The purpose of the study was to compare forest and postagrogenic soils by parameters such as carbon content in organic matter and total nitrogen to predict the fertility state of lands that are at the stage of restoration of woody vegetation. Areas with similar soil formation conditions were selected on the postagrogenic and forested lands having mature forest stands related with such types of forest: Myrtillosum forest, Oxalidosum and Herbosa-Composita forest, and also areas under the soil complexes of postagrogenic fallow lands. A number of physico-chemical indicators for the soil were assessed according to the methods generally accepted in soil science: the particle size distribution, the bulk density and the thickness of the pedogenic horizons were determined. An analysis of the carbon stocks in organic matter (Corg) and nitrogen (Ntotal) in the genetic horizons of the soils of myrtillosum, Oxalidosum and Herbosa-Composita forest types shows an increase in the content of organic matter and total nitrogen from Myrtillosum to Herbosa-Composita forest type. A comparative analysis of the physical and agrochemical state of postagrogenic and forest soils showed that, despite the previous anthropogenic impact, the agroland horizon retains a high content of organic matter and total nitrogen. The properties of postagrogenic soils in the studied areas are not deteriorated, and the transformation towards the natural forest soils of the region is not observed, despite the long period of fallowing.

A demand for wood resources is increasing. In addition to drainage and appropriate regeneration and thinning, the forest soil fertilization may increase the future harvest rates. Therefore, the improved growth of forest stands raises in priority among the research topics related to forestry. The objective of the study is to evaluate the impact of nitrogen fertilizer on soil water and throughfall water chemical composition to elaborate recommendations for the forest fertilization. The trials were conducted in a birch stand and in three coniferous stands. Nitrogen containing mineral fertilizer (ammonium nitrate) was distributed in the study sites, while the control plots were left without any treatment. The water samples were collected a season before and a season after the soil treatment. The pH level, total nitrogen, potassium and phosphate were determined in throughfall and soil water samples. The chemical properties of throughfall water differed depending on the forest stand type. The concentration of nitrogen was higher in throughfall water samples collected from the birch stand. The mean concentration of total nitrogen was 1.6 ± 0.3 mg LE−1 in the throughfall water samples from the birch stand compared to 1.03 ± 0.11 mg LE−1 in the throughfall water samples from the coniferous stands. Although the forest soil was enriched with the nitrogen fertilizer, there was a significant increase in concentrations of potassium and phosphate in soil water samples from certain stands. It can be explained with changes in pH level that occurred after the forest soil treatment with ammonium nitrate. There was also a significant increase in total nitrogen concentrations in soil water samples at the depth of 30 cm from the treated plots of the coniferous stands – 15 ± 6 mg LE−1, compared to 1.5 ± 0.03 mg LE−1 in the samples from the control plots. However, the concentrations decreased within two months and remained at a steady rate – slightly above the control level.

Forests offer a wide variety of ecosystem services, including cultural or recreational services. In that sense, state-owned forest lands hold the biggest responsibility to acknowledge and provide these services, where it is economically and ecologically viable. Suitability analysis has been extensively used to provide information on species conservation measures, and it is possible to apply similar techniques for potential supply of recreational services. A simple weighted overlay analysis was conducted to locate forest land areas most suitable for potential recreational activities. Several criteria were selected for the analysis, including forest stand parameters such as forest stand age, forest stand type and species, topographical diversity and remoteness. Basis for the weighting of the selected criteria were obtained from the social surveys, previous research work done in Latvia and the Baltics, and European scale scientific data on recreation preferences. The analysis showed that 20% of the total model area analysed provide substantially high recreation potential. Furthermore, these preliminary data can be used for surveying and facilitating community involvement processes. Local tourism and nature leisure activities can be promoted by exploring possibilities of alternative forestry planning options, utilizing such multifunctional assessments of recreational supply.

