Heat treatment is an effective method to improve biological resistance of low natural durability wood species. The aim of this study was to enhance the decay resistance of Pinus patula, an African low natural durability softwood species, via wood thermal modification technique. Heat treatment was performed on wood specimens under inert conditions at different heat treatment intensities to reach mass losses of 5, 10 and 15%. Heat treated specimens were exposed to fungal decay using the brown rot fungus Poria placenta. The wood chemical and elemental composition was determined as well as extractives toxicity before and after wood thermal modification to understand the reasons of durability improvement. The treated specimens exhibited a significant increase in their durability against wood decay in line with the severity of the treatment. Wood holocellulose was found to be distinctly more sensitive to the heating process than the lignin constituent. In addition, obvious correlations were observed between weight losses recorded after fungal exposure and both holocellulose decrease and lignin ratio increase. The same correlations were observed with the elemental composition changes allowing using the observed differences for predicting of wood durability conferred by heat treatment. Furthermore, no significant differences were M. Pétrissans · P. Gérardin ( ) observed between the toxicity of Pinus patula wood extractives before and after its thermal modification. Einfluss der Stärke der Wärmebehandlung auf die chemische Zusammensetzung und die Dauerhaftigkeit von Kiefernholz (Pinus patula)Zusammenfassung Wärmebehandlung ist eine effektive Methode zur Verbesserung der biologischen Resistenz von Holzarten mit geringer natürlicher Dauerhaftigkeit. Ziel dieser Studie war es, die Fäuleresistenz von Pinus patula, einer afrikanischen Nadelbaumart mit geringer natürlicher Dauerhaftigkeit, durch eine Wärmebehandlung zu verbessern. Dabei wurden Prüfkörper unter Schutzgas mit unterschiedlicher Intensität wärmebehandelt, um Masseverluste von 5, 10 und 15 % zu erreichen. Die wärmebehandelten Prüfkör-per wurden einem Befall mit dem Braunfäulepilz Poria placenta ausgesetzt. Die chemische und Elementzusammensetzung des Holzes sowie die Extraktstofftoxizität wurden vor und nach der thermischen Behandlung bestimmt, um die Gründe der verbesserten Dauerhaftigkeit herauszufinden. Die Dauerhaftigkeit der behandelten Prüfkörper stieg in Abhängigkeit der Behandlungsintensität signifikant an. Die Holzholocellulose reagierte wesentlich stärker auf die Wär-mebehandlung als das Lignin. Dabei wurden deutliche Korrelationen zwischen dem Masseverlust und dem Holzcelluloserückgang sowie dem Anstieg des Ligninanteils festgestellt. Die gleichen Korrelationen ergaben sich für die Änderung der Elementzusammensetzung, wodurch die Verwendung der beobachteten Unterschiede zur Vorhersage der Dauerhaftigkeit von wärmebehandeltem Holz möglich ist. Des Weiteren ergaben sich keine signifikanten Unterschiede zwischen der Toxizität der Holzextraktstoffe von Pinus ...

A large amount of flavonoid has been extracted and isolated from the heartwood of Prosopis juliflora, an exogenous wood species of Kenya. Structural and physicochemical elucidation based on FTIR, (1)H and (13)C NMR, GC-MS and HPLC analysis clearly demonstrated the presence of (-)-mesquitol as the sole compound without any noticeable impurities. The product was able to slow down oxidation of methyl linoleate induced by AIBN. The important amount and high purity of (-)-mesquitol present in the acetonic extract of P. juliflora could therefore be of valuable interest as a potential source of antioxidants from a renewable origin.

