The interest in stumps has increased with recent boost of the bioenergy in Europe. Fuel yield from stumps can be as high as from harvesting residues. The most valuable areas for stump extraction are spruce and pine stands on dry mineral soils. In Finland the utilization of stumps for energy is rapidly moving from the testing phase to forest practice. In 2005 the use of stump wood chips by heating and power plants totalled 0.4 mill. m**3, tripled the consumption of 2004, which corresponds to 14% of the total consumption of forest chips in Finland. Extensive whole-tree harvesting trials in Sweden demonstrate that removal of stumps and slash from clear-felled sites has a strong positive impact on natural forest regeneration. Results from Finland indicate that stump and slash removal can improve productivity and quality of subsequent re-planting of harvested forest sites. The majority of available studies on root rot control demonstrate that subsequent forest regeneration is more successful on sites where the stumps have been removed. The scope of this study was to evaluate quality of forest regeneration after stump extraction in Finland according to the national regulations in Latvia. Number, size, distribution and mortality of seedlings were estimated in 15 compartments. Additionally, moisture and compaction of soils were determined. Results of the study approved that regeneration of forest stands on fertile mineral soils after stump extraction was successful and combination of mounding with scarification during stump extraction provides sufficient growing conditions for new seedlings.

The added value of woodworks is determined by the surface quality because it is the first one seen and evaluated by the client. In the production process it is quite problematic to evaluate woodworks surface quality because of large production capacity, and the processed material can be instrumentally tested with a definite time shift. In production most frequently the surface quality is evaluated visually, which is not quite precise. At the same time during the mechanical processing of wood noise is caused by cutting tools as they gradually wear out. The same reasons influence the increase of noise and the quality of woodwork surface. The essence of the problem is to analyze the registered increase of the noise level at a definite workplace and simultaneously follow the surface quality of the processed material – roughness and wear-out of the cutting instrument. The objective of the paper is to research the method of the noise level data collecting and application in order to evaluate wooden product surface quality during wood processing by milling machines. It would provide an opportunity to update the management processes of massive woodworks, supervise the surface quality of woodworks, reduce costs and increase the added value.

Latvia uses average moisture content and density indexes obtained in Russia and European countries; though, these indexes are different, and there is no information about the most suitable one for conditions in Latvia. Research complex on Latvia’s industrially important tree species - Scots pine (Pinus sylvestris L.) stemwood and bark moisture and density changes, depending on influencing factors, is being conducted at Forestry Faculty of Latvian University of Agriculture. The research results on Scots pine, obtained during the year 2011 in the whole territory of Latvia, are outlined in this article. Wood and bark moisture and density were analyzed in 21 sampling plots, arranged in middle aged and cutting-aged reached forest stands, depending on tree age, cutting time and location place in the tree stem. The average moisture content of pine wood mostly depends on heartwood specific weight and age of the tree. With an increase of tree age, average wood moisture content value decreases from 111% (40-year-old trees) to 77% (145-year-old trees). Scots pine heartwood moisture content changes a little during the year: 30– 34% for 71 to 146-year-old trees; and 34-41% for 37–70-year-old trees. Sapwood moisture content is changes from 113% (in the summer) to 130% (in the winter), without any reference to the age of the tree. The average density of oven dry timber obtained from 71–146-year-old trees in the research is 0.501 g cmE-3, whereas in freshly cut condition – 0.848 g cmE-3.

The Duration of Load (DOL) effect is the combined influence of the mechanical loading history and climatic history on the strength of materials. DOL effect is one of the most important characteristics of wood and wood-based materials. The material degradation or damage induces strength reductions. Creep is one of the most important effects of DOL. Creep is a phenomenon that negatively affects functional compliance, behaviour and strength of timber structures in extended years of exploitation. The creep phenomenon is affected by surrounding temperature, relative humidity, timber moisture content and other factors. The study aimed to establish a correct factor system for accurate prediction of long-term deformations of timber structures that is corresponding to environmental conditions and timber properties in the region of Latvia. The experimental research was made in Jelgava, Latvia, and represents timber beam four-point long-term loading in bending with variable cross section height-span length ratio under uncontrolled climatic conditions. There were 12 timber beams with two different span lengths – 1.32 m and 1.50 m used. The timber beam cross section dimensions: height – 60 mm, width – 30 mm. The timber beams were not dried and the moisture content at the start of the experiment varied from 19% to 33%. The applied load values – 0.40 kN and 0.31 kN. Moisture content fluctuations and negative air temperature accelerated creep development and intensity. Prediction of final long-term deformations should rate not only the type of timber material and service class but the strength class, too.

