Leaf morphology was assessed in Pajiesys and Seirijai field trials of oaks. Oaks in these trials are the progenies of oak trees (Quercus genus) that grow in the Trakas forest of Seirijai district of Alytus forest enterprise of Lithuania. The aim of the study was to determine the number of hybrid trees between the progenies of the Trakas forest in Pajiesys and Seirijai field trials. 251 oaks belonging to 40 half-sib families were sampled. Twenty three leaf morphological variables were measured on each of 5 leaves collected from each tree and analysed by principal component analysis (PCA) and discriminant analysis (DA). The study concluded that Q. robur and Q. petraea leaves are most clearly identified by six morphological traits. Discriminant function of two traits for oak species separation was proposed. The study has also revealed a high degree of interspecific hybridization in field trials. Study results were compared with earlier reports about hybridization occurring in mixed oak stands in other parts of Europe.

Pine, spruce and birch stem’s quality is different in regions of Latvia, but the differences are not included in the tables and models of assortment outcome. Therefore, it is not possible to predict accurately the outcome of round wood assortments. The aim of the research was to evaluate the regional differences of final felling sawlog outcome for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and birch (Betula spp.) in Latvia and to set the regions with a different sawlog outcome. Data from 1645 final felling areas was used for pine, 1202 for spruce and 1531 for birch from the years 2010 – 2012. Firstly, the sawlog outcome of 97 territorial units was set by using the data of the final felling areas sawlog outcome of pine, spruce and birch. Secondly, territorial units with a similar sawlog outcome were consolidated in regions. The smallest regional difference of sawlog outcome was found for spruce (9.4%), slightly larger for pine (10.5%) and the largest difference for birch (16.2%). Three regions with the different sawlog outcome were found for Scot pine, six for Norway spruce and seven for birch. Several spruces and birch regions have similar sawlog outcome but those do not have borders. They are between regions with higher or lower sawlog outcome. Sawlog outcome of neighbouring regions differ for at least 4 – 5%.

The study aims to find productivity of biofuel production in pre-commercial thinning, depending on the structure of assortments and to identify factors that influence the cost of mechanized tending of young stands. Five work methods were compared in the study, starting from standard thinning (production of sawn timber, pulpwood and firewood) with no use of accumulating device and finalizing with the biofuel method – no other assortments except biofuel are produced and the most intense use of accumulating device is considered. Accumulating device is not used for production of standard round-wood assortments. The experiments were implemented in February – March, 2013. The material produced in the study was used by ‘Graanul Pellets’ company to evaluate possibilities to use timber extracted in pre-commercial thinning of coniferous stands in production of premium class pellets. The average productivity in different stands is statistically different. The study shows that productivity of harvesting is 3.7 … 5.1 m**3 hE-1, which can be increased by more intensive use of accumulation. No difference found between work methods in forwarding trials, but productivity grows with increase of share of firewood. Average loading time 26 min, unloading 3.6 min, average load 6.0 m**3 . Prime-cost calculation shows that harvesting costs depending on the working method is in the range of 22.4 … 26.5 EUR mE-3. Comparison of potential expenses and incomes demonstrates that economically the most efficient is production of traditional assortments (sawn wood, small size sawn wood, pulp wood and firewood) with an active use of accumulating function.

The study represents results of productivity studies of mechanized ditch cleaning using Ponsse Fox harvester adapted to multi-tree handling H6 head in forest drainage systems managed by Joint stock company “Latvia state forests”. The aim of the study is to evaluate productivity of extraction of biomass from ditches depending on working method and to estimate factors affecting prime-cost of biofuel in mechanized harvesting. The study results demonstrate that the 2nd method (mechanized extraction of roundwood and following motor-manual cleaning of remaining vegetation) is the most efficient solution for mechanized cleaning of ditches. Benefits of the 2nd method are smaller costs of undergrowth removal and bigger output of solid biofuel. Ponsse Fox harvester demonstrated sufficient work quality and productivity in the trials; however, it would be wise to use heavier harvesters or caterpillar excavator based harvesters in ditch cleaning. Using the 2nd method, a harvester can extract about 227 ha of ditches (23,000 m3 ) annually.

Thermal wood modification has been intensively studied in the recent decades because of the possibility to produce wood with improved biodurability and dimensional stability without use of harmful chemicals. Beside altered physical characteristics, wood colour is changed to lighter or darker brown as a result of thermal treatment. Growth of interest in thermal wood treatment has stimulated numerous researches concerned with discoloration of thermally modified wood which is subjected to light exposure. The objective of this study was to evaluate the colour stability of thermally modified hardwood during storage in the dark where wood discolouration is not photoinduced but rather a result of oxidative ageing. Three thermally modified hardwood species – aspen (Populus tremula L.), alder (Alnus incana Moench), birch (Betula pendula Roth.), where investigated. Wood discoloration was monitored by spectrophotometrical measurements of reflectance spectra and chromaticity parameter calculations using CIELAB colour system where L* is the lightness, and a* and b* are the chromatic coordinates. The colour stability of thermally modified wood as well as of untreated wood of the same species was examined by means of assessment of the colour parameter changes (ΔL*, Δa*, Δb*, ΔEab). All wood specimens under study discoloured during the experiment, but the colour change did not exceed two units that are common and accepted for wood products. Untreated and thermally modified wood showed different trends of discoloration during storage in the dark. The final colour changes that were fixed at the end of the experiment were greater for the thermally treated wood.

