Yasso07 soil carbon model was used to estimate soil carbon balance in dry forest site types (6 site types in total) in Latvia and the results were compared with data from Biosoil2012 soil surveys. Litter input, chemical quality and climatic data are required to run the model. Three different scenarios were used for climate data input – steady climate, climate change + 0.025 °C annually and climate change + 0.05 °C annually. Forest mineral soil is a carbon sink for the whole modelled period - the years of 1990 – 2030. Under steady climate, the average carbon removal is 0.6 t CO2 haE-1 yrE-1, under climate change (+ 0.025 °C) scenario 0.4 t CO2 haE-1 yrE-1, but under climate change (+ 0.05 °C) scenario 0.3 t CO2 haE-1 yrE-1. CO2 removal at the beginning of the period (1990) was 0.35 – 0.38 t CO2 haE-1 yrE-1. Carbon stock modelled with Yasso07 is lower than estimated in Biosoil2012 soil surveys. Differences between modelled and Biosoil2012 results vary from 2 t C haE-1 in the poorest and 41 t CO2 haE-1 in the third poorest site type. Carbon stock modelled with Yasso07 increases from the poorest to the most fertile site type while Biosoil2012 shows an increase from the poorest to the third poorest, and a decrease from the third poorest to the most fertile site type. Underestimation and different trends between Yasso07 and measured carbon stock may be explained by inappropriate equations and models used to estimate non-woody biomass. It is necessary to improve accuracy of input data for non-woody biomass by elaborating national equations and models in order to include Yasso07 in the national GHG inventory.

Urban forests provide ecological and social functions and significantly improve esthetical value of these ecosystems. These forests also function as recreational areas for urban residents. The aim of this study was to assess the influence of understory cutting of different intensity on vegetation and coincidence with Myrtillosa forest type in Mežaparks, Riga. In total nine study sites were established: three sites adjacent to roads where regular undergrowth management is practiced, three adjacent sites to edges of the pathways, where undergrowth management is practiced only occasionally and three adjacent sites to roads where there is no management activity at all. Combined 54 sample plots were created (each sized 10 × 10 m, area 100 m2 ), where vegetation survey was done using Braun-Blanquet method. This study showed that with an increase in the intensity of undergrowth management, in general, the species richness and their coverage increases, or more specifically, the number of herbaceous and moss species increases, but the occurrence of shrub species decreases. In all study sites we observed the development of synantrophic species, especifically, the development of fructification which was indicated by the following species: Sambucus nigra L., Sambucus racemosa L., Amelanchier spicata Lam. If management intensity decreases, the proportion of competitor species decreases, but the proportion of CSR strategy type species stabilizes.

The objective of the research was to characterize the qualitative and quantitative changes in ground and tree vegetation within 10 years since the beginning of observations at Level II forest monitoring plot in Valgunde. Tree height, diameter, stem volume, radial increment, crown condition and cone yield were determined, as well as crown projective cover of each plant species was estimated. To study bioindication, the average Ellenberg’s and Düll’s indicator values for the monitoring plot were estimated. Species composition in the Level II monitoring plot in Valgunde is typical for Myrtillosa forest type – there is a distinct moss layer, in which Hylocomium splendens and Pleurozium schreberi predominate, and Vaccinium myrtillus is the most common in the herb layer. Shrub layer mainly consists of spruce seedlings, and the tree layer – of Scots pine. Changes in vegetation over 10 years are insignificant. It can be explained with no forest management activities occurring within the observation plot, such as logging or fertilization, and it may take a longer time to observe significant changes. Tree stand indicators correspond to the average in Latvia in Myrtillosa type forests, but the tree volume is higher in Valgunde monitoring plot.

The biological control agent Rotstop, composed of spores of Phlebiopsis gigantea, is used for treatment of conifer stumps to reduce the spread of Heterobasidion root rot in commercial forests. Two experiments were conducted to compare the antagonistic ability of the Rotstop isolate and nine Latvian isolates of P. gigantea against root rot fungus Heterobasidion, in wood of Scots pine and Norway spruce. Billets of conifer trees were first sprayed with a spore suspension of P. gigantea and then with Heterobasidion at different concentrations. The presence of fungi in billets was evaluated by morphological characteristics of mycelium. The Latvian isolates of P. gigantea showed similar or even higher values of efficacy against Heterobasidion (average efficacy 84% in spruce and 89% in pine) than the commercially manufactured Finnish preparation Rotstop (61% in spruce and 90% in pine). Latvian isolates of P. gigantea have a potential to be used for preparation of biological control agents in the future.

