M. Barel, \"La fermentation du cacao: le moyen de l'apprécier et de la maitriser,\" Ind. Aliment. Agric., vol. 114, no. 4, pp. 211–214, 1997.","E. Afoakwa, J. Kongor, J. Takrama, A. Budu, and others, \"Changes in nib acidification and biochemical composition during fermentation of pulp pre-conditioned cocoa (Theobroma cacao) beans.,\" Int. Food Res. J., vol. 20, no. 4, pp. 1843–1853, 2013.","B. Biehl, J. Voigt, H. Heinrichs, V. Senjuk, and G. Bytof, \"pH-dependent enzymatic formation of oligopeptides and amino acids, the aroma precursors in raw cocoa beans,\" in XIth international cocoa research conference. Cocoa Producers Alliance: Yamassoukro, Ivory Coast, 1993, pp. 717–722.\n[10]\tB. Biehl, E. Brunner, D. Passern, V. C. Quesnel, and D. Adomako, \"Acidification, proteolysis and flavour potential in fermenting cocoa beans,\" J. Sci. Food Agric., vol. 36, no. 7, pp. 583–598, 1985.\n[11]\tJ. Vincent, \"Influence de différents traitements technologiques sur la fermentation du cacao et le goût du chocolat,\" Cafe Cacao, vol. 14, pp. 303–322, 1970.\n[12]\tS. T. Guehi, S. Dabonne, L. Ban-Koffi, D. K. Kedjebo, and G. I. B. Zahouli, \"Effect of turning beans and fermentation method on the acidity and physical quality of raw cocoa beans,\" Adv. J. Food Sci. Technol., vol. 2, no. 3, pp. 163–171, 2010.\n[13]\tJ. Grimaldi, \"owu,\" Café Cacao Thé, vol. 22, pp. 303–316, 1978.\n[14]\tD. S. Nielsen, \"The microbiology of Ghanaian cocoa fermentations,\" Københavns Universitet'Københavns Universitet', LUKKET: 2012 Det Biovidenskabelige Fakultet for Fødevarer, Veterin\\a ermedicin og NaturressourcerFaculty of Life Sciences, LUKKET: 2012 Institut for FødevarevidenskabDepartment of Food Science, 2012 Institut for Fødevarevidenskab, 2012 FødevaremikrobiologiDepartment of Food Science, Food Microbiology, 2006.\n[15]\tM. Barel, \"Traitement du cacao par fermenteur et séchoir intégrés,\" Plant. Rech. Dév., vol. 2, no. 5, pp. 35–42, 1995.\n[16]\tJean Braudeau, \"Etude Scientifique:le Cacaoyer,\" 1973.\n[17]\tL. Bankoff, G. Ouattara, T. Karou, S. T. Guehi, J. Nemlin, and J. Diopoh, \"Impacts de la fermentation du cacao sur la croissance de la flore microbienne et la qualite des feves marchandes,\" Agron. Afr., vol. 25, no. 2, pp. 159–170, 2014.\n[18]\tG. V. de Melo Pereira, K. T. Magalhães, E. G. de Almeida, I. da Silva Coelho, and R. F. Schwan, \"Spontaneous cocoa bean fermentation carried out in a novel-design stainless steel tank: Influence on the dynamics of microbial populations and physical–chemical properties,\" Int. J. Food Microbiol., vol. 161, no. 2, pp. 121–133, 2013.\n[19]\tM. Apriyanto, E. Harmayani, and others, \"Study on effect of fermentation to the quality parameter of cocoa bean in Indonesia,\" Asian J. Dairy Food Res., vol. 35, no. 2, pp. 160–163, 2016.\n[20]\tR. U. Hatmi, M. Kobarsih, and N. Cahyaningrum, \"Fungi level analysis of cocoa beans based on fermentation box type and duration,\" Procedia Food Sci., vol. 3, pp. 371–382, 2015.\n[21]\tS. Hencke, \"Utilisation alimentaire des levures,\" 2000.\n[22]\tA. Boulal, Z. Benbrahim, B. Benali, and S. Ladjel, \"Etude comparative de rendement de la production déthanol de deux variétés de dattes communes de faible valeur commerciale (Tinaceur et Aghmou) de Sud–Ouest de lAlgérie,\" Rev. Energ. Renouvelables, vol. 16, no. 3, pp. 539–550, 2013.\n[23]\tW. Albertin et al., \"Fermentation rate, population size, CO2 flux and quantitative proteomics: a multi-level approach applied to alcoholic fermentation in Saccharomyces cerevisiae,\" in Oeno2011: Actes de colloques du 9e symposium international d'oenologie de Bordeaux, 2012, p. 382.\n[24]\tJ. Wollgast and E. Anklam, \"Review on polyphenols in Theobroma cacao: changes in composition during the manufacture of chocolate and methodology for identification and quantification,\" Food Res. Int., vol. 33, no. 6, pp. 423–447, 2000."]}