The establishment, maintenance and renovation of forest drainage systems are carried out to ensure the development of high quality forest stands and to secure access to forest resources, but it also poses a risk of erosion and increased discharge of suspended solids and nutrients associated with it. The aim of the study was to analyse the efficiency of standard-sized sedimentation ponds built by JSC ‘Latvia’s State Forests’ for sediment and nutrient retention during and after drainage network maintenance. To assess the efficiency of standard-sized sedimentation ponds six study sites were established and various chemical and physical parameters were measured for three years to evaluate water quality and to estimate runoff of plant nutrients and suspended solids. Sampling was carried out before and during drainage network maintenance and during two years following it. Despite the fact that some effect in reducing suspended solid export from catchments was observed, the results revealed insufficient efficiency of the sedimentation ponds in retaining plant nutrients and eroded matter during and after the drainage network maintenance. Retention of Ntot, N-NO3 sup(-) , P-PO4 sup(3-), N-NH4 sup(+) and DOC was ambiguous. It was concluded that other water protection structures should be considered or different parameters of sedimentation ponds should be used to improve the water quality exiting the drainage systems and entering waterbodies.

Freshwater lakes and rivers are habitats of variety of organisms and their populations giving great importance for freshwater ecosystems and providing water resources, food and recreational possibilities for humans. In spite of their fundamental importance to humans, freshwater lakes have been affected by anthropogenic disturbances, which have led to serious negative effects on the structure, functions and quality of these ecosystems. Lake ecosystems are dependent on inflow of water and supply of matter and energy from their catchment area. In studied lakes significant anthropogenic impact in loads of nutrients in their sediments and water was detected. This highlights the well-known problem of freshwaters in the World and in Europe – eutrophication, which can lead to increased productivity of water ecosystems – increased algae blooms, spreading of macrophytes and decreasing of oxygen content in water. Studied lake ecosystems show presence of human impact, not only by physiochemical parameters, but also by changes in biomass production, cyanobacterial algal blooms and overgrowing with macrophytes was observed. In order to improve water quality, appropriate management measures should be applied. We have analysed advantages and disadvantages of such measures as sediment removal, constructing of wetlands, cutting reeds and forming ecotones.

Resorts in the Republic of Lithuania are residential areas with natural healing factors (mineral water, healing mud, health-friendly climates, recreational areas and water bodies) and a special infrastructure enabling them to use these factors. Currently, there are 4 resorts in the country: Birštonas, Druskininkai, Neringa and Palanga. The purpose of this article is to carry out an analysis of the anthropogenic landscape of the resorts of the Republic of Lithuania in 2007-2018. During the preparation of the article, the following scientific methods were used: literature analysis, determination and evaluation of the current situation, grouping method, comparison method, analytical and statistical analysis methods, logical analysis, graphical method. The analysis showed that the anthropogenic landscape of the three resorts increased: in Druskininkai – by 362.65 ha or 18.17%, in Neringa – by 113.43 ha or 52.78%, in Palanga – by 190.74 or 15.09%. The anthropogenic landscape of Birštonas has decreased by 41.11 ha or 5.03%. Over the past decades, with the intensification of anthropogenesis and its accompanying urbanization, the importance of the natural environment has become more and more understood, and landscape research, which is associated with the assessment of naturalness and its problems, is becoming more and more relevant.

This study is important to contribute morphometry researches and give an example of how to accomplish studies about lakes. The aim of the study is to use the latest technology to determine the morphometric parameters and their variability compared to the previous research results. Research focuses not only on local water body morphometry and bathymetry, and their influencing factors, but also deals with methodological issues regarding measurements of morphometric characteristics and data interpretation as well as state of the art visualization of results. On many occasions, there is a lack of research on morphometry of water bodies or they have taken place in the last century, which has led to the use of obsolete research methods in modern morphometry studies that do not produce the results of a high level of detail. The aim of the study is to use the latest technology to determine the morphometric parameters and their variability compared to the previous research results. The study consists of analysis of the literature on morphometry, methodology used in bathymetry studies, history of research, research methods used in the previous studies. The research object is Lake Kisezers including its morphometry, bathymetry, and influencing factors. The results of the study show that morphometric parameters of Kisezers differ from the results of previous studies. The results of the study confirm that Lake Kisezers is exposed to various influencing factors, mainly anthropogenic. The main factor influencing morphometry and hydrological regime in Kisezers is the water level fluctuations influenced by Riga Hydroelectric Power Plant.

