Experience saved in the construction industry shows that the timber portal frames with semi-rigid connections at knee joint exhibit permanently increase displacements at the knee and apex point. Normally, timber portal frame with semi-rigid knee joint connection is made with mechanical fasteners located in double circles and cannot be designed without relevant rotation at connection during structures’ exploitation time. The only way to increase connection rigidity is to rise distance from fasteners location at connection, but at the same time, the tension and shear stress become significant at the external section of members. The previous experience is obtained by a model testing showing that deformations at semi-rigid connections are non-linear. These were tests under short-term load and did not disclose creep effects, which can be significant. This study is aimed at the examination of increasing deformations with time under constant static load (creep effects) in semi-rigid dowelled connection. Experimental test models were made and set under long-term load in controlled environmental conditions (heated laboratory room). Results show a significant creep influence to decrease connection stiffness. Corresponding numerical test of orthotropic 3d model by Dlubal RFEM software tools was performed analysing the value of expected deformations. Results of the numerical test showed that friction between timber elements and extra nuts on bolts can increase connection stiffness. Research results in this stage show that the creep can affect connection stiffness more than expected. Also, experimental test results showed lower deformation values comparing with the ones obtained by the numerical test.

Small rivers are important in terms of water quantity and quality as these rivers collect and deliver water to medium and large rivers downstream. Due to low water flow and high connectivity to adjacent land, small rivers are highly vulnerable to changes caused by natural and anthropogenic factors. This paper aims to assess the chemical and ecological quality of two small rivers including the Slocene and Age as related to dominant land use cover in the contributing area of these water bodies. The effects of land-use patterns and concentrations of chemical substances TN, NO3**- -N, NH4**+ -N, TP and PO4**2- -P in river waters will be determined. The highest concentration of total nitrogen (TN) as measured in the Slocene River was 21 mg LE−1 in spring, while the lowest concentration of TN was 0.86 mg LE−1 in autumn. The highest concentration of total phosphorus (TP) in the Slocene River was 0.14 mg LE−1 in late summer, the lowest was 0.03 mg LE−1 in late autumn. Similarly, in the Age River, the highest concentration of TN was 4.90 mg LE−1 in spring, while TN the lowest concentration of TN was 0.51 mg LE−1 in late autumn. The highest concentration of TP in the Age River was 0.3 mg LE−1 in summer, while the lowest 0.05 mg LE−1 in autumn.

Wet soils play an important role in hydrological, biological and chemical processes, and knowledge on their spatial distribution is essential in forestry, agriculture and similar fields. Digital elevation models (DEM) and various hydrological indexes are used to perform water runoff and accumulation processes. The prerequisite for the calculation of the hydrological indexes is the most accurate representation of the Earth’s surface in the DEM, which must be corrected as necessary to remove surface artefacts that create a dam effect. In addition, different resolutions for DEM give different results, so it is necessary to evaluate what resolution data is needed for a particular study. The aim of this study is to evaluate the feasibility of using existing ditch vector data for DEM correction and the resulting implications for soil moisture prediction. Applied methodology uses a network of available ditch vectors and creates gaps in the overlapping parts of the DEM. The data were processed using open source GIS software QGIS, GRASS GIS and Whitebox GAT. Ditch vector data were obtained from JSC Latvian State Forests and the Latvian Geospatial Information Agency. The results show that by applying the bottomless ditch approach in forest lands on moraine deposits, depending on the accuracy of the ditch vector data, the values of the prediction of the soil wetness both increase and decrease. On the other hand, in forest lands on graciolimnic sediments it is visible that predicted soil wetness values increase in the close proximity of ditches. For forest lands on glaciofluvial and eolitic sediments there were no visible changes because of lack of ditches.

