Search results for "Quercus"
showing 10 items of 125 documents
Spatio-temporal variation of throughfall in a hyrcanian plain forest stand in Northern Iran
2018
Abstract Elucidating segregation of precipitation in different components in forest stands is important for proper forest ecosystems management. However, there is a lack of information on important rainfall components viz. throughfall, interception and stemflow in forest watersheds particularly in developing countries. We therefore investigated the spatiotemporal variation of important component of throughfall for a forest stand in a Hyrcanian plain forest in Noor City, northern Iran. The study area contained five species of Quercus castaneifolia, Carpinus betulus, Populus caspica and Parrotia persica. The research was conducted from July 2013 to July 2014 using a systematic sampling method…
Diffusion of Oxygen through Cork Stopper: Is It a Knudsen or a Fickian Mechanism?
2014
International audience; The aim of this work is to identify which law governs oxygen transfer through cork: Knudsen or Fickian mechanism. This is important to better understand wine oxidation during post-bottling aging. Oxygen transfer through cork wafers is measured at 298 K using a manometric permeation technique. Depending on the mechanism, we can extract the transport coefficients. Increasing the initial pressure of oxygen from 50 to 800 hPa leads to a change in the values of the transport coefficients. This implies that oxygen transport through cork does not obey the Knudsen law. From these results, we conclude that the limiting step of oxygen transport through cork occurs in the cell …
Sorption behavior of volatile phenols at the oak wood/wine interface in a model system.
2006
The sorption in a model system of aroma compounds of enological interest (mixture of the eight derivatives from guaiacol, 4-ethylphenol, and whiskylactone) onto wood was investigated to assess the influence of wood on the concentration of these volatiles during the aging of wine. To evaluate the influence of the solubility of aroma compounds in sorption phenomena, this parameter was determined for each volatile compound in model wine at 10 and 25 degrees C. The solubility is significantly higher in the model wine than in water and remains constant in the range of temperatures studied, except for guaiacol and vanillin. Kinetic and equilibrium sorptions were investigated. Sorption kinetics sh…
Dendroarchaeological contributions to the history of forest exploitation: the case of the Gallo-roman settlement of Oedenburg (Alsace, France) betwee…
2011
International audience; Dendro-archaeological contribution to the history of forest exploitation. The case of the Gallo-Roman settlement of Oedenburg (Alsace, France) between 10 and 180 AD summary Dendrochronology has never been considered as simply a dating tool. In addition to the dates, which are always based on a regional scale signal, tree-ring series can provide information about forest structure and woodland development. Our study of the settlement of Oedenburg, established in the Rhine Limes of the Roman Empire, was conducted within this framework. The dated series provide a description of some structural aspects of oak-stands that were exploited for construction. In this aim, the a…
Different Sorption Behaviors for Wine Polyphenols in Contact with Oak Wood
2007
The evolution of polyphenols of enological interest- monomeric anthocyanins, (+)-catechin, (-)-epicatechin, gallic acid, and trans-resveratrol-in the presence of oak wood was investigated in aging-model conditions. Disappearance kinetics showed that, except for gallic acid, all of the wine polyphenols tend to disappear from the model wine in presence of oak wood, to reach an equilibrium after 20 days of contact. At equilibrium, the higher disappearance rates were obtained for monomeric anthocyanins and trans-resveratrol with values of 20 and 50%, respectively. For monomeric anthocyanins, the rate of disappearance seemed to be independent of their nature. In order to evaluate the contributio…
Microscopical and Mycological Investigations on Wood of Pendunculate Oak (Quercus robur L) Relative to the Occurrence of Oak Decline
1996
Summary Microscopical studies exhibited great differences between healthy and damaged pendunculate oak trees (Quercus robur L.) relative to the state of sapwood vessels and the degree of fungal infection. In the sapwood of damaged trees deposits, discolorations and early tylosis formations were found which frequently occurred in combination with fungal infections. These results lead to the assumption that the defence reaction of the trees probably induced by fungal infection changes the structure of the tree vessels to such an extent that their water transfer function is disturbed. Some fungal genera playing an important role in the discussion of the causes of oak decline could be isolated.…
Sorption Equilibria of Ethanol on Cork
2013
International audience; We report here for the first time a thermodynamic study of gaseous ethanol sorption on raw cork powder and plate. Our study aims at a better understanding of the reactivity of this material when used as a stopper under enological conditions, thus in close contact with a hydroethanolic solution, wine. Sorption−desorption isotherms were accurately measured by thermogravimetry at 298 K in a large range of relative pressures. Sorption enthalpies were determined by calorimetry as a function of loading. Sorption−desorption isotherms exhibit a hysteresis loop probably due to the swelling of the material and the absorption of ethanol. Surprisingly, the sorption enthalpy of e…
The role of plant species on runoff and soil erosion in a Mediterranean shrubland.
2021
Shrubland is a Mediterranean biome characterized by densely growing evergreen shrubs adapted to fire events. To date, scientific research has focused on the impact of vegetation on soil erosion mainly through the control that plant biomass or plant cover exerts on sediment delivery and runoff discharge, being the individual plant species influence on hydrological and erosional processes not achieved in detail. The objective of this research is to determine: i) runoff and soil losses in a shrubland-covered rangeland at Sierra de Enguera, Spain; and ii) how four plant species affect soil and water losses. We measured soil cover, soil properties, runoff discharge and sediment yield under natur…
The combined effects of CO2, ozone and drought on rubisco and nitrogen metabolism of young oak trees (Quercus petraea) A phytotron study
1998
Abstract In this phytotron experiment we investigated the influence of increased CO 2 , O 3 and drought on the content of soluble proteins and some enzymes of carbon and nitrogen metabolism. We found that the amounts of soluble proteins and the large subunit of the rubisco per fresh weight in young oak leaves declined under conditions of increasing levels of CO 2 and after temporary water stress. The activities of nitrite reductase and glutamine synthetase were reduced when O 3 and CO 2 levels were raised.
Contribution to the knowledge of the Cynipidae (Hymenoptera) of Jordan
2006
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