One of the characteristic features of forestry work is its seasonality. Most of forestry work comprises simple activities not requiring any special preparation from the workers who do it. However, the current state of forest technology makes it possible to perform many operations, using machines and technical equipment. In Poland, the type of work that is used most often is manual work. It is still relatively cheap and available. Most of the companies providing services for forest management departments just use this simplest form of performing tasks and hire so-called seasonal employees to perform them. Thanks to this solution, the costs of keeping employees in the event there is a seasonal fall in demand for their services, is eliminated. The principal purpose of the research undertaken is to propose technological and organizational solutions that would diminish the impact of natural seasonality of forestry work on the level and structure of employment in the forestry service companies. The initial analyses show that by increasing the degree of work mechanization the demand for employees performing tasks in a forest management department may be reduced even by several tens of persons per month.

The aim of this study was to analyse the frequency and extent of mechanical damage of tree stems in mountain spruce stands of varying forest cover index and ground slope, without taking into account the technology used in obtaining wood. The study was conducted in 17 spruce stands located in the Sudetes and the Carpathians. In the stands the 1 ha test surfaces were established. The damage on trees with dbh ≥ 18 cm was measured. As a result of the analysis it was found that the most damaged trees grew in the stand with forest cover ratio of 0.7 and 1.0, while taking into account the decline of the area most damage was found in the stands with a slope of 16 to 25°. The study, however, showed no clear relationship between the position of necrosis on tree stems (its size and height) and forest cover and a decrease of the area.

Machine timber harvesting makes it possible to reduce substantially factors which have adverse impact on human health and which accompany manual-machine timber harvesting, presently predominating in Poland. The ergonomic factors classified into four following groups may be recognised as the main preconditions related to work with multi-operation machines: physical load – small energy expenditure, a very high value of repetitiveness and static efforts; mental load – high level of monotony, aesthenopia, a high level of stress; environmental load – significant limitation of hazard to operator’s hearing, work under conditions of thermal comfort, reduced vibration hazard; organisational load – a relatively low risk of work – related accidents, making it possible to perform work operations throughout the year, continued employment, high work autonomy, independence in decision making, a possibility for workers to organise themselves and form work teams. The paper presents subjective perceptions and opinions of fifty operators of specialised machines with respect to their work load. Almost a half of the respondents worked over 50 hours per week. One third found their work conditions difficult. Work pace was recognised as particularly challenging to their well-being as merely 6% of respondents found it relatively low. Additionally, the selected elements of assessment of workstations under study in terms of energetic costs and noise load is discussed The maximum energy expenditure of a machine operator is related to operations performed outside a cab: tuning up, routine maintenance, and repairs. Energy expenditure related to work inside a cab did not exceed 14 kJ/min. Noise level in a low-noise cabin was lower than sixty dB(A). Use of machines to a large degree eliminates important health-adverse factors accompanying combined machine-driven and manual timber harvesting, however, it creates conditions favouring occurrence of new ailments and diseases, totally different from those which have been recorded so far in forestry.

In the last two decades the amount of timber harvested in Poland has almost doubled. On the other hand, in some regions of the country a decrease in the number of people willing to work in the forest can be observed. In such a situation, multioperational machines like harvesters and forwarders are being more frequently used in skidding and logging process. These machines operate mainly in the short-wood system, in which large- and medium-sized timber is bucked out of the butt part of the stem in form of logs, while in four of sections in the top part. Buyers are reluctant to buy cut-to-length (CTL) timber because of the widespread belief that timber produced as logs has a greater volume in comparison with longwood one. This paper presents preliminary results of research on CTL logging of large-sized pine longwood timber. Volume and value of timber provided in form of longwoods and logs were compared. The study was conducted in The “Lasy Mazurskie” Forest Promotional Complex (N Poland). The analysis showed that volume of CTL timber is usually smaller compared with the longwood one by a few percent, while the value is larger by several percent.

Fungi play an important role, as by decomposing dead organic matter they contribute to the carbon cycle in nature. Apart from this beneficial effect, fungi in forest ecosystems cause diseases of deciduous trees. Stumps, being remnants of stems left after felled trees, provide nutrient resources for various organisms, including fungi causing the most dangerous diseases of forest trees such as Armillaria root rot or Heterobasidion root rot. Colonisation of stumps is determined by three major factors, i.e. microhabitat, availability of nutrients and occurrence of other competing organisms. The primary aim of this study was to prepare an inventory of fruiting bodies of fungal species found on stumps in selected subcompartments of the Zielonka Experimental Forest Division, to present fungal species diversity in the analysed area and to identify factors determining the occurrence of fungi in the investigated area as well as those determining the intensity of stump colonisation by fungi. Results indicate that fruiting bodies were found less frequently on pine stumps than on stumps of deciduous species. The most abundant fungal species in terms of population size observed on stems in the analysed areas were Trametes versicolor (191 localities), Schizophyllum commune (136 localities) and Stereum hirsutum (130 localities). A vast majority of species reported in the analysed areas have a positive effect on the forest ecosystem.

Logging is an important element of wood production. Its modelling gives an opportunity to compare different scenarios before the work has started and may be helpful in future operations planning. A computer program was created which includes basic factors influencing forwarder efficiency: parameters of the machine, the stand and the assortments. The results of the simulation confirm relations between certain factors and forwarder performance given by other authors. Counted absolute values may be higher than real. Relative comparison of relations between factors is more accurate.

The paper presents a comparative analysis of wood calorific value of grand fir (Abies grandis Lindl.), originating from four stands of the southern Poland. The research material were the samples, collected from the trunks of 30 trees in each stand. The samples were divided into sections, each containing five annual increments. Then each section was measured: annual ring width and the relative wood density, which was converted to dry wood density, taking the total volumetric shrinkage of 11%. It was assumed that the calorific value of 1 kg dry wood of grand fir is 20.15 MJ. On the basis on the analysis it was found that the average calorific value of 1 m³ of grand fir wood was 8021 MJ. It was shown, that a significantly higher calorific value was obtained by the combustion of 1 m³ wood of giant fir trees, growing on the poorer soil in comparison to the more fertile soils. Statistical analysis also showed that with increasing age of the trees the calorific value of 1 m³ grand fir wood increases significantly.