International audience; This paper focuses on the measurement and mapping of the urban heat island (UHI) in the urban canopy layer within the Metz Metropole urban area between June and September 2019. The UHI was monitored using a network of 23 weather stations allowing continuous observations of the air temperature at 3 m above ground level. These observation sites were carefully selected so as to be representative of different types of environment (urban, suburban and periurban) and pavement typologies (asphalt impervious surfaces, vegetalized surfaces, bodies of water, etc.). The purpose is to evaluate the spatial and temporal properties of the summer UHI during this remarkably hot period, and to determine its intensity from the data continuously collected by the measurement network. The observation period is of particular interest as it is characterized by the occurrence of the two heat waves (June 25th-30th and July 21st-26th), offering the opportunity to better understand the thermal behavior of the urban fabric and the dynamics of the local UHI during hot extremes. The results obtained revealed an UHI of around 3°C on average in densely urbanized areas, reaching 7,1°C in a heat wave situation, which is in line with the predictive model of Oke (1973) based on the population-UHI relationship in Europe. However, a high presence of vegetation is likely to reduce its intensity and effects, unlike bodies of water, which do not seem to act as a cool sink at night.; Cet article s’intéresse à la mesure et à la cartographie de l’îlot de chaleur urbain (ICU) dans la couche de canopée urbaine au sein de l’aire urbaine de Metz Métropole entre juin et septembre 2019. L’ICU a été suivi à partir d’un réseau de 23 stations météorologiques fixes permettant d’observer en continu la température de l’air à 3 m du sol. Les sites d’observation ont été soigneusement sélectionnés de façon à être représentatifs de différents types d’environnement (urbain, suburbain et périurbain) et typologies de revêtement (surfaces imperméables bitumées, surfaces végétalisées, étendues d’eau, etc.). L’objectif est d’évaluer les propriétés spatiales et temporelles de l’ICU au cours de cette période remarquablement chaude, et de déterminer son intensité à partir des données relevées en continu par le réseau de mesure. La période d’observation est particulièrement intéressante dans la mesure où elle se caractérise par la survenue des deux séquences caniculaires (25-30 juin et 21-26 juillet), offrant la possibilité de mieux comprendre le comportement thermique du tissu urbain et la dynamique de l’ICU local lors d’extrêmes chauds. Les résultats obtenus ont permis de mettre en évidence un ICU de l’ordre de 3°C en moyenne au sein des zones densément urbanisées, pouvant atteindre 7,1°C en situation caniculaire ce qui est conforme au modèle prédictif de Oke (1973) fondé sur la relation population-ICU en Europe. Une importante présence de végétation est toutefois susceptible de réduire son intensité et ses effets contrairement aux étendues d’eau qui, la nuit, ne semblent pas jouer le rôle de puits de fraîcheur.

Agrivoltaic systems are mixed systems that associate, on the same land area at the same time, food crops and solar photovoltaic panels (PVPs). The aim of the present study is to assess whether the growth rate of crops is affected in the specific shade of PVPs. Changes in air, ground and crop temperature can be suspected due to the reduction of incident radiation below the photovoltaic shelter. Soil temperature (5 cm and 25 cm depth), air temperature and humidity, wind speed as well as incident radiations were recorded at hourly time steps in the full sun treatment and in two agrivoltaic systems with different densities of PVPs during three weather seasons (winter, spring and summer). In addition, crop temperatures were monitored on short cycle crops (lettuce and cucumber) and a long cycle crop (durum wheat). The number of leaves was also assessed periodically on the vegetable crops. Mean daily air temperature and humidity were similar in the full sun treatments and in the shaded situations, whatever the climatic season. On the contrary, mean daily soil temperature significantly decreased below the PVPs compared to the full sun treatment. The hourly pattern of crop temperature during daytime (24 h) was affected in the shade. In this experiment, the ratio between crop temperature and incident radiation was higher below the PVPs in the morning. This could be due to a reduction of sensible heat losses by the plants (absence of dew deposit in the early morning or reduced transpiration) in the shade compared to the full sun treatment. However, mean daily crop temperature was found not to change significantly in the shade and the growth rate was similar in all the treatments. Significant differences in the leaf emission rate were measured only during the juvenile phase (three weeks after planting) in lettuces and cucumbers and could result from changes in soil temperature. As a conclusion, this study suggests that little adaptations in cropping practices should be required to switch from an open cropping to an agrivoltaic cropping system and attention should mostly be focused on mitigating light reduction and on selection of plants with a maximal radiation use efficiency in these conditions of fluctuating shade. (C) 2013 Elsevier B.V. All rights reserved.