Global scale environmental problems and economic issues are the main aspects what point out exigency to do research in the construction of renewable building materials. Renewable building materials are those materials that can be regenerated quickly enough and in theory, their production could be carbon-neutral. In order to evaluate the thermal efficiency of renewable materials in the framework systems of building envelope structures, test samples were made with the filling of renewable materials. The aim of the work is to find out the thermal conductivity coefficient of these natural composites and to compare them. Different size test samples were created for determination of thermal conductivity coefficient: 1.type as reference value: (width x height x depth) 290 x 290 x 30 mm; 2.type as experimental construction value (imitation of real wall construction): (width x height x depth) 980 x 980 x (165; 250; 345) mm. In this research as renewable insulating materials were used: maple leaves, legume (Galega orientalis), the composition of hemp shives (Bialobrzeskie) and sapropel with lime. A renewable insulating materials (also known as eco-thermal insulating) as alternative building materials discussed in this research work meets the requirements of the normative documents of the Republic of Latvia on sustainable construction principles. The analysis of results indicates significant difference among investigated materials – 0.040 W mE−1KE−1 lowest obtained value of thermal conductivity coefficient.

This paper investigates the effect of fuel bias between the primary and secondary injectors of a staged fuel injection system on the performance of a high output single cylinder spark-ignited internal combustion engine. It is known that staged fuel injection systems are widely used in motorsports applications where high engine speeds are coupled with high power output, therefore, the aim of this study is to evaluate the effect of a secondary fuel injector installed on a Honda CRF450R single cylinder four-stroke gasoline engine. The said engine was equipped with a programmable Performance Electronics PE3-SP0 control unit and a secondary fuel injector identical to that of OE. Power measurements were carried out on a Dynojet-200ix chassis dynamometer in four different modes with altered fuel proportion between injectors, with each measurement being repeated three times. Ambient conditions were monitored with Performance Electronics Pe3Monitor software and the fuel map was adjusted to produce a stable air-fuel ratio. The results were averaged and compared numerically and by coefficient of correlation. It was observed that the data as obtained from the chassis dynamometer software SportDyno 4 contains a lot of noise, both mechanical and electrical in nature, and the changes in power output are highly dependent on engine and equipment temperature. The best results were obtained by using both injectors with fuel proportion biased to the front of the system.

Perfect packaging exists in nature – examples include banana peel (Musa sapientum fixa cortices L.) and eggshell (Ovi testa L.), together with the many smart materials and systems that control plant and biological functions. Smart packaging is a type of packaging, which in addition to performing the four basic functions of packaging such as protection, communication, convenience and containment, also offers several additional functionalities depending on the type of product. Changes in consumer preference for safe food have led to innovation in packaging technology. The market for smart packaging systems has a promising future by integrating them into packaging materials. For food retailers, smart packaging is a huge development in helping to reduce food waste. The aim of this study was to assess the awareness and attitudes of food manufacturers and retailers to the introduction of smart packaging systems into the Latvian market. A survey reflected knowledge about active and intelligent packaging and its possible introduction into the Latvian market. Ten manufacturers and ten food retailers from different regions in Latvia answered 16 questions, including how well they were informed about smart packaging and how much consumers would be willing to pay for it. In addition, the food manufacturer and food retailer confidence in the impact of smart packaging on a product storage quality was analysed. The results revealed that manufacturers and retailers in Latvia have a poor understanding of the new opportunities which could be offered by using technologies of smart packaging.