In Catalonia, Spain, the wood properties and the quality of Cedrus atlantica (Endl.) Manetti ex Carrie Âre round timber was investigated on 120 sample trees from four stands with different spacings. The age of the sample trees lay between 25 and 36 y. The more wider-spaced trees show no relevant decline in quality as to anatomical and technological wood properties, but signi®cantly more timber volume and improved round timber quality. By means of wider spacing in the silvicultural treatment of Cedrus atlantica forests and regular selective thinning and pruning, the forest owners should be able to produce Atlas cedar of high sawn-timber quality.
Structural heartwood characteristics for Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C. Johnst., including a histometrical evaluation, were obtained by light microscopy coupled with a digitised image analysis system. The growth ring boundaries of the semi-ring-porous or diffuseporous wood are often marked by a marginal parenchyma band. Average fibre length is 975 μm, the fibres are thick-walled with a single cell wall thickness of 13 μm on average. Average diameter of the vessels which are arranged in non-specific patterns differs significantly between earlywood (116 μm) and latewood (44 μm). The topochemical distribution of lignin and phenolic deposits in the tissue was investigated by means of scanning UV microspectrophotometry (UMSP). Thereby, in heartwood tissue the deposition of extractives in vessels, pit canals, parenchyma cells, fibre lumina and partly also in the S2 layers of the fibres was detected. Monosaccharides were qualitatively and quantitatively determined by borate complex anion exchange chromatography. Holocellulose content is between 61.5 and 64.7% and Klason lignin content between 29.8 and 31.4%. Subsequent extraction of the soluble compounds was performed with petrolether, acetone/water and methanol/water by accelerated solvent extraction (ASE). Total extractives content in heartwood ranges between 14 to 16% on a dry weight basis. Major compounds in acetone/water extracts were identified as (-)-epicatechin, (+)-catechin and taxifolin, and quantitatively determined by liquid chromatography (RP-HPLC-UV).
Se determinó la durabilidad natural de la madera de Prosopis laevigata de cuatro sitios del Noreste de México mediante a) microcosmos terrestres (Pre-norma Europea 807) en un suelo tipo vertisol durante 32 semanas y b) en condiciones de laboratorio (Norma Europea 113 modificada) al exponer la madera a los hongos Coniophora puteana, Irpex lacteus, Pleurotus ostreatus y Trametes versicolor durante 16 semanas. La durabilidad natural fue cuantificada como pérdida de masa y pérdida de módulo de elasticidad dinámico (MOEdin). Adicionalmente, se determinó el efecto en el crecimiento de los hongos C. puteana y T. versicolor producido por los extractos de la madera de P. laevigata obtenidos por agua caliente, etanol y acetona en concentraciones de 100 partes por millón (ppm), 1 000 ppm, 5 000 ppm y 10 000 ppm. Los resultados indican que P. laevigata es altamente resistente en el microcosmos terrestre, con pérdidas en masa de (9 ± 2)% a (17 ± 5)% y MOEdin de (20 ± 4)% a (39 ± 11)%. En el segundo método, la pérdida en masa producida por los cuatro hongos fue de (0,7 ± 0,5)% a (2,6 ± 3,2)% y clasificada según la Norma Europea 350-1 como clase 1 (muy durable). La pérdida del MOEdin fue de (3,8 ± 4,2)% a (19,9 ± 5,6)%. Los extractos de P. laevigata obtenidos con agua caliente en concentración de 10 000 ppm mostraron el mayor porcentaje de inhibición al reducir el crecimiento de C. puteana (83 ± 8)% y (93 ± 6)% para T. versicolor.
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