The geo-statistical Kriging method is conventionally used in the spatial dimension to predict missing values in a series by utilizing information from neighbouring data, supported by the hypothesis that mathematical expectation is a function of distance between observations. By using a data-driven machine learning-based inferencing and exploration framework, this research applies a Kriging-based interpolation in the temporal dimension to fill in data gaps in time-series of air temperatures. It assesses its performance for artificial gap scenarios (ranging in length from single one to six consecutive data points) generated using data with both daily and hourly resolutions from five sites in Europe (Laqueuille, France; Grillenburg, Germany; Monte Bondone, Italy; Oensingen, Switzerland; Rothamsted, United Kingdom) and one in France overseas (Sedael, Réunion Island). Results show that the method is capable of predicting missing temperatures with acceptable accuracy, especially with the hourly resolution and for non-high elevation sites: modeling efficiency (EF ≤ 1, optimum)>0.8, with the exception of Monte Bondone, placed at>2000 m a.s.l. (EF < 0). With daily data, maximum temperature was correctly predicted at all sites (0.6 ≤ EF < 0.9), while some less accuracy (down to EF < 0.4) was noted when predicting missing daily minimum temperatures. In conclusion, the method appears suitable to be applied to fill in hourly temperature gaps, requiring more stringent hypotheses concerning daily data and mountain sites (but further studies are required to draw concluding recommendations).