Abstract• Identification of extractives present in Cupressus lusitanica heartwood has been conducted using GC-MS analyses. The chromatogram of toluene/ethanol extracts indicated the presence of large amounts of benzaldehyde and numerous terpenic compounds such as cedrol, agathadiol, epimanool, bornyl acetate, α-cedrene and β-cedrene.• The effect of these extractives on the natural durability of cypress wood was investigated on heart wood blocks exposed to pure culture of Poria placenta before or after solvent extraction. Weight losses revealed severe fungal degradations on the extracted blocks compared to unextracted ones.• Efficiency of heartwood extractives as inhibitors of the growth of Poria placenta on malt/agar test confirms their contribution to cypress natural durability.• Cypress blocks were treated at 240 • C for different times to reach different levels of thermodegradation to evaluate effect of heat treatment on fungal durability. Results indicate that evaporation of volatile extractives during the first few minutes of heat treatment contribute to decreased wood durability, while longer treatment times lead to the expected improvement of durability.• This study suggests that the content of extractives, which may be modified during wood drying or weathering processes, could be the origin of the conflicting data described in the literature concerning cypress natural durability. Mots-clés :Cupressus lusitanica / durabilité / extractibles / traitement thermique / pourriture Résumé -Effet des extractibles sur la durabilité naturelle du duramen de cyprès.• Les extractibles présents dans le duramen de Cupressus lusitanica ont été analysés par GC-MS. Le chromatogramme des extraits obtenus à l'aide d'un mélange toluène/éthanol met en évidence des quantités importantes de benzaldéhyde et de nombreux composés terpéniques comme le cédrol, l'agathadiol, l'épimanool, l'acétate de bornyl, l'α-cédrène et le β-cédrène.• L'effet des extractibles sur la durabilité naturelle du cyprès a été évalué à l'aide d'essais réalisés sur des blocs préalablement extraits ou non puis exposés à Poria placenta. Les pertes de masse mettent en évidence une dégradation importante des échantillons extraits comparativement aux témoins non extraits.• L'efficacité des extractibles comme inhibiteur de croissance de Poria placenta a été évaluée. Les résultats indiquent une forte inhibition du développement fongique.• Des blocs de cyprès ont été traités à 240 • C pendant des temps variables pour atteindre différents niveaux de thermo-dégradation. L'évaporation des extractibles volatils durant la première phase du traitement thermique conduit à une diminution de la durabilité du bois aux agents de pourriture, alors que des traitements plus longs conduisent à l'augmentation de durabilité attendue.• Cette étude suggère que la teneur en extractibles, susceptible de varier suite au séchage ou aux intempéries, peut être à l'origine des observations contradictoires rapportées dans la littérature concernant la durabilité naturelle du cyprès.

Watershed and riparian areas of Mau Forest Complex in Kenya are experiencing increased threats due to unsustainable land use activities geared towards economic growth amidst growing population. This study was carried out to examine effects of land use activities on riparian vegetation, soil and water quality along two major rivers (Chemosit and Kipsonoi) of South West Mau Forest (SWMF). Land use activities adjacent to these rivers and biodiversity disturbance on the riparian zone were identified and underpinned to changes on Total Nitrogen, Total Phosphorous, Potassium, Sulphur, Cadmium, Copper, Lead, Total Suspended Solids and soil Organic Carbon. Three sampling sites designated(upstream, midstream and downstream) were identified and established along each river as guided by existing land use activities represented by forest, tea plantation and mixed agricultural farming respectively. At each sampling site, a 200 m × 50 m section was systematically marked on each side of the river bank; the longest side being parallel to the river flow and divided into three belts transects each 20 m × 50 m, spaced 70 m apart. Six distinct land use activities (indigenous forest, food crop, tree and tea farming, livestock keeping and urban settlement) were identified as the major land use activities in SWMF. Plant species richness decreased and overall riparian disturbance increased from upstream (intact canopy with native vegetation) to mid-stream and downstream as epitomized by the structure, biodiversity disturbance resulting from extensive and intensive farming, intrusion of exotic species to livestock grazing and urban settlement. Variation among sampling sites in Total Suspended Solids, pH, Total Nitrogen, Phosphorus and Potassium were associated to different land use activities along the riparian zone. Total Nitrogen and water pH showed significant sensitivity to land use changes (p < 0.05). Put together these results indicate loss of biodiversity, riparian disturbance hence a need to adopt environmental-friendly land use planning and sustainable farming systems in SWMF.