European beech (Fagus sylvatica L.) timber value is high in southern Europe due to a great demand from Asia. Since the timber market is global, over a long time we can expect gradual increase in demand also in other countries, including Latvia, where climatic conditions becomes increasingly more suitable for this species due to ongoing climatic changes. In order to develop recommendation for the use of beech in our country, the aim of the study was to assess the potential financial gain from Fagus sylvatica stands in Latvia. Assortment structure, defined by topdiameter and length, as well as their prices was set based on the literature survey. Results showed higher income from older (115 years) than form younger (58 years) stands: 9108 EUR haE-1, and 7939 EUR haE-1, respectively. However, the opposite was true for the net present value (r = 3%): 1423 EUR haE-1 and 304 EUR haE-1, respectively.

Surface water runoff, formed in the company areas due to changing wastewater discharge and pollution fluctuations can be treated in retention ponds. Pollutants, released into the ponds, mineralize during complex natural biochemical processes in the aquatic environment. The paper presents the long-term observation data (2004 – 2016 m.) on the purification of surface wastewater, formed in the company’s production territory, in retention ponds. The aim of this work is to identify surface wastewater purification efficiency in retention ponds. Wastewater samples were taken before and after biological treatment. The samples were investigated in the Chemical Analysis Laboratory of the Water Research Institute of Lithuania University of Agriculture. Biochemical oxygen demand (BOD7 ) was determined with titrometric method, suspended solids (SS) – with gravimetric method, having filtered the substance through a mid-thickness filter. Concentrations of oil pollutants were determined with the help of a spectrophotometric device of infrared rays IKAN-1 in the Analytical Department of Agrochemical Study Center of Lithuanian Agricultural Institute. Although the suspended solids, BOD7, and oil hydrocarbon concentrations, released into the natural environment, were below the MAC when they are collected from the company’s production areas, they are often contaminated; therefore, it is necessary to treat them. The purification efficiency of researched materials was satisfactory and reached 61, 64 and 91%.

The plants emit different types of volatile organic compounds (Bio VOC’s) and can improve air quality: they effectively remove organic pollutions and reduce the number of microorganisms in the air by releasing phytoncides. The lack of negative ions in the air can cause deterioration of the health of humans breathing it. At the same time, an air saturated with negative ions can improve the state of health and provide a comfortable environment. In this article, the influence of the plants (Cupressus macrocarpa) on the number of ions is proved, based on a series of experiments performed with applying high-voltage pulses (air ionizer). This work is devoted to the elaboration of the mathematical relationship between the air ions concentration and the factors influencing it. For this purpose an experimental stand was made, consisting of two equal compartments: one contained the plants while another one was used as a control without plants. It was concluded that the plants, in general, are able to stabilize the ion concentration and to reduce its fluctuations. The plants help to increase the concentration of negative ions and to decrease the concentration of positive ones.

The article presents the analysis of the current situation of the damaged land in Klaipeda County. The study found that the number of affected areas in the county – 266. Because the damaged areas consist of mineral quarries and territories occupied by dumps, the article contains the description and condition of these areas. It was found that mostly sand deposits (60) predominate in Klaipeda County, of which only 8 are used. The smallest number of the deposits – the salt deposits (2). The mainly used deposits in the county are sand and gravel deposits – 29, unused – sand deposits (52). The Klaipeda municipal waste management region comprises 7 municipalities, 39 old landfills and dumps were shut down. At present, 1 regional non-hazardous waste landfill has been arranged. In Klaipeda County, in 2015, damaged land occupied 2,391.06 hectares and amounted to 0.46 percent of the county’s area. During the period between the years 2005 and 2015 the damaged land area in Klaipeda County increased by 130.25 hectares. The analysis of the damaged land by type of ownership showed that the damaged land areas in private land increased by 75.54 hectares or 58.52 percent. In the state land, the damaged land area decreased by 442.35 hectares or 20.04 percent.

The aim of the paper is to explore the possibilities of detection and reduction of land degradation in Smarde municipality rural territory (56°57′18″ N; 23°20′17″ E). To carry out land degradation prevention measures, initially the territories of degraded land should be determined. This paper highlights the field inspection method. For territory inspection a model was used that gave the opportunity to identify degradation types with their characteristic features and possibilities to reduce the land degradation. The territory of Smarde municipality rural territory was inspected in nature and degraded territories identified. The costs of land degradation elimination depend on the type of land degradation. In territories where the land degradation reduction or elimination has been done, its control has to continue in order to stop the development of land degradation.