The aim of this research was to determine the survival rate, dimensions, and wood quality of black locust, ash-leaf maple, common maple, and American ash introduced to the landfill of the “Adamów” Power Plant as part of the reclamation process. The experimental area consisted of 13 research plots. On the three plots where the trees were planted directly into the ash, the trees completely collapsed. As a result of this research, it was found that the black locust had the best survival rates, whereas the American ash had the worst. The black locust and ash-leaf maple reached larger sizes on the plots where the ashes were covered with a 50-centimetre layer of sewage sludge (S50) or with a 50-centimetre layer of clay (C50), while the common maple grew the largest on the plots where a 25-centimetre layer of sewage sludge (S25) was used. Our research shows that about 40% of the examined species of wood were of good quality (Q1, Q2), which in the future will make it possible to obtain sawmill raw material. On the other hand, lower quality wood (Q3, Q4), which accounted for over 50% of the assessed wood material, can be successfully used as a biomass for energy purposes.

The aim of the study was to assess the hardness and compressive strength of oak wood from various historical contexts, and to compare these properties with modern oak wood. The study utilized both radiocarbon and dendrochronological dating to determine the age of the wood. A total of five oak wood fragments analyzed i.e. bog oak, oak wood from the bell tower of the Collegiate Basilica of the Holy Spirit in Przeworsk; oak wood from the scaffolding of the St. Nicholas Church in Gniew, wood from a dismantled granary in Drawsko Pomorskie and sample from a water dam in Czaniec. The dating confirmed that the oak fragments varied in age, ranging from several centuries to over 900 years. The mechanical tests using the Brinell method and compressive strength tests indicated that wood of bog oak displayed statistically significant differences in compressive strength compared to the other wood samples, which could be attributed to the long-term mineral saturation of the wood from prolonged exposure to anaerobic conditions in the bog. This mineralization likely caused a reduction in its elasticity and overall strength. In contrast, other samples, which had been exposed to varying environmental conditions like periodic water immersion or protection from moisture, did not show significant differences in mechanical tests. Despite these challenges, the findings suggest that compressive strength could serve as a useful indicator for estimating the age of oak wood in archaeological contexts, particularly for assessing the influence of long-term environmental conditions on wood properties.

Under investigation three deadwood landing yards were established - two with pine wood and one with spruce wood. Three measuring baskets were placed on each landing yard. In each basket round timbers were arranged in three test layers. In each test layer, 7 round timbers were arranged. Two cross-sections were photographed on each roller. Photographs obtained during successive trials were analyzed with the MultiScan program. Measurement work was conducted 12 times, at the beginning (month 0) and then at intervals of 6, 9, 12, 15, 18, 24, 30, 36, 42, 48 and 54 months. It was found that blue stain became invisible on the cross-sections of pine round timbers after 12 months and in spruce after 6 months. On the cross-sections of pine round timbers, it was observed that hard rot appeared only after 9 months. In spruce wood, the presence of hard rot was already evident from the month 0. In most cases, the largest areas of hard rot were found in the upper layers. In the case of soft rot on pine wood, only after 12 months were isolated cases of its occurrence recorded and in spruce wood after 6 months. After 24 months did the number of cross-sections with this rot increase sharply. Natural depreciation processes of wood raw materials due to long storage cause negative changes in its quality. However, these changes are not significant, meaning that after 54 months of the raw material being in storage, it is still mostly a full-value raw material.

Understanding the impact of reclamation measures on the quality of timber produced in post-mining areas is crucial for the proper establishment of future forest cultures on such sites. We studied European larch trees (Larix decidua Mill.) grown since 1981 on the external dump of a brown coal mine in Bełchatów (Central Poland). In particular, the effects of stand admixture and the intensity of mineral fertilization, applied in the initial phase of tree growth, on the increments and quality of larch wood were evaluated. Total tree height and stem diameter of 4-meter sections were measured. Qualitative timber classification took into account the share of wood defects, which excluded the timber from a higher quality-dimensional class. Larch trees grown in a monoculture had a better quality of wood compared to larch grown mixed with other species. Fertilization, applied in the initial afforestation period, had only a limited effect on the growth of larch trees. Curvature and knots determined timber quality most significantly. While knots had a decisive importance in larch growing in the monoculture stands, curvature determined wood quality in the admixed larch stands.

Wildfires are becoming more frequent in Central Europe, raising questions about the mechanical and chemical integrity of fire-affected conifer wood. Because commercial species such as silver fir (Abies alba), Norway spruce (Picea abies), and Scots pine (Pinus sylvestris) are not evolutionarily adapted to fire, their thermo-mechanical response remains poorly quantified. This study investigates oven-dry density, static bending strength, compressive strength parallel to the grain, Brinell hardness, chemical composition, elemental composition, and heat of combustion of wood collected from a recent post-fire stand in Poland. Fire exposure resulted in a slight reduction in oven-dry density, while compressive and bending strengths increased relative to reported reference values, likely due to moisture depletion and partial thermal modification of cell-wall polymers. Chemical analyses showed moderate thermally induced shifts, including higher lignin and carbon content with depth, consistent with progressive carbonization of the affected tissues. Although surface-affected wood retained measurable mechanical capacity and energy value, its structural applicability remains constrained by potential brittleness and the limited sampling depth. These findings provide essential baseline data for evaluating post-fire conifer wood and its potential use in low-grade material and bioenergy applications.