One of the biodiesel production problems is occurrence of a significant quantity (about 10%) of the by-product – glycerol. This problem is offered to solve by adaptation of bacteria Zymomonas mobilis, which is notable for ethanol production facilities. To be able to process glycerine into ethanol using Z.mobilis bacteria, the bacteria must be modified. At the same time, computer modelling analysis is required to assess specific modification affectivity in interconnection with other processes in bacteria. Computer model results of simulated experiment to understand and predict that the cells and biological processes are essential to reduce the number of experiments. This in turn reduces the necessary financial resources and time, bio-medical biotechnology, pharmaceutical and environmental problems. The model describes conversion of glycerol into bioethanol in Z.mobilis bacterial cell. First phase of model creation is creation of a structure model based on biochemical reactions using computer software CellDesigner. On the second phase of model creation, kinetic parameters which are available in literature were identified. Using the databases KEGG, SABIO-RK, BRENDA, reactants, kinetic parameters and reaction equation types were defined. Dynamic model of Z. mobilis biochemical network was created using computer software Copasi. The dynamic model describes conversion of glycerol into bioethanol in Z.mobilis bacterial cell. In this time simulation data of the computer model of natural organisms are not to confirm laboratory experimental data. Simulation data of the computer model are not correct to prevent this problem is required parameter estimation in computer software COPASI.

The most important part in forest inventory based on remote sensing data is individual tree identification, because only when the tree is identified, we can try to determine its characteristic features. The objective of research was to explore remote sensing methods to determine individual tree position using LiDAR and digital aerial photography in Latvian forest conditions. The study site was a forest in the middle of Latvia – in Jelgava district (56º39’ N, 23º47’ E). Aerial photography camera (ADS 40) and laser scanner (ALS 50 II) were used to capture the data. LiDAR resolution was 9p m2 (500 m altitude). The image data is RGB, NIR and PAN spectrum with 20 cm pixel resolution. Image processing was made using Fourier transform, frequency filtering, and reverse Fourier transform. LiDAR data processing methods was based on canopy height model, Gaussian mask, and local maxima. Field measurements were tree coordinates, species, height, diameter at breast height, crown width and length. Using combined LiDAR and optical imagery data allows detecting at least 63% of all trees and about 85% of the dominant trees.

Heterobasidion spp. is an important pathogen in the Northern Hemisphere, causing root and butt rot mainly in conifers. Norway spruce (Picea abies (L.) Karst.) is one of the most common tree species infected by Heterobasidion spp. In Latvia, 22.9% of Norway spruce stumps are infected. Heterobasidion spp. decreases timber quality, but what impact it has on Norway spruce growing in understory of dominant stand is not known. The aim of the study was to evaluate incidence of Heterobasidion spp. on understory Norway spruce in Myrtillosa forest type and impact on radial growth of trees. In autumn of the year 2011 in a sample plot located in forests of Kalsnava district a total number of 258 trees were examined for presence of Heterobasidion spp. Results showed that 54% of examined trees were rotted. In 30% of trees Heterobasidion spp. was detected. It is concluded that Heterobasidion spp. does not impact radial growth on understory Norway spruce trees.

The aim of the study was to investigate the properties of hyperspectral reflectance data of Scots pine (Pinus Sylvestris L.) and Norway spruce (Picea Abies L.). The hyperspectral reflectance data was obtained under laboratory conditions from the last season’s needles of healthy 20 year-old trees from the same site. Hyperspectral data was acquired using Themis Vision Systems LLC VNIR 400H portable scanning hyperspectral imaging camera in 400-1000 nm range. Methods of analysis of variance, discriminant analysis and principal component analysis were applied for the hyperspectral data analysis. Differences between Scots pine and Norway spruce reflection data were examined. The most informative spectral range for Norway spruce – Scots pine spectral separation was determined at 666.5 nm – 668.4 nm, most informative waveband - 667.1 nm. Reflectance variations among individual trees of the same species as well as differences in spectral response between needles from northern – southern crown exposition were tested. A significant variation in spectral response of needles of Norway spruce was detected across the whole measured spectral range (955 wavebands) for each sample tree. However, significant variation of spectral response of needles of Scots pine was detected only in 356 out of 955 wavebands for each sample tree. Depending on the crown exposition to the North or South, the reflectance of Scots pine needles differed significantly in 900 spectral bands. No significant differences were detected in 833 wavebands for Norway spruce.

