eKhSACIR інституційному репозитарії Харківської державної академії культури
Not a member yet
7410 research outputs found
Sort by
Spatial ecological processes allow tree-grass coexistence in savannas despite repeated fires
No full textInternational audienceRepeated fires could prevent tree encroachment in the grass stratum of savannas. However, there are some ecological mechanisms that allow invasion of trees in moist grasslands and eventually, when trees reach high density, prevent fire spread. To better understand the interplay between fire and tree encroachment, we developed a spatially explicit individual-based model representing the interactions between grass, fire spread and trees We considered three different sets of tree life history traits characterizing three types of trees, namely resprouters, resisters, and avoiders Resprouters are able to resprout after their aboveground biomass is burned, resisters can resist fire due to a thick bark developed in early age, avoiders are very fire vulnerable but tend to grow fast. The results of the model show that these three strategies allow tree invasion in the grass stratum despite repeated fire. Resprouters form a population of gullivers (alive trees whose aboveground biomass is burned) persisting repeated fires, resisters could grow slowly from year to year despite fires, and avoiders form clusters where fire cannot spread The three simulated tree strategies demonstrated that, in savannas, spatial interactions between trees, grass and fire spread are able to allow tree invasion into the grassland stratum despite repeated fires, and allow tree-grass co-existence in savannas for a transient period, before the complete canopy closure We remark that the inclusion of space in the model is fundamental in achieving our results, and spatial interactions in savannas are among the mechanisms allowing tree-grass coexistence
Dia-nanofiltration as a convenient detoxification process for producing fermentable substrates from lignocellulosic biomass hydrolysates
No full textDia-nanofiltration as a convenient detoxification process for producing fermentable substrates from lignocellulosic biomass hydrolysates. 16. Congrès de la Société Française de Génie des Procédés "Le Génie des Procédés au Service de l'Homme" (SFGP 2017
Characterization of several aldehyde dehydrogenases in moss Physcomitrella patens
No full textInternational audienc
What drives the inter-annual variations in C flux and balance in a tropical rainforest of French Guiana?
No full textInternational audienc
Implantation-related genes in the ovine endometrium are regulated by extracellular vesicles from earlypregnant uterine fluids
No full textSession 4: Reproduction, Milks, Plants L. Galio: présentation orale sélectionnéeNational audienc
Efficiency of different BLUP indexes accounting for polyandry in bee genetic evaluation
No full textInternational audienc
Dynamique à long terme du phosphore dans deux essais au champ du réseau SOERE-PRO
No full textNational audienc
Un critère d'évaluation pour les K-moyennes prédictives
No full textL’algorithme des K-moyennes prédictives est un des algorithmes de clustering prédictif visant à décrire et à prédire d’une manière simultanée. Contrairement à la classification supervisée et au clustering traditionnel, la performance de ce type d’algorithme est étroitement liée à sa capacité à réaliser un bon compromis entre la description et la prédiction. Or, à notre connaissance, il n’existe pas dans la littérature un critère analytique permettant de mesurer ce compromis. Cet article a pour objectif de proposer une version modifiée de l’indice Davies-Bouldin, nommée SDB, permettant ainsi d’évaluer la qualité des ré- sultats issus de l’algorithme des K-moyennes prédictives. Cette modification se base sur l’intégration d’une nouvelle mesure de dissimilarité permettant d’établir une relation entre la proximité des observations en termes de distance et leur classe d’appartenance. Les résultats expérimentaux montrent que la version modifiée de l’indice DB parvient à mesurer la qualité des résultats issus de l’algorithme des K-moyennes prédictives
Adjustements of Mechanical and Hydraulic Properties of Wood Formed under Environmental Stresses
No full textInternational audienceTrees adjust their development to the environmental conditions they experience. Storms events of last decades showed that acclimation of trees to mechanical stresses due to wind is a very important process that allow the trees to sustain for long years. In the future, trees will experience new wind patterns, namely, more often strong winds and fewer daily moderate winds. Moreover, these patterns will go along with drought periods that may interact with the capacity of trees to adjust their growth to mechanical stresses due to wind. It is necessary to understand the mechanisms of wood functional acclimations to environmental conditions in order to predict their behaviour and in order to give foresters and breeders the relevant tools to adapt their forest management. This work aims to study how trees adjust the mechanical and hydraulic functions of their wood to environmental stresses and how this acclimation may be beneficial for the tree to resist to future stresses. In this work, young poplars were grown under controlled climatic conditions that include permanent environmental stress (daily mechanical stress of the stem by bending and/or hydric stress). Then, the properties of wood formed under these stressed conditions were characterized. First, hydraulic conductivity and sensibility to cavitation were measured at the tissue level in order to evaluate the changes in water transport capacity. Secondly, bending tests and Charpy impact tests were carried out at the millimetric scale to locally measure mechanical parameters such as elastic modulus, elastic limit or rupture energy. These experimental data allow to evaluate the impacts of mechanical and water stress on the wood material. At the stem level, they will be merged in an integrative model in order to evaluate the beneficial aspect of wood acclimation for trees
