Monika Barbara Gach

Understanding the regenerative capacity of Japanese knotweed (Reynoutria japonica Houtt.) is essential for developing effective management strategies. This study investigated how rhizome fragment diameter—classified as thin (≤ 1.0 cm), medium (1.1–2.0 cm), and thick (≥ 2.0 cm)—affects early sprouting. The one-way ANOVA and Tukey’s HSD post-hoc test revealed that sprout length increased significantly with rhizome diameter (p < 0.001), accounting for 62.40% of the variation in sprout growth. Specifically, thick fragments produced the longest sprouts (38.29 ± 1.70 cm), significantly outperforming medium (27.38 ± 1.43 cm) and thin (17.67 ± 1.76 cm) fragments. Despite these differences in vigour, resprouting frequency did not differ significantly between rhizome classes (p > 0.05), indicating that even the thinnest fragments retain regenerative potential. The hierarchical cluster analysis (HCA) further identified two functional clusters, separating thin fragments into a “survivalist” cluster characterised by reduced growth compared to medium and thick fragments, which form a “vigour-driven” cluster with a far superior regenerative potential. Moreover, these findings highlight a critical management loophole; that is, mechanical control alone may contribute to rhizome fragmentation, creating the impression of reduced infestations while viable fragments persist and regenerate following disturbance, a phenomenon termed the “latency period.” Thus, effective management must shift from strategies that merely fragment rhizomes to those that ensure the complete suppression of rhizome viability.

Invasive weeds threaten forest ecosystem sustainability worldwide, underscoring the need for non-chemical management strategies. To address this challenge, the present study investigated the short-term morphological response and survival of the Japanese knotweed (Reynoutria japonica Houtt.) rhizome sprouts subjected to 60-s electrocution at 0–180 V in 20-V increments. The one-way ANOVA showed no significant effect on sprout diameter (p > 0.05), whereas sprout length varied significantly (p < 0.05; η² = 0.540), with Tukey’s HSD post-hoc test revealing that mean sprout length ranged from 20.9 ± 2.1 cm to 42.6 ± 4.6 cm for sprouts subjected to 60 V and 180 V, respectively. In contrast, the Mantel–Cox trend test indicated a significant decline in sprout survival time with increasing voltage (χ²₍₁₎ = 29.028; p < 0.001), as reflected by the Kaplan–Meier analysis. Furthermore, the Cox proportional hazards model showed a 2.60% increase in mortality hazard per 1-V increase (HR = 1.026; p < 0.001). These results indicate that electrocution treatments of ≥100 V induce rapid sprout mortality, with complete mortality observed by day 3 at 100 and 180 V and by day 4 at 120–160 V, a response descriptively referred to as the “flash-kill” effect, and highlight survival analysis as a more informative indicator for evaluating R. japonica electrocution efficacy. Nevertheless, even though short-term sprout mortality is not a definitive measure of control, a long-term evaluation must account for rhizome reserve depletion, bud number and viability, as well as sprout reemergence under forest-oriented, field-scale studies.

Wildfires significantly affect wood properties and usability, yet their impact on hardwood species remains insufficiently understood. This study presents an exploratory characterization of moderately fire-affected pedunculate oak (Quercus robur L.) wood, combining physical, mechanical, chemical, and thermal analyses to evaluate depth-related changes within outer stem zones. Samples were collected from bark and from wood originating approximately 1 cm and 1–2 cm beneath the cambial region to evaluate radial variation associated with moderate surface fire exposure. The oven-dry density of fire-affected wood reached 720 kg·m⁻³, corresponding to values marginally below the literature reference ranges reported for unaffected oak wood. Bending strength decreased to 85.56 MPa, while compressive strength remained within or marginally above the literature reference (71.16 MPa), and Brinell hardness (42.75 MPa) stayed within the typical range for oak. Chemical and elemental analyses revealed degradation of polysaccharides and carbon enrichment in surface layers. FTIR and DSC analyses suggested partial hemicellulose degradation, structural modification of cellulose, and reduced thermal reactivity in outer stem regions. Despite these changes, the higher heating value (19.09–19.56 MJ·kg⁻¹) remained within the literature reference ranges reported for oak wood. The results suggest that under moderate surface fire conditions, fire-induced changes were primarily concentrated in outer stem layers, while inner wood retained properties comparable to the literature reference values for unaffected oak wood. These findings indicate that moderately fire-affected oak wood may remain suitable for selected material or energy-related applications following appropriate quality assessment and removal of thermally altered surface zones.

The tree-of-heaven (Ailanthus altissima (Mill.) Swingle) is one of the most aggressive arboreal invaders, threatening forest health and biodiversity across five continents. Given its rapid spread, severe ecological impact, and management difficulty, this paper (i) synthesises current knowledge of ecological factors driving its invasion in forest settings, (ii) critically evaluates available control methods, and (iii) proposes an integrated, evidence–based management framework suitable for forest ecosystems. Prevention strategies, such as legislation, vigilant monitoring, and the rapid removal of female trees, are essential first–line defences. For control, systemic herbicides applied via foliar sprays, basal bark, cut–stump, or stem injection methods provide the most effective long–term suppression. In contrast, mechanical or physical treatments alone often result in vigorous resprouting. Biological control agents show potential but remain purely experimental. However, the absence of approved biological agents and the limited availability of long–term cost–effectiveness data currently constrain management planning and large–scale implementation in forest ecosystems. This review presents a decision matrix that links control options to tree ontogenetic stages and site conditions, highlighting research needs that balance effectiveness, costs, and ecological safety. Overall, this synthesis offers a clear, evidence–based toolkit for managers and policymakers managing A. altissima in forest ecosystems.

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.

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.