Wood is a material that is widely used in many applications but it has some weak properties which can be modified with various solutions. The aim of this study is to examine how preservatives affect wood properties. The effects of preservatives are classified into five categories: mechanical properties, weathering, moisture resistance, biological durability and fire resistance. The different properties have been studied at varying intensity in wood science – for example moisture resistance and biological durability have been studied quite a lot, while weathering is a rather new issue. Preservatives have a minor effect on wood, depending on the solution, treatment, and wood species, but generally preservatives cannot cause dramatic changes to the properties of wood, whereas the moisture content has a great effect on the characteristic of wood. In addition to the properties of wood and the weight percentage gained after modification, the crucial properties of modifiers are for example the pH value and the comparison between water- and oil-based solutions.

Key words: wood, modification, property, preservative

Recreation in forests is a very important service provided by the environment that allows to generating considerable incomes for the local population. To make appropriate management strategies, recreational values of the forests have to be considered in order to lose the landscape and the other factors of tourists’ attraction. Forest recreational values - due to the lack of a market - can be estimated through environmental evaluation techniques such as Contingent Valuation (CV), Choice Experiment (CE) or Travel Cost Method (TCM). The first part of the paper offers a meta-analysis of the recreational values of mountain forests in Europe in order to compare the values of similar sites for altitude (above and below 1,000 m a.s.l.), tree species composition (mixed and pure conifer/broadleaved forests) and tourists target. In the second part of the paper, a Benefit Transfer (BT) application is presented by applying the results of the meta-analysis (average value transfer). The “policy” site chosen is an Alpine valley located in the north-east of Italy (Valle di Non, Province of Trento). The results of meta-analysis highlight that the recreation value of the mixed forests is higher than that of pure forests (conifer or broadleaved forests), while the applied economic techniques (CV or TCM) has low influence on the recreational value per visit. Finally, the results of the application show that the total recreational value of the Valle di Non forests is around 2,5 million € per year and it has a considerable weight in the Total Economic Value (TEV) of the valley’s forests.

Key words: mountain forests, tourism and recreation, economic evaluation, Benefit Transfer method.

This study defined the productivity levels of a CBI 5800 grinder using a truck as a base machine for processing stumps, logging residues and whole trees at a roadside landing. For defining the solid content of the truck loads, the weight of each load was recorded. Furthermore, samples from each load were collected in order to define the moisture content, dry green density, green mass, particle size distribution and ash content of processed raw material. The solid content of the chip loads was based on the relation of the recorded dry masses, dry green densities and frame volumes of each load. The time study was conducted using a hand-held field computer by means of continuous timing, where the clock is running continuously and the different work elements are separated from each other. The effective hourly productivity (E0h) of the operation was presented per solid and loose volumes (m³), green and dry mass (kg), and the energy content (MWh) of the forest chips. Furthermore, the noise and vibration of the grinding operation were measured.

The effective hourly productivity of grinding was highest for logging residues (loose volume, 224 m³/E0h & solid volume, 81 m³/E₀h). The productivity of whole tree grinding was second highest (loose volume, 198 m³/E₀h & solid volume, 60 m³/E₀h) and the lowest productivity (loose volume, 131 m³/E₀h & solid volume, 36 m³/E₀h) was in stump grinding. Based on dry masses the productivity of grinding logging residues was 29022 kg/E₀h. The productivities of grinding whole trees and stumps were 24958 kg/E₀h and 17315 kg/E₀h. The effective hourly productivity of grinding logging residues based on energy content was 135 MWh/E₀h and respectively for whole trees 119 MWh/E₀h. For stumps free of mineral soil, the productivity was 85 MWh/E₀h and for stumps of the time study experiments with mineral soil 72 MWh/E₀h, respectively.

Based on the results of this study, it can be concluded that the CBI 5800 grinder (power 462 kW/620 hp) works well for grinding logging residues, split stumps and whole trees at a roadside landing. Moreover, the grinder was consistent in terms of interruptions caused by impurities in the raw material. The bulk density of chips based on grinding was lower than the bulk density of conventional chips. The productivity of the studied grinder was significantly better compared to conventional drum chippers at the same size category when comminuting logging residues at the roadside landing. The grinding productivity of whole trees was slightly lower or at the same level than when performed by drum chippers with a truck as a base machine. The productivity of the CBI 5800 grinder was significantly lower when compared to large grinders used in terminals and end use facilities. However, the productivity was three times higher compared to the pre-grinding of stumps with slow-running grinders at the roadside landing.

Key words: stumps, logging residues, small diameter wood, comminution, chip dimension, noise, vibration, heating value.

For fast detection of wood moisture content (MC), handheld resistance-type and capacitance-type electrical moisture meters are widely used. In moisture contents above the fibre saturation point (FSP), the measuring accuracy and precision of resistance-type moisture meters starts to progressively decrease as the wood MC increases. The aim of this research was to quantitatively explore this well-known qualitative trend. Three different resistance-type wood moisture meters from leading manufacturers were compared. The display readings of the moisture meters were compared by using the absolute MCs determined for relevant specimens with the oven-dry method. The specimens with the dimensions of 100x60x60 mm (length x width x thickness) were made of three different tree species (black alder, birch, aspen); a total of 60 specimens per each tree species were used. The specimens were dried in a climatic chamber under equal conditions (32°C and 98% RH) until the desired MC was achieved. All wood MC measurements were conducted at a room temperature of 20°C.

Modelling of experiment data confirmed the progressive increase in the absolute error in a single measurement of wood MC with resistance-type moisture meters as the average absolute MC rose. Based on the model, the absolute error on the same confidence level (95%) and for the average MC of 27% was ± 3.9% MC, for the average MC of 60% it was ± 10% MC, and for the average MC of 97 % the absolute error was ± 17.5% MC. The best prediction error in wood average MC predicted on the basis of the same model was ± 1.12% MC. The same model was used to predict the resolution of resistance-type moisture meters for the above-mentioned average MCs, which was found to be approximately 1% MC.

Key words: wood drying, wood moisture meter, above FSP.