The total uptake of carbon dioxide by ecosystems via photosynthesis (gross primary productivity, GPP) is the largest flux in the global carbon cycle. A key ecosystem functional property determining GPP is the photosynthetic capacity at light saturation (GPPsat), and its interannual variability (IAV) is propagated to the net land–atmosphere exchange of CO2. Given the importance of understanding the IAV in CO2 fluxes for improving the predictability of the global carbon cycle, we have tested a range of alternative hypotheses to identify potential drivers of the magnitude of IAV in GPPsat in forest ecosystems. Our results show that while the IAV in GPPsat within sites is closely related to air temperature and soil water availability fluctuations, the magnitude of IAV in GPPsat is related to stand age and biodiversity (R2 = 0.55, P < 0.0001). We find that the IAV of GPPsat is greatly reduced in older and more diverse forests, and is higher in younger forests with few dominant species. Older and more diverse forests seem to dampen the effect of climate variability on the carbon cycle irrespective of forest type. Preserving old forests and their diversity would therefore be beneficial in reducing the effect of climate variability on Earth's forest ecosystems. Interannual variability (IAV) of the net carbon dioxide exchange over land is globally the main determinant of the variability of atmospheric CO2 growth rate1,2. So understanding the factors controlling the IAV in CO2 fluxes is essential to improve the predictability of the global carbon cycle3. Ecosystem biotic properties — such as soil and canopy nutrient status, rates of change in physiological properties of the vegetation, or the sensitivity of these properties to environmental factors — influence ecosystem CO2 exchange. Recent studies have shown that the IAV of the carbon budget can be better explained by variation in biotic properties of ecosystems such as photosynthetic capacity (GPPsat) than directly by environmental and climatic drivers4,​5,​6. GPPsat is defined as the value of gross primary productivity (GPP) at saturating light under non-stressed conditions, minimizing the influence of anomalous hydrometeorological conditions (for example, droughts and heatwaves), which potentially affect photosynthesis. A robustly retrieved characterization of GPPsat can be regarded as an ecosystem functional property reflecting the physiological response of the ecosystem to the environment. Given that IAV of GPPsat must propagate to observed GPP, this quantity is thought to be a key variable in understanding IAV of carbon fluxes7. In fact, recent studies demonstrated that GPPsat correlates more strongly than any climatic variable with annual GPP8, but also correlates with net ecosystem CO2 exchange5. The magnitude of IAV in GPPsat has been shown to exhibit considerable variation across ecosystems9, yet no obvious explanation for this pattern has been reported in the literature. However, the consequences are important: a low IAV in GPPsat would suggest that ecosystem functioning is not very sensitive to climatic variability, and that it preserves its functionality under the influence of that variability — and, likewise, high IAV is a consequence of high sensitivity. The capability of an ecosystem to preserve its functioning and structure over time (after external disturbances or climate extremes), is often defined as ecosystem stability and is linked to ecosystem resilience10. Using this terminology, low values of IAV in GPPsat can be understood as a characterization of high ecosystem functional stability. The relation of ecosystem functionality, structure and stability has been a matter of debate for many decades in the field of ecology. In particular, the diversity of vascular plants has been investigated as a stabilizing factor with respect to variations in productivity, for example by buffering the ecosystem’s sensitivity to climate extremes11. However, it is also well known that plant diversity is co-limited by soil properties12, ecosystem management, and climate conditions. Another variable to consider is stand age (the mean age of the forest stand or the number of years after a major stand replacement after disturbance), which may affect ecosystem stability through adaptation, particularly of trees to their environment — hence increasing ecosystem resilience to climate variability13. Moreover, structural parameters such as canopy cover, rooting depth, canopy height or leaf area index (LAI), which also depend on tree species diversity and stand age14, have an important effect on the ecosystem response to variation in environmental drivers since they define the capacity of trees to access resources such as water and light15. For instance, a regional study in the Amazon basin has shown that GPP, derived from the remotely sensed enhanced vegetation index, is less sensitive to environmental influences in regions with high canopy cover16. Despite this growing body of ecological knowledge, it remains largely uncertain which factors stabilize ecosystem functional properties at the global scale. In particular, we do not understand the causes of variability of specific ecosystem functional properties, such as photosynthetic capacity across ecosystem types, which ultimately controls ecosystem productivity. Here we hypothesize that stand age and species diversity play an important role in stabilizing ecosystem photosynthetic capacity. We test this hypothesis while also considering other factors related to climate, water availability, forest structure and soil properties that might have direct or indirect effects on ecosystem photosynthetic capacity. In this study, we used measurements of ecosystem-level fluxes, and climate variables (temperature, precipitation, and water availability), species richness, stand age, forest structure (canopy cover, height, and LAI), and soil properties (nutrient availability17) derived from satellite data, in situ observations and the literature (see the Methods). We used half-hourly ecosystem-level GPP fluxes estimated by the means of the eddy-covariance technique at 50 FLUXNET sites18 with at least 4 years of measured fluxes, and with different vegetation types across different climatic regions. We included data from evergreen forest (EF) as well as deciduous broadleaved and mixed forest (DBMF) located in temperate, boreal, mediterranean, tropical and dry climate regions (Supplementary Fig. 1 and Table 1). All 50 sites have information on stand age (referred to simply as ‘age’ in Figs 1–3) and species richness in addition to the CO2 flux data. Species richness (‘sp. no.’ in Figs 1–3) is the number of dominant plant species (for example tree or herb) that account for a cumulative abundance of 90 percent at a given site. We collected additional information on (i) canopy cover, (ii) canopy height, (iii) LAI, (iv) temperature and precipitation, and (v) soil water availability index (WAI) for a subset of 44 sites; and (vi) an index of nutrient availability for 36 sites compiled from the literature17 (see Methods).

application/pdf, 紀要論文, La canicule a caractérisé l'été 2003. La température de l'air, durant l'été 2003, à Zermatt a été largement plus élevée que la valeur moyenne des derniers 20 ans. Concernant le régime du Rhône à la Porte du Scex, le débit estival, notamment celui des mois de juin et d'août a été remarquablement augmenté. L'apport total de ler juin au 31 aout 2003 atteint à 2.77km3, ce qui représente environ la moitié de l'apport annuel, soit 5.6km3 (débit moyen de 1935 à 1980). La sensibilité de la réponse à le débit à la Porte du Scex par la variation de la température de l'air à Zermatt a été analysée: l'effet de la variation de température de l'air à Zermatt apparaît 2 jours après sur le débit à la Porte du Scex. D'autre part l'apport de matières en suspension de juin en août 2003, a été estimée à 2.3×10^ tonnes.