Cumulative air pollution – synergy between different pollutants and environmental factors is one of the hardest to evaluate factors in the air quality monitoring field. The evaluation of cumulative effects is hindered by a lack of verified analytical frameworks. Currently used methods are relatively simple and use statistical models with small fixed number of pollutants in association with different factors. There is almost no one solution for direct, on-site cumulative effect measurements. The alternative is the use of Cumulative Pollution Index (CPI) method – solution designed for cumulative effect calculation from bioindication and air quality measurement data. However, this method is completely new and has never been used in the air pollution evaluation activities. Therefore, the objective of this study was to evaluate the opportunity to use CPI method as a cumulative pollution evaluation tool in air quality monitoring by doing measurements of cumulative effect in several air quality measurement stations in two cities of Latvia – Liepaja and Riga. Results show that Cumulative Pollution Index method is not only usable in air quality monitoring as a tool for cumulative effect evaluation, but can reveal new facts about air pollution and ways how it affects human and ecosystem health, – such climatic and environmental factors as humidity and temperature are more important than interactions between individual pollutants and can be considered main elements in forming of cumulative pollution impact.

Rural areas in Poland are characterized by great diversity in their functional spatial structure. Throughout history, their distinct features have been shaped by natural, historical and socio-economic factors. The aim of this study was to analyze the changes in the functional spatial structure of North-Eastern Poland. The analysis involved a comparison of data for 1988 and 2012. Research data was supplied mainly by the Central Statistical Office in Poland. The key drivers of change in the investigated region are agriculture, tourism, forestry and environmentally-friendly industrial processes. The results of the economic and social development are constantly changing in rural areas. Based on analysis, the functional structure of rural areas in North-Eastern Poland between 1988 and 2012 shows that they are more diversified. Over the years, rural areas in North-Eastern Poland were identified with agriculture but now they have multifunctional character.

Rural areas in Poland are vastly differentiated in their level of social and economic development. Adverse natural, social, economic and technological processes contribute to the formation of problem areas. Negative phenomena can spread across several municipalities, contributing to the number and severity of problems. Rural municipalities characterized by a low level of social and technical development are not attractive sites for prospective investors or home buyers. Geographical location can also contribute to the formation of problem areas. The Region of Warmia and Mazury borders the Kaliningrad Region, and it is one of the least developed areas in Poland. Rural areas in Warmia and Mazury are characterized by significant disparities in the level of social and economic development. The aim of this paper was to identify problem rural areas in the Region of Warmia and Mazury based on indicators of social, demographic, economic and infrastructure development. Problem areas in the Region of Warmia and Mazury were identified using Hellwig’s taxonomic measure of development. The results of our analysis indicate that in rural areas in the Region of Warmia and Mazury, the most severe problems are observed in typically agricultural municipalities which have a peripheral location and where state-owned farms had acted as the main employer.

The most efficient way to dewater sewage sludge is the thermal drying, which simultaneously with the granulation allows obtaining the product in the form of granules, being a non-putrescible fertilizer that is also easy for transportation, storage and bringing into soil. When large volumes of sewage sludge are formed, which are unfit for use in agriculture, application of other utilization methods, such as burning, would be purposeful. The aim is to determine the optimum drying modes of sewage sludge with application of pneumatic pulse method at treatment facilities in the pilot project. To do this, it is necessary to develop a proposal for the design of operating model. The design and making of working model is necessary to determine the optimal conditions for sewage sludge drying at sewage disposal works. The drying process is provided to be realized in a closed-loop cycle (without emission into atmosphere). Due to inner recirculation of dry air, the installation heat consumption is reduced. Calculations have shown that there is economic expediency of using the pneumatic pulse method in sewage sludge thermal drying technology and possibility of using sewage sludge as an alternative fuel. Optimization of sewage sludge thermal drying process with the use of pneumatic pulse method will considerably extend the perspectives for utilization and further use of sewage sludge.

The research was conducted during the period of 2007-2011 in the fields fertilized by manure of pig breeding complex. According to the fertilization value of manure, the following total nitrogen levels reached the fields each year: 2007 – 169, 2008 – 167, 2009 - 168, 2010 - 168, 2011 – 168 kg haE-1. Ptotal reached the fertilized fields accordingly: 2007 – 9.4, 2008 – 18.9, 2009 – 12.0, 2010 – 10.8, 2011 – 13.5 kg haE-1. The aim of the research was to explore the impact of manure fertilized fields of a pig breeding complex on the water quality of streams. Streams, flowing through fields fertilized with manure, are usually polluted with nitrogen. The increase in Ntotal concentrations in streams’ water below fertilized fields was affected by precipitation (r = -0.31), fertilization rate (r = 0.41) as well as mineral nitrogen reserves in the soil (r = 0.20). Phosphorus concentrations in streams’ water were low and corresponded to a very good streams’ water ecological condition, except in times, when the water inflowing into the fertilized fields was already contaminated with this element. It was determined that an extremely high impact on streams’ water quality below fertilized fields comes from Ptotal concentration in streams’ water above fertilized fields (r = 0.91) as well as from the drainage water inflowing from fertilized fields into the streams (r = 0.71). Neither Ntotal, nor Ptotal pollution was observed in drainage water, because the highest concentrations during the research period were lower than the maximum allowable concentrations by 1.1 and 6.5 times respectively.