Birch sap is colourless or slightly opalescent and is traditionally drunk in spring. Currently, birch sap is becoming more important in the market sector as well as to pharmacy companies due to its biochemical composition and use in a wide variety of products. To extract good quality sap using birch resources in a sustainable way, there is a need to investigate the influence of the dendrometric parameters of birch trees and soil properties on the quantity and chemical composition of birch sap. This study is performed in five silver birch (Betula pendula Roth) forest stands growing in Histosol, Luvisol and Arenosol with different moisture and nutrient contents. The results indicated that the most productive silver birch trees for sap harvesting were taller than 28 m, had a diameter at breast height over 40 cm and a crown base height greater than 19 m. Additionally, the highest quantity of birch sap was harvested from trees growing in well-aerated mineral soils (Arenosol and Luvisol) with normal moisture content. However, the sweetest birch sap was harvested from trees growing in nutrient-rich organic (undrained peatland Histosol) and temporarily flooded mineral (Luvisol) soils.
Many countries of the world, including Lithuania, are making an effort to reduce surface water pollution. State monitoring data show that almost 80% of the lakes in Lithuania have an increased amount of sludge. One of the reasons for this increase in sludge is an excessive amount of biogenic material in the water. It is known that even after the source of pollution is removed, the condition of the lake water does not improve; rather, the condition of the lake water worsens due to the secondary pollution of sludge in the water. A study was conducted to determine the impact of secondary sludge pollution on water. For this study, 5 sludge samples were taken from different lakes in Lithuania. Fresh water was poured on the sludge samples, the concentrations of Nt, NO2-N, NO3-N, NH4-N, PO4-P, Pt, the pH and the changes in the electric conductivity (C) were measured in the water within 28 h. Research has shown that the thickness of the sludge layer influences the total amounts of nitrogen, phosphorus, and organic matter present in the sludge. As the thickness of the sludge layer increases in a lake, the total concentrations of nitrogen, total phosphorus and organic matter increase. Studies have also shown that the concentrations of all biogenic substances in water increase, with the exception of total phosphorus. This finding shows that organic phosphorus is "locked" in sludge, and no secondary pollution occurs from this source. Moreover, the electrical conductivity values of the water influence the release of biogenic substances from sludge in the water.
In Lithuania, free-ranging European bison live sedentarily in the fragmented landscape of the central part of the country. The aim of this study was to analyze the distribution and habitat selection of European bison in a semi-isolated territory. Free-ranging European bison living sedentarily have formed six groups in the mosaic landscape of central Lithuania. A herd of 34 individuals of European bison entered into a new semi-isolated territory in 2016. During the snow-free season, we tracked the movements of the herd by fitting a global positioning system (GPS) collar to the leading cow. To evaluate the home range and habitat selection, we used ArcGIS software, Jacobs’ index, and chi-square testing to verify significant differences between proportions. The home range of European bison was largest in spring, decreased in summer, and increased again in autumn; this was associated with feeding and the food supply in agricultural lands. European bison spent more time in the forest, especially during the daytime, due to disturbance, but in summer time and at night, the bison did not avoid agricultural land. In the forests, European bison preferred clear-cut, small-leaved deciduous (aspen, grey alder) forests of middle and mature age, but they avoided broad-leaved deciduous (ash), coniferous, and young forests. The increased number of European bison caused damage to agricultural crops and increased conflict with farmers.
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