Caractérisation de la qualité du liège selon l'état sanitaire des arbres par la méthode d'analyse d'image - Cas des forêts de M'Sila et de Zarieffet (Nord-Ouest Algérien) -

Cet article nous présente une étude détaillée de la qualité du liège selon l'état sanitaire d'arbres de deux zones de production en Algérie, l'une littorale et l'autre de montagne. On y voit que les composantes environnementale, géographique et génétique de l'arbre interfèrent avec le facteur sanitaire, modifiant la physiologie et la croissance du liège, des pores et par voie de conséquence les autres anomalies physiologiques

La filière liège algérienne, entre passé et présent

D’un passé très florissant, la filière liège en Algérie va aujourd’hui vers un avenir incertain. Les potentialités productives de cette suberaie rivalisaient à l’époque avec celles du Portugal et de l’Espagne. D’un record jamais égalé de 553 000 q en 1937, la production algérienne n’a pas dépassé 65000 q en 2010. Une exploitation intensive appliquée aux peuplements durant l’époque coloniale (1847-1960) a favorisé l’industrie et le commerce du liège. Les exportations sont passées de 50 000 q en 1867 à 475 000 q en 1930, tandis que l’industrie locale comptait durant les années 1950 pas moins de 100 entreprises situées à proximité des forêts et employait 5 000 ouvriers. Trois ans après l’indépendance de l’Algérie, la filière liège a repris du service sur les mêmes cadences qu’à l’époque coloniale, avec une production maximale de 350 000 q. Malheureusement, durant les 45 ans d’exploitation continue qui ont suivi (1965-2010), la superficie productive a régressé significativement pour atteindre 220 000 ha et la production va en décroissant d’année en année. Les grandes orientations des politiques économiques de l’Etat et la centralisation de l’administration forestière ont joué défavorablement envers des peuplements vieillissants et affaiblis par le passé et par les incendies récurrents

Cork oak and climate change: disentangling drought effects on cork chemical composition

Climate change induces in the Mediterranean region more frequent and extreme events, namely, heat waves and droughts, disturbing forest species and affecting their productivity and product quality. The cork oak (Quercus suber) is present along the western Mediterranean basin and its outer bark (cork) is sustainably collected and used for several products, mainly wine bottle stoppers. Since most cork properties arise from its chemical composition, this research studies the effect of drought on cork chemical composition (suberin, lignin, polysaccharides and extractives) and on polysaccharide and suberin monomeric composition. Three sets of cork samples, from the same site, were examined: in one set the cork grew without drought; in another two drought events occurred during cork growth and in the third one drought event happened. The results show that, in general, drought does not affect the proportion of the main components of cork, the monomers of suberin or of polysaccharides, with few exceptions e.g. drought increased ethanol extractives and xylose in polysaccharides and decreased arabinose in polysaccharides. The variability associated to the tree is much more relevant than the effect of drought conditions and affects all the parameters analyzed. Therefore, our research suggests that the tree genetic information, or its expression, plays a much more important role on the chemical composition of cork than the drought conditions occurring during cork growth. In practical terms, the potential increased occurrence of droughts arising from climatic changes will not compromise the performance of cork as a sealant for wine bottlesinfo:eu-repo/semantics/publishedVersio

Flammability of some companion species in cork oak (Quercus suber L.) forests

Key message The high flammability of some companion species in Quercus suber forests, estimated in laboratory tests, could potentially generate an increase in fire vulner_x0002_ability and in fire risk. & Context Recurrent wildfire is one of the main causes of forest degradation, especially in the Mediterranean region. Increased fire frequency and severity due to global change could reduce the natural resilience of cork oak to wildfire in the future. Hence, it is important to evaluate the flammability of companion species in cork oak forests in the particularly dry bioclimatic conditions of North Africa. & Aims This study aimed to assess and compare flammability parameters at laboratory scale among ten companion frequent species in cork oak forests. & Methods Fuel samples were collected in a cork oak (Quercus suber L) forest in the southern part of the mountains of Tlemcen (Western Algeria). A series of flammability tests were carried out using a Mass Loss Calorimeter device (FTT ®). A cluster analysis to classify flammability of the selected species was conducted using the K-means algorithm. & Results The results revealed differences in the four flamma_x0002_bility parameters (ignitability, sustainability, combustibility and consumability), in both fresh and dried fine fuel samples from Quercus suber, Pinus halepensis, Quercus ilex, Quercus faginea, Erica arborea, Arbutus unedo, Pistacia lentiscus, Calicotome spinosa, Juniperus oxycedrus and Tetraclinis articulata. Application of the K-means clustering algorithm showed that C. spinosa, T. articulata, J. oxycedrus and P. halepensis are highly flammable because of their high com_x0002_bustibility and sustainability. & Conclusion The findings identify species that could poten_x0002_tially increase the vulnerability of cork oak forests to forest fires

Caractérisation de la qualité du liège selon l'état sanitaire des arbres par la méthode d'analyse d'image - Cas des forêts de M'Sila et de Zarieffet (Nord-Ouest Algérien) -

International audienceCet article nous présente une étude détaillée de la qualité du liège selon l'état sanitaire d'arbres de deux zones de production en Algérie, l'une littorale et l'autre de montagne. On y voit que les composantes environnementale, géographique et génétique de l'arbre interfèrent avec le facteur sanitaire, modifiant la physiologie et la croissance du liège, des pores et par voie de conséquence les autres anomalies physiologiques

New bench-scale protocols for characterizing bark flammability and fire resistance in trees Application to Algerian cork

This study proposes new bench-scale protocols for evaluating the flammability of bark and its involvement in resistance of trees to fire. Samples of cork from Algerian oak forests (Quercus suber) were selected for flammability testing. A mass loss calorimeter device, arranged in the standard horizontal configuration, was used to determine Heat Release Rate and temperatures. A calibrated epiradiator, arranged in a vertical configuration (to resemble field conditions), was used to determine lethal temperatures in living tissues and to assess the inter-device reproducibility of the data. Both protocols showed good repeatability and reasonable reproducibility. The time to reach lethal temperatures beside living tissues was more than 2 min in all cases and the average time was 230 s. The resistance of cork to fire increased with the thickness of the material, showing that trees in which the cork is less than 3 cm thick are most vulnerable to fire. The importance of corkback tissue in the flammability of cork is also highlighted, indicating important differences in the flammability of industrially processed cork and natural cork. The proposed protocols can be implemented using other devices (i.e. cone calorimeter) to obtain more information about the flammability of different types of tree bark, fire resistance and heat transfer during wildfire. © 2015 The Author(s)