Abstract: Common juniper Juniperus communis L. formations occurring on oligotrophic sandy substrates in central European lowlands are of high ecological value, but although once widespread, they have disappeared over most of Europe. In suboceanic areas of Central Europe, the Vaccinio−Juniperetum communis Passarge & G. Hofmann 1968 association is recognized. In addition, the Helichryso−Juniperetum association was published by Barkman as its subcontinental vicariant, occurring in central and north−eastern parts of Poland. However, according to the International Code of Phytosociological Nomenclature – ICPN, the vicariant was not valid due to insufficient phytosociological documentation. In Poland, common juniper shrub patches are usually recognized as a plant community with Juniperus communis. The phytosociological classification of plant communities in Europe identifies the Vaccinio−Juniperion communis Passarge in Passarge et G. Hofmann 1968 alliance, containing European lowland juniper scrub communities. Lowland juniper patches are protected as Natura 2000 habitat type 5130. However, the subcontinental vicariant does not have a valid phytosociological indicator. This article’s aims are to document new patches of subcontinental juniper scrub, validate the Helichryso−Juniperetum association identified by Barkman, describe the internal variation of the syntaxon, and provide an overview of the distribution of juniper scrub and its dynamics in central and north−eastern Poland. To accomplish these objectives, study sites were established in the Nowa Warszawa Forest (NWF), located on the edge of Warsaw, and in the Niepust range in Kampinos National Park (KNP). Fieldwork was conducted in 2021. Juniper scrub was documented with 17 relevés. The old association name was not considered applicable due to the low frequency of Helichrysum arenarium and its absence in the designated type. Thus, Solidagini virgaureae−Juniperetum communis was instead typified. The diagnostic value of species differential at the association level was reviewed by comparing species frequencies with the synoptic table of Vaccinio−Juniperetum from Mecklenburg−Vonpommerns. Two new subassociations and a third provisional subassociation were distinguished and typified. The S−J cladonietosum mitis is characterised by a large share of grassland species, higher than in the S−J typicum. The provisional S−J molinietosum caeruleae is characterised by the presence of Molinia caerulea. The large number of species differential at the association level within the subassociations indicates that they all belong to Solidagini virgaureae−Juniperetum communis. In our opinion, they should be included in the 5130 Natura 2000 habitat type. Juniper scrub formations are rapidly declining in central and north−eastern Poland. Their active conservation has already started in the Ciosny nature reserve and KNP.
Key words: Helichryso−Juniperetum, Juniperus communis, lichens, Natura 2000, 5130 habitat, Warsaw, Kampinos Forest

Abstract: In this study we investigated if near infrared (NIR) spectroscopy can be effectively used to predict content of various fraction (LF – light fraction and MAF – mineral associated fractions) of soil organic matter, also in the context of their spatial distribution. Additionally, we used NIR spectroscopy to evaluate basic properties of forest soils. We analyzed 256 soil samples from the topsoil of plots in central Poland. Using laboratory techniques, we divided the soil samples into two soil carbon fractions: the light fraction (LF) and mineral−associated fraction (MAF). A calibration model was developed using the spectra from 171 soil samples and their corresponding measured values. The regression model was validated using 85 independent soil samples. Using this model, we estimated the following forest soil properties: carbon concentration in light fraction (C_LF), carbon concentration in mineral−associated fraction (C_MAF), ratio of the C_LF to the total carbon content of the soil sample (C_LF/C), ratio of the C_MAF to the total carbon content of the soil sample (C_MAF/C), the total concentration of carbon (C_t) and nitrogen (N_t), C:N ratio (CN), pH, the concentration of exchangeable base cations (BC) and cation exchange capacity (CEC). The best calibration results were obtained for C_LF, C_LF/C and C_MAF/C. The largest adjusted coefficients of determination for validation were obtained for N_t, CN, BC and CEC. Model developed forthe C_LF was characterized by inaccurate value prediction. The paper shows also the relationship between the optimum number of soil sample spectra and the absolute and relative measurement error. Comparison of the measured and predicted values show that NIR spectroscopy has potential for determining soil parameters. The statistical assessment and spatial distribution analysis of the modelled C_MAF demonstrated relatively good agreement with measured values. However, the model’s assessment of the C_LF was less accurate. We conclude that NIR spectroscopy is most applicable for use in soil science to determine the parameters: C_t, N_t, C/N, pH, CEC, C_MAF and C_MAF/C.
Key words: forest soils, near infrared spectroscopy, soil analysis, soil fraction, soil organic matter

Abstract: Due to the spatial distribution of forests and their area, there is currently no monitoring of society’s activities in forests on a large scale. However, the high level of interest of spending time in the forest, especially for recreational purposes, makes information about the spatial and temporal distribution of activities in forest areas important. This is especially true since introducing the concept of forests with increased social function in 2022. This forest category will include forests that are intensively used for recreational purposes, in the direct neighbourhood of recre− ation resorts and forests in zones A and B in health resorts. The information on the temporal and spatial distribution of social activities, including its intensity, seems to be an essential element for the correct identification of the aforementioned forest category. Taking the above into account, the aim of the study was to use the data generated by mobile phone users to: i) determine the number of people in forest areas in the Forest Promotional Complex ‘Sudety Zachodnie’ in different time perspectives and spatial scales (the entire area of analysis, forest range and grid); ii) determination of activity hotspots (decile 10=highest intensity); iii) defining the characteristics of visitors (gender, age and sports activity profile); iv) place of residence, divided into inhabitants of the counties within Dolnośląskie voivodeship, other voivodeships and foreign tourists. The main results indicate that in 2019, the research area (22.3 thousand hectares) was visited by over 370,000 unique visitors. The average monthly number of visitors to the research area was 30.8 thousand with the volume of visitors varying every month. The highest number of people was observed in July (48.3 thousand) and June (38.2 thousand), while the lowest was observed in May and November, 13.3 and 18.4 thousand, respectively. The study area was most frequently visited by people aged 30−44 (37%), followed by 45−59 (25%) and 20−29 (26%). Among the visitors, 56% were women whereas 44% were men. The analysis of the place of residence of forest visitors over the whole year showed that 46% of tourists lived in Dolnośląskie voivodeship, 40% in other voivodeships and 14% were foreign tourists. The most visited forest areas were located in the Szronowiec, Czerniawa, Kamieńczyk and Orle forest ranges. Data from mobile phones provided information about visits to forests in the Forest Promotional Complex ‘Sudety Zachodnie’. It should be stated that based on the existing literature that the use and specificity of data from mobile phones for visitors’ monitoring in forest areas can be a valuable source of information.
Key words: big data, Forest Promotional Complex, human mobility, mobile phones, monitoring

