Wood is a material of biological origin of fundamental importance for artisan and industrial uses. In outdoor environments, it is very attractive, but easily subjected to degradation. A valid alternative to chemical preservatives is thermal modification. The aim of this study is to evaluate ayous wood industrially subjected to thermal modification (215 °C) in order to emphasize the influence of heat treatment on selected physical and mechanical characteristics. As a result of the heat treatment, the physical and mechanical properties are generally reduced: the density in natural wood (TQ) was 379 kg/m3, in heat treated wood (TT) 319 kg/m3; the basic density in TQ was 327 kg/m3, in TT 299 kg/m3; the axial compression strength of TT was reduced by 18.1%; and the static bending strength of TT was reduced by 41.4% compared to untreated wood at 10% equilibrium moisture content (EMC). In addition, the samples, under the same environmental conditions in the laboratory, reached the equilibrium moisture content of 10% in TQ and 4% in TT.

High-temperature treatment of wood is a useful method for improving certain physical characteristics, ensuring durability without biocides, and improving the performance of wood when exposed to degradation agents. This work aims to determine the effects induced by a heat treatment performed industrially on ayous wood (Triplochiton scleroxylon K. Schum) from Cameroon, through the study of the main physical and mechanical characteristics. The heat treatment at 215 °C for three hours with a slight initial vacuum determined a reduction of the mechanical characteristics (compression strength 26%, static bending 46%, Brinell hardness 32%) and some physical properties (dry density 11%, basic density 9%), while it improved the behaviour towards variations of environment moisture. The anti-shrinkage efficiency was 58.41 ± 5.86%, confirming the increase of the dimensional stability. The darkening (ΔE 34.76), clearly detectable (L* 39.69 ± 1.13; a* 10.59 ± 081; b* 18.73 ± 1.51), was supported almost equally by both the lightness parameter (L*) and the a* chromatic parameter. The data collected during the laboratory tests were then subjected to statistical analysis to verify correlations between the characteristics examined. Statistical differences were highlighted between each physical and mechanical properties of ayous wood modified or not.

The wood characteristics due to weather conditions change over time, particularly the color that reflects chemical changes. Natural ageing is usually a relatively slow process; therefore, artificial ageing plays an important role in assessing the performance by shortening the time compared to natural weathering conditions. The aim of this research is to evaluate the color and reflectance variation of wooden surfaces due to artificial weathering obtained through a solar box chamber simulating outdoor conditions and subsequent water leaching. With the increase of weathering times, untreated specimen surfaces darken, whereas treated specimens lighten, so as to tend to have a similar color or in any case to decrease the chromatic difference that was at the beginning of the weathering tests. The measured values of conductance are higher in the leaching water of untreated specimens and tend to decrease after the first cycles. The values of pH range between 4.00 and 4.52 in untreated and treated specimens. FTIR spectroscopy demonstrated that water leaching caused loss of materials from the specimens, mainly from those thermally treated. FTIR spectra exhibit signatures of polysaccharide materials as main compounds. Bands of lignin and extractives are also visible. Water leaching seems to remove degraded surface microparticles of wood.

Wind in Europe is the main disturbing factor and the greatest damaging agent of forest stands, causing three times the annual damage caused by fires each year. The amount of trees destroyed by wind annually in Europe is over 38 million cubic meters. Given the importance and extent of the phenomenon of wind crashes, this has been one of the main topics on which forestry scientists have focused over time, so much so that already in the mid-1990s of the last century there were more than 200 scientific papers on this topic. However, most of these studies focused on the prediction of possible wind damage, paying attention to the population level and not to a single tree; moreover, almost all of the studies were carried out on conifers. Studies concerning the single tree have been carried out above all in urban forestry, where the trees live in unfavorable contexts and are very distant from what could be their optimal living conditions found in forests. The aim of this research was to search for possible correlations between the tree conformation and the crashes caused by windy events. This was in order to assess the characteristics predisposing trees to crash, in such a way as to provide the forest engineer with useful information in choosing the trees to take priority in order to reduce the damage caused by windy events. In conjunction with the “Vaia windstorm”, which affected much of Northern Italy, another meteoric event also occurred which caused the crash of numerous individuals inside the beech forest located on the summit of Monte Amiata, in Tuscany. On this occasion, an attempt was made to investigate the possible existence of single-tree scale indicators relating to a greater susceptibility to crash, in beech forests of the same age treated to shelterwood system, under the same phytosanitary, edaphic and topographical conditions. The research methodology applied is the same as in other studies carried out on the subject, in such a way as to allow comparison between the results obtained. Various parameters were analyzed, in particular: maximum height, crown insertion height, castle height, height corresponding to the maximum crown width, crown volume and surface. The findings showed that the main variables that had a significant influence on wind crashes were: tree height, crown surface and volume. In particular, the standing trees were taller than those crashed and with a larger crown.

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