One of the modern education problems being investigated is a phenomenon of student procrastination and minimisation of its influence on achievement of career goals. A transformative pedagogical experiment was carried out involving 1st year engineering students of Latvia University of Life Sciences and Technologies during the 2018/2019 academic year. The aim of the transformative pedagogical experiment was to promote the reduction of student procrastination levels and achievement of their goals by practical experimental approbation of a career education program. During the experiment, self-evaluation of student procrastination was performed before and after the implementation of the career education program. The methodology included 20 indicators of procrastination self-evaluation. The program included three topic-based parts: 1) understanding and setting student career goals; 2) defining procrastination levels and factors; 3) the influence of procrastination minimisation on career goals’ achievement. The study results allowed to conclude that due to the career education program elaborated and implemented in practice, substantial changes in student procrastination self-evaluation took place during the transformative pedagogical experiment. There was a significant difference in student procrastination levels before and after the transformative pedagogical experiment. The study results demonstrated that the elaborated and experimentally implemented career education program is valid and can be further used for minimisation of student procrastination, it can contribute to career goals’ achievement and for the reduction of early discontinuation of studies and dropping out of university as there is a correlation between procrastination and dropout phenomena.

Dead wood is a significant component in forested ecosystems. In Fennoscandia and Baltic countries, set-aside forest areas, also called woodland key habitats (WKHs), have been created for nature conservation purposes in the production forest landscape. We performed a comparative study on dead wood substrate availability in different WKH types in Latvia. We measured standing trunks and downed logs to estimate biological quantities and qualities for coarse woody debris substrate. In this study, we found out that dead wood availability ranges, on average, from 38.2 to 149.5 m**3 haE−1. This study showed that moderate quantity and quality of dead wood has been found in different types, but the fine quality coarse woody debris was scarcely presented. In general, WKHs provide moderate and high level of qualities and quantities of structural features in the production forest landscape.

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.

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.

The aim of the paper is to present the spatial diversity of water resources in the Kuyavian-Pomeranian Voivodship during the drought in 2015. The region’s area is characterized by the lowest average annual precipitation in Poland, the lowest water resources and high water demand associated with intensive plant production. Hydrological research was carried out in September 2015 in 145 measurement points on various rivers. Despite the low precipitation recorded in August 2015 at the majority of meteorological stations, the volume of the specific discharge from the Kuyavian-Pomeranian region was characterized by high variability. The largest specific discharges were recorded for rivers located in the northern part of the region whose sources are located in the Pomeranian Lake District, i.e. Brda and Wda (over 2 dm3 sE−1 kmE−2) and the Masurian Lake District (Drwęca over 1 dm3 sE−1 km E−2). The smallest specific discharges (less than 0.5 dm3 sE−1 kmE−2) were recorded in the catchments located in the Kuyavian region (Tążyna, Zgłowiączka and Noteć) in the southern part of the Kuyavian-Pomeranian Voivodship and from the Osa River catchment. These areas are intensively used for agricultural purposes. The use of surface water resources as a potential source of irrigation water for crops can only be taken into account in connection with groundwater resources.

Wet areas in agricultural lands are usually not fully or properly managed due to problematic accessibility by heavy machinery and are associated with lower crop yields. There are neither studies regarding spatial distribution of wet agricultural areas in Latvia nor large scale soil maps. Being aware of these wet areas, it would be possible to plan actions for effective management of these areas, starting with a scale of landscape. A geographic information system model could serve as an assistant for decision-making, such as, a direct support for the management of amelioration systems, change of land use and management patterns or granting support payments. Remote sensing data like Sentinel-2 satellite images and LiDAR (Light detecting and ranging) technology can be used to identify local wet areas. The focus of this article is to evaluate different remote sensing indices and methods that can be used to identify wet areas in agricultural lands using open access data and software. From 52 indices, which were analysed with soil moisture field measurements in 33 sample plots, only two of them showed statistical significance in linear regression model (p is less than 0.05): normalized height model in resolution of 25 meters (r2 =0.45) and visible blue spectral band in April (r2 =0.39). Results from this study help to focus on different aspects of remote sensing data usage and methodology for future improvements in order to fully implement LiDAR and Sentinel-2 data for identification of wet areas in agricultural lands.