A study was carried out of the changes in moisture and acetic acid contents during the fermentation and convection drying of cocoa beans. A laboratory drier operating by convection or conduction and a series of three volatile acidity extractors based on the Mothe-Efter method were used. An original cutting system made it possible lo analyse five inner layers of cocoa bean from the centre to the outside edge. Processing of the results enabled the determination of the local and overall changes in the moisture and acetic acid contents and showed the influence of air parameters on drying in thin layers.

Highlight text Thermal infrared imagery contributes to the phenotyping of crop response to water stress. Based on multispectral images, the Vegetation Index–Temperature (VIT) concept constitutes a relevant approach., As field phenotyping of plant response to water constraints constitutes a bottleneck for breeding programmes, airborne thermal imagery can contribute to assessing the water status of a wide range of individuals simultaneously. However, the presence of mixed soil–plant pixels in heterogeneous plant cover complicates the interpretation of canopy temperature. Moran’s Water Deficit Index (WDI = 1–ETact/ETmax), which was designed to overcome this difficulty, was compared with surface minus air temperature (T s–T a) as a water stress indicator. As parameterization of the theoretical equations for WDI computation is difficult, particularly when applied to genotypes with large architectural variability, a simplified procedure based on quantile regression was proposed to delineate the Vegetation Index–Temperature (VIT) scatterplot. The sensitivity of WDI to variations in wet and dry references was assessed by applying more or less stringent quantile levels. The different stress indicators tested on a series of airborne multispectral images (RGB, near-infrared, and thermal infrared) of a population of 122 apple hybrids, under two irrigation regimes, significantly discriminated the tree water statuses. For each acquisition date, the statistical method efficiently delineated the VIT scatterplot, while the limits obtained using the theoretical approach overlapped it, leading to inconsistent WDI values. Once water constraint was established, the different stress indicators were linearly correlated to the stem water potential among a tree subset. T s–T a showed a strong sensitivity to evaporative demand, which limited its relevancy for temporal comparisons. Finally, the statistical approach of WDI appeared the most suitable for high-throughput phenotyping.

International audience; The sawfly Cibdela janthina (Hymenoptera: Argidae) native to Sumatra was introduced on La Réunion (France, Indian Ocean) in 2007 to control the giant bramble Rubus alceifolius (Rosaceae), one of the most invasive plants on this island. We determined the influence of temperature on the development duration and survival of C. janthina preimaginal stages in controlled conditions in order to parameterize a survival model and to relate the predicted survival with observed patterns of defoliation of the host plant at different altitudes. We adjusted the Régnière model to survival data, combined with the Lactin-2 model on development rate of the three preimaginal stages of C. janthina. This model adequately predicts the observed defoliation and the altitudinal limit of the biological control agent. Our results also show that studies on temperature-related constraints on the biology of an agent introduced for weed control should be emphasized both in the pre-release and the post-release phases of a biological control program to evaluate the potential success of the control programme. (Résumé d'auteur)

International audience; Predicting accurately the microclimate distributed inside greenhouse equipped with photovoltaic panels is a prerequisite for sustainable energy-saving greenhouse management. It can also help to improve designers in improving the design of these kinds of greenhouse while enhancing the radiation transmission inside. This study is an essential prerequisite for research on crop namely those adapted to specific conditions in greenhouses equipped with photovoltaic panels. With this mind, the solar radiation distribution, thermal air, water vapour and dynamics fields were simulated using the CFD model in two types of greenhouses (Asymmetric and Venlo) equipped with photovoltaic panels on their roof, as well as crop cover characteristics and the interactions between crops and airflow. A detailed description of the thermal, dynamic and radiation fields inside the greenhouse were obtained and the analysis of data collected during this study show that (i) the solar radiation is more evenly distributed in the Venlo greenhouse than in the Asymmetric greenhouse. On an average, the solar radiation transmission in the Asymmetric greenhouse is 41.6% whereas that of the Venlo greenhouse is 46%. These luminosity values are not well adapted to plant requirements. (ii) For the same boundary conditions, the Venlo greenhouse has a cooler climate than the Asymmetrical greenhouse (-3°C in summer and -3°C in winter). This effect is beneficial in summer, but not interesting in winter. The various different openings in the Venlo greenhouse help to maintain temperature control and a homogeneous climate (temperature variation of 5°C in summer and 3.3°C in winter)

International audience; La stratosphère se refroidit sous l'effet de la diminution d'ozone et de l'augmentation de l'effet de serre. Même si les observations disponibles, qui n'ont pas été prévues initialement pour des études climatiques, présentent toutes de fortes discontinuités temporelles, on identifie clairement ce refroidissement, avec des variations en fonction de l'altitude et de la latitude. Cependant, les incertitudes concernant la quantification de ces tendances varient d'un facteur 2. Dans le futur, la synergie entre les mesures spatiales et celles depuis le sol devra se renforcer afin d'assurer notamment une meilleure continuité entre les instruments SSU et AMSU.

