Listeria monocytogenes is a pathogen that causes infectious diseases in animals and foodborne infection in humans. The aim of this retrospective study was to analyse L. monocytogenes caused abortions in cattle in Latvia in 2013, and to describe the potential reasons of these abortions. In total, 186 cattle abortion cases were investigated. The pathological material from aborted foetuses included samples of brain, heart, liver, spleen, kidneys and lung, liquid of stomach and liquid from thoracic and abdominal cavities. These samples were tested with bacteriological methods according to ISO 11290-1:2007. L. monocytogenes was found in 44 (23.7%) cases of cattle abortions. Positive cases were more distributed in the central and the south-eastern parts of Latvia, because in this territory winters tend to be wetter and colder than in other parts of Latvia. Seasonality was observed of L. monocytogenes caused abortions and the majority of cases occurred during spring and autumn, when the cattle were fed with silage. All abortion cases were observed in the second and the third trimester of the gestation. L. monocytogenes caused abortions occurred in cattle of different ages, but significantly (p is less than 0.05) more often – in 3 years old cattle.

Nowadays excessively used corticosteroids in veterinary medicine induce steroid hepatopathy in dogs (Canis lupus familiaris). The objective of this study was to determine the possibility of the hepatoprotectants to decrease the corticosteroid-induced alteration in such dogs’ blood serum enzymes as alaninaminotransferase (ALAT), gammaglutamyltranferase (GGT), alkaline phosphatase (AP) and corticosteroid-induced thermostable alkaline phosphatase (cAP). The study took place in private veterinary clinics in Riga, Latvia, during 2013, with the permission of dogs’ owners. Twenty eight animals, which received corticosteroids due to present diagnosis, were divided into two groups. In the first group long-lasting corticosteroid methylprednisolone acetate injection was used once, while in the second group the hepatoprotectants were used after the injection of corticosteroids. It was discovered that after 14 and after 30 days of hepatoprotectants use, blood enzymes were significantly lower (p is less than 0.05) than in dogs that did not receive hepatoprotectants. In both groups the enzyme values did not reach the reference limits. The study is set to investigate further if and when the values reach the reference limits.

An important factor in the development of forest ecosystem is the ability to regenerate. Natural intensity of self thinning of a forest depends on the tree species and environmental conditions. Due to abiotic and biotic factors in a continuous forest tract, there appears a clearing, which, depending on the size, forms new growth conditions. Over time, the resulting new space is occupied by herbaceous and woody vegetation. Most often regeneration of a new forest depends on the size of the plot. The study was conducted in 2013 during the growing season in a typical broadleaf forest stand. During the study woody vegetation and projection coverage of herbaceous vegetation was registered in large clearings. Light conditions in the plots and under tree canopies, as well as soil parameters were ascertained. Based on the collected data, the view of the structure of woody vegetation, projection coverage of herbaceous vegetation, light conditions, temperature, soil moisture content and pH changes were obtained. In order to clarify the influence of microclimatic conditions on natural forest regeneration, the data on light and soil characteristics were analyzed. The aim of the study - was to determine the changes of woody and herbaceous vegetation in spruce stand clearings and to assess the impact of microclimate. During the study it was found out that in large plots dominated species demanding higher amount of light, while herbaceous vegetation was attributed to the third, fourth groups of aggressiveness. Naturally regenerated seedlings condition was mostly influenced by light conditions and soil moisture content.

The influence of forest distribution in the landscape on precipitation in middle latitudes is poorly researched. Moreover, results of such studies are controversial. Nevertheless, most researchers agree with findings, that influence of landscape roughness formed by forests on the amount of precipitation is significant. This study aimed to extend knowledge of the interface between forest distribution and the amount of precipitation during particular periods. Database of the amount of precipitation from 31 Lithuanian meteorological stations during the period of 2002-2010 was used in this study. Findings defined statistically significant correlations in the amount of precipitation increase due to shorter Euclidean distance to the nearest forest edge in the particular landscape (r = -0.421 – -0.359), p is less than 0.05), also shorter distance of the meteorological stations to the nearest forests (r = -0.380, p is less than 0.05) and higher density of the forests, treated as a perimeter per area ratio (PAR) (r = 0.359 – 0.551, p is less than 0.05).