Abstract: The possibility of using gas sensors in the portable electronic nose to detect the proportion of acorns colonized by Ciboria batschiana was examined. The present research has demonstrated that for such a task a portable electronic nose can be used as fungus−infected acorn tissue emits different volatile organic compounds from healthy tissue. However, the gas sensors used in com− mercially available the PEN3 electronic nose are not selective, therefore the measurements did not provide accurate information about the chemical composition of the odor. It was found that the electronic nose sensors responded to the presence of the fungus to different degrees. There was a difference in the response of the sensors to the presence of different compositions of the measured volatile compounds at different percentages for acorns colonized by C. batschiana. The correlation coefficients between acorn infection level and the response of the sensors were found to be statistically significant. The R² coefficient of the linear regression model reached a value of 0.19 in the cases where the slope coefficients of three predictors were statistically significant.
Key words: English oak, fungi, fungus molecular identification, seed pathogen, volatile organic compounds

Abstract: Knowledge of costs, their structure, and change dynamics are the basis for decision making by forest managers. Furthermore, an understanding of the factors affecting the expenses borne by forest holdings influences forest resource management and is of importance in improving the profitability of silviculture. The objective of this study was to understand the relationships between unit costs of forest management and the attributes of forest districts distinguished on the basis of natural and economic conditions (e.g., forest site type, compatibility between stand species composition and forest site type, silvicultural system, and fragmentation of forest complexes, etc.). This was accomplished using unit costs of forest management in 82 forest districts belonging to the Regional Directorates of State Forests in Białystok, Krosno, and Lublin (eastern Poland) in the years 2005−2009 and 2015−2019. Based on regression analyses, the main forestry activities significantly affecting costs were found to be forest regeneration, tending, protection, investment in infrastructure, as well as timber harvesting and skidding costs. Regeneration costs increased with the degree of management difficulty, while the costs of forest tending were significantly higher in districts managing mountain sites, especially those with fir−beech stands. Outlays on forest protection were significantly greater where the clearcutting system was used and in forest districts with compact forest complexes. Significantly greater bunching and extraction costs were reported by forest districts in mountain areas, where selection silvicultural systems predominated. Cost optimization of forest management can improve the net income of forest holdings, especially in the face of increasing ‘ecologisation’ pressures in forestry and the mounting opportunity costs of nature conservation and biodiversity protection in forests.
Key words: economics of forestry, principal activity costs, costs analysis, natural factors, economic factors

Abstract: Woodpeckers Picinae are recognised as important keystone species in forest ecosystems because many species of animals find shelters or breeding places in cavities woodpeckers excavate. We evaluated the nest tree preference of a European species, the grey−headed woodpecker (GHW), Picus canus Gmel., in the semi−boreal Augustów Forest in northeast Poland, an extensive forest complex covering 114 000 ha, dominated by fresh and mixed fresh coniferous forest. Nest trees made by the GHW were sought within areas identified by the playback of territorial vocalisations and drumming in spring. We found 35 cavities on 31 trees. Twenty−one of these cavities were made in trees of poor health and 14 in dead trees. Only deciduous trees were selected for excavation, specifically aspen Populus tremula L., silver birch Betula pendula Roth., and black alder Alnus glutinosa (L.) Gaertn. Alder was chosen most frequently, but according to Ivlev’s electivity index, the most preferred species was aspen. We found important differences between forest sites used by the grey−headed woodpecker. Most cavities were found in alder forest, with fewer in broadleaf fertile forest, mixed broadleaf forest, and mixed pine forest. Cavity trees were on average 83−years−old (ranging from 45 to 127 years). The average diameter of cavity trees used by the grey−headed woodpecker was 47.4 cm (ranging from 30 to 67 cm), of which the most numerous were trees with diameters between 30 and 40 cm. All cavities were excavated in trunks. Cavity entrances were located at an average height of 8.2 metres (4.5−14 m). The mean height of the first branch on excavated trees was 10.2 metres above ground and was higher than the average height of the cavity entrance. Cavities in birch were placed higher than in other tree species. A linear mixed model explaining cavity height above ground showed important effects for first branch height, which allows for higher placement of the cavities, and tree species, because cavities in aspen and alder were excavated significantly lower than in birch. The GHW preferentially placed cavity entrances on southern and eastern exposures, with entrance aspect related to cavity height above the ground. Our results underline the importance of aspen to GHW and indicate the need to maintain this tree species in managed forests.
Key words: aspen, cavity trees, cavity entrance orientation, habitat preferences, Picus canus