Distribution and status of common juniper (Juniperus communis L.) in Lithuanian Pine stands are investigated in the study. The research was conducted in pure pine stands on sites with normal humidity and poor fertility in South – South Eastern parts of Lithuania. 40 stands were selected for data collection. Temporary rectangular sample plots with area of 10 square m were selected. According to method of underbrush evaluation, diameter root neck level, height and state index was measured for 3 juniper individuals located near the centre of sample plots. The number of sample plots depended on the area of each stand, but it was not lower than 10 in each stand. Average diameter of junipers was 3.03 cm, average height – 2.03 m. It was determined that average density of juniper individuals is 5055 individuals per hectare, and separately in vacciniosum and vaccinio – myrtilosum forest types - 4844 and 5282 individuals per hectare respectively. Average state index of juniper individuals in 6 grade scale was 2.96, which is near to grade 3 (slightly damaged). Results of the study show that distribution, status and dendrometric characteristics of junipers are different in adjacent regions of pine provenance.

The article focuses on vegetation diversity in the black alder Alnus glutinosa (L.) Gaertn. woodland key habitats in Zemgale, Latvia. Together nine sample plots were established on these habitat types, where next stand South – South West (S-SW) side at the age 1-10; 20-30 and 40-50 years. The vegetation survey has been made in vegetation period of 2010 and 2011. Braun – Blanque method has been used to estimate the projective coverage (%) of tree layer (E3), shrub layer (E2), herb layer (E1) and moss layer (E0) in order to assess the edge effect impact on vegetation diversity according to different ages classes in a next stands of sample plots. The analysis of edge effect verifies that there is a significant influence from the edge in 1st and 3rd zones of sample plots, which lies at S-SW side at the ages 1-10 and 20-30. In sample plots several indicator species of black alder woodland key habitats have been found: Vaccinium myrtillus L., Lycopus europaeus L., Iris pseudacorus L., Comarum palustre L., Plagiomnium ellipticum (Brid.)T.kop. Ordination confirmed that composition of species are relatively close, which demonstrate that species are able to live in similar type growing conditions. Protective species Circaea lutetiana L. and Plagiothecium undulatum (Hedw.) B., S. et G were found on the study sites. Also, adventive species Impatiens parviflora DC was found. Comparing the analysis by zones and sample plots and different age classes, the impact on edge effect has been distinguished in black alder woodland key habitats.

Tree roots take up a high proportion of forest biomass, and nowadays we use different methods to estimate the root biomass. Methods vary greatly due to the different studies and different excavation methods used. In the summer 2010, a study of the below-ground biomass of young Scots pine Pinus sylvestris L. stands was carried out in central Latvia. In this paper, different below-ground biomass fractions data of 10 sample trees from the abandoned agricultural land plantations were approximated by allometric functions depending on tree stem diameter at breast height 1.3 m (DBH). The main objective was to determine the average below-ground biomass and approximated below-ground biomass fractions by allometric functions depending on tree DBH of young stands of Scots pine on abandoned agricultural land. Our regressions offer good overall approximations of the data. DBH – stump, coarse root and small root and total biomass regressions were highly significant (p is less than 0.001). The most substantial part of total below-ground biomass was from stumps (45%). The smallest shares of the biomass were coarse roots 38% and small roots 16%. The largest portion (52%) of the total fine-root biomass of 12- and 14-year-old Scots pine stands was located at a depth of 0–10 cm, decreasing in deeper mineral soil layers. Total dry (DM) below-ground biomass including fine-root biomass was 19.0 ±5.2 t DM ha-E1.

With the increase in demand for renewable energy resources, new studies are carried out about under - utilized resources, namely, stumps. To begin to use stumps in industrial application, it is necessary to find out stump extraction influence on the environment, biodiversity, forest regeneration and other important factors. In Zemgale forestry, Misas and Klīves forest districts managed by Joint stock company “Latvian State Forests” (LSF) study on stump extraction in woodlands where clear-cuttings done in 2006 was carried out in the block No. 177, compartments No. 1 and 5, as well as the block No. 176, compartments No. 3 and 9. In these territories two research objects were made where in November-December 2007 stump extraction as well as soil preparation were performed. Main tasks of the project were to evaluate the results of forest natural seeding and coppice ingrowths in natural regeneration areas and evaluate the use of different methods for artificial reforestation with spruce and pine containerized seedlings. It was observed that more seedlings were cut off in the areas where soil scarification with stump extractor was performed if compared to areas prepared with a disc trencher.

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.

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.