Luis García Esteban

Variation in wood anatomical traits of Pinus sylvestris L. between Spanish regions of provenance

The Spanish populations of Pinus sylvestris L. occupy differentiated sites and must therefore include structural variations to cope with varied climate conditions. This study compares wood anatomical traits of P. sylvestris from ten Spanish regions of provenance with contrasting climates, taking into account the effects of region of provenance and tree nested within provenance on variation in wood biometry. In general, the effect of both sources of variation (provenance and tree) on wood biometry was highly significant. Most of the anatomical variations observed were intra-populational (at the tree level), although variation explained by provenance was high for some parameters (e.g., ray frequency and ray parenchyma cell frequency), suggesting high environmental influence. Trees in the driest region, growing in a Mediterranean phytoclimate, were characterized by large tracheid lumens, suggesting more efficient water conduction. They also had thick cell walls, which would reduce the risk of cavitation caused by high implosion stress during periods of drought, as well as a high ray tracheid frequency, implying greater water storage capacity in the sapwood. The population with greatest growth, located in an oroboreal phytoclimate, was characterized by large bordered pits and long tracheids, which would reduce resistivity in water transport. At higher altitudes, tracheid lumen diameter and resin canal diameter tended to be smaller, and intertracheid wall strength was greater. Results are discussed in relation to adaptation of the species to growth demands and frost.

Bordered pit and ray morphology involvement in elm resistance to Ophiostoma novo-ulmi

The main objective of this study was to identify differential anatomical features between Ulmus pumila L. and Ulmus minor Mill. clones resistant to Dutch elm disease and U. minor clones susceptible to Dutch elm disease, with a focus on the intervascular pits and medullary rays. Resistant elms showed lower mean values than susceptible elms for pit membrane diameter, pit aperture area, pit membrane abundance per vessel-wall area, ray width, and ray tangential area. A principal component analysis of the parameters measured revealed slight differentiation between species but clearly grouped U. minor clones according to their susceptibility group. In comparison with susceptible elms, the pit structure observed in resistant elms may limit passive fungal spread within the sapflow, lower the probability of fungal cells passively reaching pit membranes, and reduce the vulnerability of the xylem to cavitation. Similarly, the ray structure observed in the resistant elms is likely to reduce the amount of easily acces...

Prediction of plywood bonding quality using an artificial neural network

Abstract The bonding quality test is one of the most important of all tests performed on plywood, because it determines the suitability of boards for use in the type of exposure they are intended for. Because this test involves aging pretreatment, results are not available in <24–97 h after manufacture, depending on the type of board, and therefore any error in the manufacturing process is not detected until 1–4 days later. To solve this time problem, an artificial neural network was developed as a predictive method to determine the suitability of board bonding through other properties that can be determined in less testing time: thickness, moisture content, density, bending strength, and modulus of elasticity. The network designed WAS a feedforward multilayer perceptron trained by supervised learning after normalization of the input data, and allowed the bonding test result to be predicted with 93% accuracy.

Sorption and thermodynamic properties of juvenile Pinus sylvestris L. wood after 103 years of submersion

Abstract The hygroscopicity and thermodynamic properties of juvenile Pinus sylvestris L. wood taken from the submerged piles of a bridge built in 1903 over the Jiloca River, in Spain, were compared with the corresponding values of juvenile wood of the same species from recently cut trees. The 35°C and 50°C isotherms were plotted and subsequently fitted using the Guggenheim-Anderson-Boer-Dent method, and the isosteric heat of sorption was obtained through the integration method of the Clausius-Clapeyron equation. The isotherms were compared by means of the hysteresis coefficients. Infrared spectra were recorded to study the chemical modifications, and the crystal structure of the cellulose was studied by X-ray diffractograms. The submersion in water resulted in hemicellulose degradation and a decrease in the crystallinity index and the crystallite length, accompanied by a corresponding increase in the proportion of amorphous zones. Owing to this, the equilibrium moisture contents of the water logged wood are higher than in the recent wood, both in adsorption and in desorption. In terms of the thermodynamic properties, the bond energy is higher in the recent wood than in the water logged wood.

Influence of region of provenance and climate factors on wood anatomical traits of Pinus nigra Arn. subsp. salzmannii

Region of provenance is defined as an area with uniform ecological conditions where stands with similar phenotypic or genetic features are found. This study assesses the effect of differing climate conditions of eight Spanish regions of provenance of Pinus nigra Arn. subsp. salzmannii on earlywood anatomical traits measured in samples from basal discs from mature trees. Results showed that variation in wood biometry between provenances was high and more pronounced than intrapopulation variation. When comparing P. nigra with other Mediterranean pines, high intertracheid wall strength values are associated with better adaptation of pines to arid conditions. However, the intraspecific variations of this parameter in P. nigra did not follow the same pattern, due to the influence of mechanical support requirements. Trees subject to greater aridity were characterised by short tracheids, apparently resulting from their poorer growth, and high frequency of rays and ray parenchyma cells, which would allow trees to store greater amounts of starch, which is the source of metabolites invested in minimising the limitations imposed by water stress. Severe winter cold spells were strongly associated with high axial resin canal frequency and large radial resin canals, creating a powerful, preformed defence system. Increased tracheid lumen involved an increase in the size of bordered pits, favouring sap flow between tracheids, in addition to an increase in the maximum diameter of cross-field pits, favouring the flow of water and metabolites between the axial and radial systems. The high influence of region of provenance on structural variation in P. nigra shows the importance of provenance in the selection of seed origin for reforestation.

