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Mechanical properties of wood from the relict Abies pinsapo Boiss. Forest Product Journal. 59(10): 72-78.



Abstract: The mechanical properties of Abies pinsapo Boiss., a relict species from the south of Spain, have been studied very little due to the high level of protection that applies this species. Forest fire prevention measures have enabled the species to be characterized for the first time, including a comparison of its three regions of provenance (I. Sierra de Grazalema, II. Sierra Bermeja, III.Sierra de las Nieves). Tests were conducted using defect-free test pieces of small dimensions in accordance with the corresponding Spanish standard. In order to relate the findings to the wood anatomy, measurements were taken of tracheid length and diameter, tracheid wall thickness and number of rings per centimeter. The values per region of provenance (I, II, III) were: charpy impact strength 16.9±7.2, 12.4±3.7, 14.3±8.2 (J); MOR 74.9±19.3, 68.8±14.2, 71.1±22.0 (N/mm2); tensile strength perpendicular to the grain (tangential) 1.9±0.4, 2.0±0.4, 1.8±0.3 (N/mm2); tensile strength perpendicular to the grain (radial) 2.0±0.3, 2.0±0.2, 1.9±0.24 (N/mm2); splitting strength 2.4±0.2, 2.3±0.2, 2.3±0.2 (N/mm); compressive strength parallel to the grain 40.0±8.0, 39.9±7.9, 39.9±7.0 (N/mm2). The findings show that, in general the mechanical properties of wood from the three regions of provenance do not present statistically significant differences.

 

Adaptive anatomy of Pinus halepensis trees from different Mediterranean environments in Spain. Trees. Structure and function. 24: 19-30.



Abstract: A study was conducted on the variation in growth, biomass, juvenile wood anatomy and needle morphology of Pinus halepensis Mill. from three Spanish regions of provenance characterized by environmental differences, without the influence of the site factor. Seeds collected from two progenies in each region were planted in a single plot and the trees were felled at the age of seven years. The results showed significant differences between provenances, as well as the genetic or environmental influence on the traits analyzed. Trees adapted to moderate summer drought conditions (Inland Catalonia region) are primarily characterized by higher average values for height, diameter, biomass, cell wall thickness, inter-tracheid wall strength, membrane diameter, torus diameter, bordered pit aperture diameter, and ray tracheid abundance in comparison with trees adapted to severe summer drought conditions (Southern region and Balearic Islands region). The greater structural requirements of trees from the Inland Catalonia region, subjected to higher weight and wind loads, resulted in thick cell walls. Moreover, the large pits and more abundant ray tracheids in trees from this provenance would allow more efficient water transport and greater water storage capacity, respectively. The differences found between provenances suggest the adaptive nature of the anatomy of this species, which demonstrates the importance of the region of provenance when choosing reproduction material for reforestation.

 

Abies pinsapo forests in Spain and Morocco: threats and conservation. Oryx-The International Journal of Conservation. 44(2): 276-284.



Abstract: The conifer forests in the Mediterranean Arc have been subjected to overuse by humans since ancient times. Some species which took refuge in almost inaccessible places have managed to survive, but the area of other species has been greatly reduced as a result of agriculture, livestock raising, illegal felling and, in some cases, fire. The firs are no exception and today some species are little more than witnesses of the past. The Abies pinsapo forests are an example of this, as the last specimens of this species are found in just three enclaves in the south of the Iberian Peninsula and a further two in the north of Morocco. Until the middle of the 20th century, the pinsapo forests were subjected to major human pressure, and in Spain, they were under constant threat of overuse until they were acquired by the State. Many conservation efforts have been undertaken on both sides of the Strait of Gibraltar, and the fact that all the pinsapo forests are covered by some form of protection keeps them safe from the threat of inappropriate use and exploitation. The forests are now stabilised and are recovering after years of intensive grazing and use of their timber for construction, firewood and charcoal making. However, these relict forests face new threats such as climate change, arson and the appearance of pests. The limited area occupied by these forests makes them highly vulnerable to any disturbance.

 

Effects of burial of Quercus spp. wood aged 5910±250 BP on sorption and thermodynamic properties. International Biodeterioration & Biodegradation. 64: 371-377.



Abstract: The hygroscopicity and thermodynamic properties of buried Quercus spp. wood aged 5910±250 BP were studied and compared with wood of the same genus from recently cut trees. This was done by calculating the 35ºC and 50ºC sorption isotherms and fitting them in accordance with the GAB model. The thermodynamic parameters were obtained from the isotherms using the integration method of the Clausius-Clapeyron equation. Infrared spectra (FTIR) and X-ray diffractograms, respectively, were used to determine possible chemical modifications and changes in the crystalline structure of the cell wall.  The long period of time in which the wood was buried caused a decrease in the crystallinity index of the cellulose and a subsequent increase of amorphous zones with new areas of access for -OH groups. As a result, the equilibrium moisture contents of the buried wood are higher than in the recent wood, in both adsorption and desorption. In terms of the thermodynamic properties, the heat involved is greater in the buried wood than in the recent wood.

 

Use of artificial neural networks as a predictive method to determine moisture resistance of particle and fiber boards under cyclic testing conditions (UNE-EN 321). Wood and Fiber Science. 42(3): 335-345.



Abstract: Determining internal bond strength and thickness swelling after cyclic aging tests in humid conditions is essential in assessing the moisture resistance of particle and fiber boards. However, as operating procedures for these types of tests take at least three weeks, their use in daily finished product control is impracticable. To solve this problem an artificial neural network was used as a predictive method to determine these values from the board properties of thickness, density and moisture content in conjunction with thickness swelling and internal bond strength values obtained before the aging cycle. Using 113 boards, an artificial neural network was designed consisting of two separate feedforward multilayer perceptrons, applying the hyperbolic tangent as the transfer function. Training was conducted through supervised learning after the input data had been normalized. In the testing group the network attained a determination coefficient of 0.94 for the internal bond strength test and 0.92 for the thickness swelling test.

 

Esteban, L.G.

García Fernández, F.

de Palacios, P.

González Rodrigo, B.


2010

30

Esteban, L.G.

de Palacios, P.,

García Fernández, F.

García Amorena, I.


2010

Esteban, L.G.

de Palacios, P.

Rodríguez-Losada, L.


2010

29

Esteban, L.G.

Martín, J.A.

de Palacios, P.

García Fernández, F.

López, R.


2010

Esteban, L.G.

de Palacios, P.

García Fernández, F.

Ovies, J.


2009

28

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