International audience; Les radars météorologiques ont été initialement conçus pour détecter et quantifier les précipitations. Une nouvelle technique a été proposée à la fin des années 1990 pour mesurer le changement de l'indice de réfraction de l'air dans les basses couches de l'atmosphère en exploitant la phase du signal provenant de cibles fixes situées autour du radar. Cette mesure donne des informations sur l'indice de réfraction de l'air, lui-même combinaison de la pression, de la température et de l'humidité, et présente donc un intérêt météorologique, aussi bien pour la prévision numérique que pour les études de processus.

Ascochyta blight (Mycosphaerella pinodes) development on pea is affected by leaf wetness duration (LWD) and temperature (1). The aim of this study was to investigate the effects of canopy architecture and development on microclimate and on ascochyta blight development in pea canopies with contrasting architectures under field conditions.A split-plot experiment was conducted at Le Rheu, France, in the spring of 2009 and 2010 with three pea cultivars (Athos, Antares and Gregor), each sown at two densities (80 and 40 seeds/m²) plus a third density in 2010 (30 seeds/m²). LWD and air temperature (Ta) were estimated respectively with leaf wetness sensors and thermocouples at the bottom and middle height of each canopy. Two mesoclimate parameters (LWD and Ta) were recorded with sensors placed at 1.50 m above the soil level. For each cropping season, microclimatic conditions prevailing during wetness episodes were compared according to the presence or absence of rainfall (rainfall and dry periods respectively).Differences were observed between meso- and microclimate parameters only on LWD but not on Ta. During rainfall periods, LWD was longer inside the canopy than outside (more than 3 to 10h daily). Conversely, during dry periods, LWD became shorter inside the canopy after canopy closure (decreased of 1 to 7h daily). In the denser canopies, these differences appeared first at the bottom. During dry periods, LWD due to dew was longer in the middle than at the base of the canopy, with an average daily LWD of around 4h that decreased during canopy development. When the canopy was completely closed, no LWD was recorded at the base of the plants. Moreover, cultivar Gregor with the greatest leaf area index (LAI) provided lower LWD than the two other cultivars. A plant density effect was also observed in 2010 with longer LWD (more than 2 to 6h daily) in the canopies with the lowest density for each cultivar as soon as canopy was closed. During rainfall periods, no leaf wetness distribution patterns were observed inside the canopy whatever the cultivar or the plant density with an average daily LWD of around 15h. In 2009, longer LWD were observed at the base level for each cultivar sown at the greatest density from two weeks before canopy closure (more than 2 to 5h daily). Regarding the effect of microclimate on disease development, we observed that during dry periods, temperatures were too low during wetness periods to favour disease development and correspondingly, a prediction model adapted from Magarey et al. (2) showed that infection periods occurred only during rainfall periods.Denser canopies limit water evaporation and prevent dew formation on leaves while the lowest canopy densities favour dew formation. Therefore the microclimates of denser canopies are the more favourable to disease development and led to greatest disease severities.

Many cultivars of water yam (Dioscorea alata) are affected by anthracnose epidemics due to Colletotrichum gloeosporioides. While there is neither authorized nor advisable pesticide treatment, the only way to limit disease impact is to use combination of partial plant resistances and cultural practices limiting fungi dispersion and development. Staking was traditionally used to grow yam on small plots but was no longer used in larger mechanized yam plots.In order to evaluate the role of staking in anthracnose epidemiology, we designed in 2011 an experiment to compare the disease dynamics and the microclimate within staked and unstaked yam plots. We recorded microclimatic variables (Radiation budget, wind speed, air temperature and relative humidity) 2 m above ground outside the plots and 1 m above ground into the plots between rows of 2m high stakes. Leaf temperature (LT) and leaf wetness duration (LWD) were recorded by appropriate sensors placed in vegetation at the bottom and the top of the stakes near the ground in unstaked plants.LWD was always recorded by all sensors when rainfall was greater than 1mm in a 15 minute time step. For a given rainfall, LWDs were longer in unstaked that in staked crop (up to 8 h LWD in unstaked plot, for 2 h LWD in staked plot). During clear nights with no rain, dew was deposited and measured LWDs were longer at the bottom than at the top of the stakes. Consistent differences of LT in the three canopy conditions were observed and confirmed by latent heat fluxes calculated from microclimatic data. The data recorded along the experiment were used to calibrate LWD models for the three canopy conditions. Simulations of LWD with data from two weather stations in contrasted climatic conditions of Guadeloupe, showed that staking may be efficient to limit periods favourable for disease development in drier climate, but not in regions where rainfalls are more frequent and intense.While traditional staking provides dense vegetation mound, trellising is increasingly used for yam. This practice leading to new vegetation spatial distribution may exhibit antagonist effect on fungi development and dispersion and should be investigated.