Within several decades many natural Lithuanian rivers were straightened and adapted for needs of soil drainage. By 1998, 63.4 thousands kilometres of trenches of which approximately 46 thousands kilometres were regulated rivers and streams were excavated. It is calculated that trenches of regulated rivers and streams currently cover 82.6, and natural – only 17.4% of total rivers network. While straightening rivers, their channels were extended, their slopes were changed, and bends were removed. Thus, it ensured a fast removal of excess water from drained areas of ground. However, as in the straightened rivers an equal stream was present, unfavourable conditions arouse for ichthyofauna, as well as for settlement and evolution of the invertebrates. Furthermore, possibilities for selfpurification of water running through the channel were reduced. In order to restore morphological, hydraulic, and especially ecological conditions, close to natural ones, of the straightened rivers, it is necessary to renaturalize them. The analysis of river naturalization and renaturalization ways and means was performed on the basis of the reviewed projects carried out in foreign countries. Four renaturalization methods were identified: self-naturalization, soft naturalization, partial and full renaturalisation. The possibility to use these naturalization methods were evaluated taking into account environmental conditions of Lithuania. The analysis of naturalization projects implementation showed that the best way to rehabilitate Lithuania‘s straightened rivers is to use partial renaturalization method that lets form more favourable ecological environment of rivers. The object of the research was - to evaluate the most suitable naturalization methods for Lithuanian conditions.

The aim of air pollution monitoring is a regular and continuous collection of information on air pollution to prevent hazards influencing ecosystem and its components, including humans. Nowadays, the main technology used for this purpose is electronic sensors. As they are designed for specific measurements, a lot of important factors cannot be evaluated – various pollutants diffusion or cumulative effect, exposure, dose, and bioaccumulation. As an alternative solution – bioindication – pollution level determination from its effect on certain indicator species can be used. So far potential usage of bioindication as current air pollution monitoring network’s equivalent solution has not been studied. Therefore, the aim of the research was to assess a variety of bioindication methods for air pollution determination and their applications in air pollution monitoring. During the research, commonly used bioindication methods based on their popularity in scientific literature in 2012 were selected, as well as they were assessed using theoretical analysis method in order to determine their strong and weak points in air pollution monitoring. Research results demonstrate that current bioindication methods are not suitable for monitoring purposes. Therefore, bioindication can be combined with citizen science approach. To incorporate citizen science approach in bioindication based air pollution monitoring, development of special, for this purpose designed bioindication methodology is needed.

The research was carried out on ASU WRI grounds in Juodkiškes village in Endocalcari Endohypogleyic Cambisol (CMg-n-w-can). Research basis is 3 different field studies. In Variant I an organic cropping system was used with manure and without mineral fertilizers and pesticides, in II - organic-mineral cropping system with manure and mineral fertilizers, using pesticides, in Variant III - mineral cropping system with mineral fertilizers and pesticides. Minimum mineral nitrogen content in soil was in the organic cropping system, and the total minimal field crop capacity - in the mineral cropping system. However, it has the highest energy efficiency of this system (ETK - 13). Minimal N-NO3 - concentration in drainage water was in the mineral cropping system. In the organic-mineral and organic cropping systems concentration of this compound increases by 11 percent (to 21.8 mg l-1). The minimal concentration of ammonia nitrogen was under organic cropping conditions. The organic cropping system showed the highest runoff and maximum leaching of nitrogen compounds by drainage.

The negative impact of agricultural pollution with biogenic materials on surface water bodies is a relevant problem. This problem is addressed by limiting or prohibiting certain activities in the so called buffer areas. The biogenic materials are carried by surface or groundwater runoff. Water infiltration is influenced by the lithological composition of sediments. River basins of sandy lithological structure were selected throughout the territory of Lithuania. An installed system of lysimeters in the boreholes allowed monitoring the change of water quality of sediments over time. The migration patterns of nutrients where identified during the investigation in the spring, summer and autumn seasons.

This work focuses on the demands of scientific and sociopolitical understanding of situation of Latvia where the interaction between different languages and cultures have produced the political map of today. The aim of this work was to determine the differences of election results between rural areas and the city area, as well as to determine the main factors affecting election results in rural areas. Results of the study show that the ethnic factor has a major role in interpretation of the distribution of election results. If the proportion of non-Latvians increased by one percent, then the proportion of voters for Harmony Centre would increase by 0.64 percentage points in Vidzeme and by 0.75 percentage points in Latgale. Conclusions of the study: election results in rural areas differ significantly from the results in towns and cities, but the difference between rural areas and small cities is smaller compared to the cities under state jurisdiction; in rural areas, the national composition of the population has the greatest influence on the election results.

The article analyses organizational internal and external environments, their possible correlations with 4 components of sustainability, and the principal determination models for sustainability of organizations. Based on the general principles of sustainable development organizations, a model for the determination of organizational sustainability has been developed. The use of self-organizing neural networks allows the identification of the external sustainability of each forest enterprise and the endeavour to explore vital, social, anthropogenic and economical efficiency. The determination of the forest enterprise external sustainability is expected to help better manage the external sustainability of forest enterprises and explain the reasons for a respective level of external sustainability.