Latvia is one of the forest-richest countries in Europe. Very often in young forest stands of spruce admixture of coniferous or deciduous trees are taking place. During the growth trees suffer from influence of different risk factors. Damages in mixed stands depend on chosen mode and intensity of economic activities. Forest management cannot be imagined without creating the infrastructure (roads, ditches, etc.). However, the development of infrastructure may cause an effect of fragmentation and lead to changes in the forest structure. The aim of the research is to analyze influence of forest spatial features on the sanitary state of mixed stands of spruce. In 2011 and 2012 mixed stands of spruce younger than 40 years were investigated in all regions of Latvia. Nineteen stands were measured and surveyed and 80 sample plots were arranged. With the help of Geographical Information System (GIS) data base of the State Forest Service of Latvia the forms of forest plots (regular or irregular), as well as location of neighbouring infrastructural objects and location of mixed stands in forests were stated. In unnaturally created regular form plots damages of risk factors usually tend to be larger than in those, which have been created naturally. With the credibility of 95%, linear connection between occurrence of damages caused by browsing and intensity is relevant (r=0.937 is greater than r0.05=0.575), as well as occurrence and intensity of damages caused by Lophophacidium hyperboreum Lagerb. (r=0.999 is greater than r0.05=0.575).

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.

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.

Invention of light weight cellular wood material (CWM) with a trade mark of Dendrolight is one of the most important innovations in wood industry of the last decade. Currently CWM has been used as core material for sandwichpanels. These three layer panels are used in furniture industry and have wide non-structural applications. The aim of the research was to define the thermal properties of CWM and evaluate various wall envelopes where solid wood cellular material is used. There were 4 specimens of cellular wood material manufactured with nominal dimensions thickness 120 mm, length and with 600 mm to determine thermal conductivity and thermal transmittance according to standard EN 12667:2002. The specimens were manufactured of four layer 112 mm thick Scots pine (Pinus sylvestris L.) CWM double faced with 4 mm thick high-density fiberboard (HDF). Adhesive used in the bonding process was polivinilacetate Cascol 3353. Each direction (parallel, perpendicular) was represented by two specimens. Common procedure to evaluate the energy efficiency of building envelope is to calculate thermal transmittance in static conditions. The influence of the cellular material orientation to its thermal properties was investigated. Coefficient of thermal conductivity was determined for both material directions of CWM (l0 =0.0977 W∙m-1∙K-1 l90=0.148 W∙m-1∙K-1), combining the test method of EN 12667:2002 and calculation method of standard EN 6946:2008. To calculate thermal transmittance of various wall envelopes calculation software in JavaScript environment was created. Various compositions of external walls were assessed, thermal transmittance of these structures were calculated according to standard EN 6946:2008.

When the measurements of power consumed by cutting mechanism electromotor are made, the mechanical cutting power cannot be obtained, because they are different physical processes. However, determination of electricity power is relatively simpler. Therefore, both powers are determined in the study, in order to evaluate coherence between them. Computer numerical control machine was used for climb-sawing of aspen (Populus tremula L.) wood with a circular saw. Mechanical cutting power was calculated from measurements of cutting force, but the electric ones – from measurements of current and voltage. As a result, changes of both powers and of specific cutting work, on what the analytical calculation of cutting power is based, were obtained depending on length of the cutting trajectory. It is found out, that mechanical cutting power is greater than electric power, and it is useful to use for the analytical calculation, based on determination of the specific cutting work, wear coefficient of the cutter that depends not only on the duration of work of cutter, but also on feed speed and the length of the cutting trajectory.