International audience; The subject of change detection in climate time series has recently received greater interest as the perception of a human-induced change in the climate is now widely accepted. However, changes in regional precipitation and temperature remain uncertain. This study characterizes projected fine-scale changes in precipitation and temperature in continental Southeast Asia over the period 1960-2049. Twenty four annual variables were derived from grid-based daily precipitation and temperature produced by the PRECIS regional climate model under A2 and B2 scenarios. These time series, capturing precipitation intensities (classified as low, medium and high), seasonality and extremes in precipitation and temperature, were subjected to the modified Mann-Kendall trend detection test accounting for long-term persistence. The results indicate that temperature increases over the whole region with steeper trends in higher latitudes. Increases in annual precipitation, mainly restricted to Myanmar and the Gulf of Thailand, result from increases in high precipitation during the wet season. Decreases are observed mainly over the sea and caused by a reduction of low precipitation. Changes in the occurrence of the monsoon affect the low-latitude sea areas only. By showing that significant precipitation change are minor over land areas, these results challenge most of the previous studies that suggested significant precipitation changes over Southeast Asia, often mixing up multi-decadal variability and long-term unidirectional trends. Significant changes in precipitation and temperature may induce higher agricultural yields as steepest temperature and precipitation increases will predominantly affect the coldest and driest land areas of the region.

International audience; Precision irrigation requires frequent information on crop conditions spatial and temporal variability. Image-based remote sensing is one promising techniques for precision irrigation management. In this study, we investigated the use of broad band multispectral (visible, near infrared and thermal infrared bands) and thermal airborne imagery for the characterization of water status of durum wheat crop through two indices: the Water Deficit Index (WDI) and the Simplified Surface Energy Balance Index (S-SEBI). Compari - sons between these two indices and the ratio between actual and potential evapotranspiration (AET/PET) show that such techniques are promising for precision irrigation management.

International audience; In this study, we developed a remote sensing approach, normally applied to management of crop irrigation, with the purpose of phenotyping a plant population in the field. The experiment was performed on 'Starkrimson' x 'Granny Smith' apple progeny (122 hybrids, 4 replicates) at adult stage, cultivated in field on Diaphen platform (INRA Montpellier, France). Airborne images acquisition in RGB and NIR bands permit to compute the Normalized Difference Vegetation Index (NDVI), while differences between tree canopy surface measured by thermal IR imaging (Ts) and air temperature (Ta) made it possible to calculate water stress indices. The Water Deficit Index (WDI), derived from the Crop Water Stress Index (CWSI), was considered for its applicability to discontinuous plant cover. WDI was computed on each individual tree, and focused on its central zone (60 cm diameter buffer). The first results showed significant genotypic effects and drought effects for indices during imposed summer water shortage, without interaction between them. Moreover, this first experiment permits to determine field measurements that are necessary to validate the method, linking image interpretation and tree water status variables.; Dans le cadre de cette étude, nous avons développé une approche de télédétection, normalement appliquée à la gestion de l’irrigation des cultures, afin de phénotyper une population végétale aux champs. L’expérience a été effectuée sur une descendance de pommiers ‘Starkrimson’ x ‘Granny Smith’ (122 hybrides, 4 répétitions) au stade adulte, cultivés aux champs sur plate-forme Diaphen (INRA Montpellier, France). L’acquisition d’images aériennes dans les bandes RGB et NIR a permis de calculer l’Indice de Végétation Normalisé (NDVI), tandis que les différences entre la surface de la canopée des arbres mesurée par images thermiques IR (Ts) et la température de l’air (Ta) ont permis de calculer les indices de stress hydrique. L’Indice de Déficit Hydrique (WDI), dérivé de l’Indice de Stress Hydrique des Cultures (CWSI), a été considéré en raison de son applicabilité à un couvert végétal discontinu. Le WDI a été calculé pour chaque arbre individuel, en se focalisant sur sa zone centrale (avec une zone-tampon de 60 cm de diamètre). Les premiers résultats montrent des effets génotypiques significatifs et des effets de la sécheresse pour les indices pendant la pénurie d’eau imposée en été, sans interaction entre eux. De plus, cette première expérience permet de déterminer les mesures de terrain qui sont nécessaires pour valider la méthode, mettant en rapport l’interprétation des images et les variables liées à l’état hydrique des arbres.