Artificial neural networks in wood identification: the case of two Juniperus species from the Canary Islands.

Neural networks are complex mathematical structures inspired on biological neural networks, capable of learning from examples (training group) and extrapolating knowledge to an unknown sample (testing group). The similarity of wood structure in many species, particularly in the case of conifers, means that they cannot be differentiated using traditional methods. The use of neural networks can be an effective tool for identifying similar species with a high percentage of accuracy. This predictive method was used to differentiate Juniperus cedrus and J. phoenicea var. canariensis, both from the Canary Islands. The anatomical features of their wood are so similar that it is not possible to differentiate them using traditional methods. An artificial neural network was used to determine if this method could differentiate the two species with a high degree of probability through the biometry of their anatomy. To achieve the differentiation, a feedforward multilayer percepton network was designed, which attained 98.6% success in the training group and 92.0% success in the testing or unknown group. The proposed neural network is satisfactory for the desired purpose and enables J. cedrus and J. phoenicea var. canariensis to be differentiated with a 92% probability.

The Wood of Pinus Canariensis and Its Resinous Heartwood

Pinus canariensis (Canary Island Pine or Piteh Pine) forms natural forests on the islands of Tenerife and La Palma. The heartwood has an extraordinarily high resin eontent, and this paper provides an anatomical deseription of the wood as well as an interpretation of the faetors relating to this resinifieation

Abies pinsapo forests in Spain and Morocco: threats and conservation

The conifer forests of the Mediterranean Basin have been subjected to overuse by humans since ancient times. Some species have survived in inaccessible refuges but the ranges of other species have been greatly reduced by the effects of clearance for agriculture, livestock raising, illegal felling and, in some cases, fire. The firs are no exception and some now exist only as relict species. Abies pinsapo is an example, with the species surviving in only three enclaves in southern Spain and two in northern Morocco. Until the mid 20th century A. pinsapo forests were subject to major anthropogenic pressures, and in Spain they were under constant threat of overuse until they were acquired by the State. Conservation efforts have now, however, been undertaken in both Spain and Morocco, and the fact that all the A. pinsapo forests are covered by some form of protection preserves them from further inappropriate use or exploitation. These forests are now recovering after years of intensive grazing and use of their timber for construction, firewood and charcoal making. However, these relict forests face the new threats of climate change, arson and the appearance of pests. The limited area occupied by these forests makes them highly vulnerable to disturbance.

Comparative Anatomy of the Wood of Abies Pinsapo and Its two Moroccan Varieties

This study describes the structure of the wood of Abies pinsapo from samples taken from its three natural distribution areas in the Iberian Peninsula (Sierra de Grazalema, Sierra de las Nieves and Sierra Bermeja) and compares them with the varieties from the north of Africa, Abies pinsapo var. marocana from the Talassemtane mountains and A. pinsapo var. tazaotana from the Tazaout mountains. All the samples were collected in their regions of provenance. To put the results into perspective, a comparison was also made with the wood of Abies alba and A. numidica. The wood of the Iberian A. pinsapo and of its two varieties from the Rif mountains in Morocco is anatomically similar, and there are no qualitative differences that enable the wood to be differentiated except for the presence of resin deposits in the tracheids adjacent to the rays in the samples from Grazalema. Quantitatively, for tracheid diameter and tracheid length there are statistically significantly differences (p<0.05) between those of Spanish provenance and the Moroccan varieties, but for tracheid pit diameter, largest diameter of cross-field pits and tall ray frequency the samples from Sierra Bermeja have more in common with the African samples.

Sorption/desorption hysteresis revisited. Sorption properties of Pinus pinea L. analysed by the parallel exponential kinetics and Kelvin-Voigt models

Abstract The hygroscopic properties of Pinus pinea L. wood at 35 and 50°C were investigated by the dynamic vapour sorption (DVS) technique. The sorption kinetic behaviour was studied through the parallel exponential kinetics (PEK) model, which is subdivided into a fast and a slow process. The parameters obtained by PEK were interpreted based on the Kelvin-Voigt (KV) model to determine elasticity and viscosity values of the wood cell wall. The PEK data perfectly fit the experimental data. The temperature-dependent transition between the fast and slow processes is fluent. The slow process contributes more to the total hysteresis of sorption. The kinetic properties varied in relation to the type of cycle and the temperature. The moduli of elasticity and viscosity were higher in the slow process than in the fast one. In both processes, the moduli showed a decreasing tendency in relation to relative humidity.