In the presented study, the Sentinel-2 vegetation indices (VIs) were evaluated in context of estimating defoliation of Scots pine stands in western Poland. Regression and classification models were built based on reference data from 50 field plots and Sentinel-2 satellite images from three acquisition dates. Three machine-learning (ML) methods were tested: k-nearest neighbors (kNN), random forest (RF), and support vector machines (SVM). Regression models predicted stands defoliation with moderate accuracy. R² values for regression models amounted to 0.53, 0.57, 0.57 for kNN, RF and SVM, accordingly. Analogically, the following values of normalized root mean squared error were obtained: 12.2%, 11.9% and 11.6%. Overall accuracies for two-class classification models were 78%, 75%, 78% for kNN, RF and SVM methods. The Green Normalized Difference Vegetation Index and MERIS Terrestrial Chlorophyll Index VIs were found to be most robust defoliation predictors regardless of the ML method. We conclude that Sentinel-2 satellite images provide useful information about forest defoliation and may contribute to forest monitoring systems.

F. excelsior is affected by dieback in the major part of its natural geographical range in Europe, which results in economic and ecological losses. The disease is caused by the ascomycetous fungus Hymenoscyphus fraxineus, a pathogen introduced to Europe most probably from East Asia. This paper presents data on fungi identified on F. excelsior trees representing two different stages of ash dieback in Poland. Fungal communities were identified in initial necrotic lesions on living stems and twigs using the classical method of isolation on malt extract agar and morphological and molecular analyses. In dead apical parts of stems and twigs, fungi were identified by microscopic analyses of fruit bodies formed in situ. Seventy-one fungal taxa were found in 720 samples with symptoms of initial or advanced necrosis. The most common fungus detected in initial necrotic lesions in each forest site was Hymenoscyphus fraxineus (59.2 % of analysed samples). Other frequently isolated fungi included Alternaria alternata, Diaporthe eres, Diplodia mutila, Fusarium avenaceum, F. lateritium and Phomopsis spp. Fruit bodies on dead apical parts of stems and twigs were produced mostly by Diaporthe eres, Diplodia mutila, Lophiostoma corticola, Phomopsis spp., Sirodothis sp. and Valsa cypri. Fungal communities from different sites were similar, as shown by high Sørensen similarity index values. Greatest variation in fungal community structure at the initial necrotic stage was realized by D. mutila and F. avenaceum, and at the advanced necrotic stage by D. eres, D. mutila and Phomopsis spp. Data show a close affinity of certain fungi to site, suggesting geographical relatedness. The ecological effects of distribution of the invasive H. fraxineus and of other fungi sporulating on diseased ash trees in Europe are discussed.

This paper reports the results of the study on the new type of necrotic lesion observed on epicormic shoots and leaf petioles of Fraxinus excelsior showing ash decline symptoms in stands of the Miechów Forest District, southern Poland. The performed symptom analysis included: shape and size of necroses, discoloration of necrotic tissue and the occurrence of fungal fructification. The same species of fungus, which was initially identified as Boeremia exigua, was isolated from 97% of epicormic shoots and from 82% of leaf petioles. However, detailed morphological and physiological (NaOH test) analyses and combined ITS, ACT, TUB and EF1-α phylogeny proved these isolates to belong to Boeremia lilacis, the species known so far as Syringa vulgaris pathogen occurring occasionally also on Forsythia hybrids or Philadelphus. Fraxinus excelsior is reported for the first time as a host for this fungus. To clarify the possible role of B. lilacis in development of necrotic lesions on ash, 10 randomly selected isolates were tested for their pathogenicity toward young F. excelsior plants using the method of artificial wound inoculation under field conditions. The isolates used in the test caused tissue necroses on all 60 inoculated shoots and all 60 inoculated leaf petioles. Necrotic lesions developed as a result of artificial inoculation corresponded largely to the symptoms following natural infections.

This study addresses the relationships between the foliage and bark area of Norway spruce (Picea abies) branches left in the forest after managing large timber: the densities of infestation by Pityogenes chalcographus, Pityophthorus pityographus and Dryocoetes autographus; and the reproductive efficiency of P. chalcographus. Based on the models developed in this study, a positive correlation was found between the foliage area of spruce branches and the densities infested by P. chalcographus and D. autographus, though a higher negative correlation was found in relation to the size of the branch bark area (BA) and the infestation densities. A negative correlation for the branch BA was also found on P. pityographus. This result shows that the desiccation of branches affects the infestation densities of bark beetles. In contrast, the size of the branch BA was positively correlated with the reproductive efficiency of P. chalcographus, with higher reproductive efficiency on the branches from the outer layer of the pile than on disorderly scattered branches on the ground.

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.