Les prévisions de dates de récolte d'ananas sont essentielles à la planification du travail et aux efforts de commercialisation des fruits frais. L'objectif de cette étude a été de développer un modèle basé sur la température de l'air minimale et maximale du jour afin de prévoir les dates de récolte d'ananas quel que soit l'environnement dans lequel la plante est cultivée. Pour la modélisation, deux phases de développement du fruit ont été distinguées : période entre induction du développement du fruit et ouverture de la première fleur et période entre ouverture de la première fleur et récolte. Pour la première phase, les prévisions sont basées sur l'accumulation des unités de chaleur à partir de la température de l'air essentiellement. Quant à la seconde phase, les unités de chaleur sont accumulées à partir de la température estimée du fruit. Le modèle a été calibré et testé à partir de nombreuses données en provenance de plusieurs pays producteurs et sous différents environnements et latitudes : Queensland, Australie, Côte d'Ivoire, Hawaï, Thaïlande. Le modèle a prédit les dates de récolte avec une erreur moyenne de 11,3, 12 et 5d respectivement pour chacun des pays. Cette marge d'erreur reste acceptable pour la plupart des planteurs d'ananas

On dénombre divers modèles de simulation de la mouche du chou (Delia radicum L.), mais plusieurs comportent d’importantes lacunes au niveau des différences génotypiques de l’insecte et des paramètres utilisés. L’objectif principal de ce projet est de rassembler les informations manquantes afin de créer dans le futur un modèle bioclimatique permettant de simuler efficacement la dynamique des populations de ce ravageur. L’effet de la température et de l’humidité du sol a été mesuré sur les œufs et les larves de la mouche du chou. L’humidité n’influence la survie des œufs qu’en dessous de 25% [m/m]. L’exposition graduelle des œufs à des températures élevées au dessus de 33°C affecte également la survie. La survie des larves augmente avec la hausse des températures et de l’humidité. Nous croyons que la mouche du chou est bien adaptée aux conditions des sols organiques au Québec, et nous recommandons l’intégration de la température du sol pour les stades au sol plutôt que de l’air dans l’élaboration d’un nouveau modèle. La ponte a également été étudiée à partir de différents critères préétablis pour chacun des génotypes hâtifs et tardifs, à différentes températures. Excepté pour la pré-oviposition qui est plus longue chez les hâtifs, aucune différence n’a été observée entre les génotypes. La majorité des critères, excepté la durée d’un épisode de ponte et la mortalité des œufs, a réagit à la température. Les nouvelles informations serviront à l’élaboration ou le perfectionnement d’un modèle de simulation de la dynamique de la ponte de la mouche du chou., Few simulation models for the cabbage maggot (Delia radicum L.) had been seen, but several include significant weaknesses for the insect genotypic differences and parameters used. The main objective of this project is to collect the missing information to create, in the future, a bioclimatic model that will efficiently simulate the dynamics of the populations of this pest. The effect of soil temperature and moisture had been measured on eggs and larvae of the cabbage maggot. Humidity affects egg survival below 25% [w/w]. Gradual exposure of eggs to high temperature above 33°C also affects survival. Under tested conditions, larvae survival increases with rising temperatures and humidities. We believe that the maggot is well adapted to muck soil in Quebec, and we recommend to incorporated soil temperature rather than air temperature for above-ground stages into the development of a new model. Egg-laying activity has also been studied from various pre-established criterions for each of the early- and late-emerging genotypes, at different temperatures. Except for the pre-oviposition which is longer for the early genotype, no differences were observed between genotypes. The majority of criterions, except for the duration of oviposition bouts and egg mortality, responded to temperature. The new information will be used for the preparation and development of a simulation model of the egg-laying dynamic of the cabbage maggot., Réalisé en cotutellle avec Gaétan Bourgeois et avec la participation de Guy Boivin, d'Agriculture et Agroalimentaire Canada, du Centre de Recherche et Développement en Horticulture à Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada