The article presents hydraulic conductivity modelling results of the some regulated Southeast Lithuanian streams overgrown with woody vegetation. Possibilities to plan naturalization of the regulated streams are also presented in the article. The research of woody vegetation was carried out in the Neris river basin within the period of 2006 to 2007. Having evaluated the influence of hydraulic roughness (Manning coefficient of roughness) on hydraulic conductivity of the rivers Nemėža and Ž-2 streams it was established that the density of woody vegetation in the investigated section varied from 0.01 to 0.68 units m-2 in Nemėza stream and from 0.17 to 3.12 units mE-2 in Ž-2 stream. At the existing density of woody vegetation the hydraulic roughness coefficient n established by hydraulic calculations reached in 0.025–0.045 in Nemėža stream and 0.033–0.053 in Ž-2 stream. Under present hydraulic roughness coefficient assessed by natural investigations in all investigated streams sections, when spring flood discharge probability is 10%, water overflow indicator is positive; the water depth in the bed (zv) of the natural reaches was lower than the depth of a regulated stream (hG). The reserve of hydraulic conductivity in the investigated Nemėža stream section is lost when roughness coefficient reaches the limit of 0.080, in Ž-2 stream 0.060. When roughness coefficient reaches 0.170, water overflowing indicator is negative in all investigated sections of the streams.

Cultivars of northern highbush blueberries (Vaccinium corymbosum L.) are the most suitable for areas with long, cold winter, because they require the greatest number of winter chilling hours. The blueberries are excellent sources of phytochemicals that are believed to have a significant biological activity. The experiment was done at the Institute of Agrobiotechnology, Latvia University of Agriculture, Jelgava, in the year 2009. The aim of the experiment was to evaluate phenological development of 9 highbush blueberry cultivars, their yield, fruit weight and biochemical composition: total anthocyanins, total phenols, ascorbic acid, titratable acids, and soluble solids. The obtained data showed correlation between duration of flowering and fruit ripening; between harvest and end of vegetation period of the highbush blueberry. The phenological development was dependent not only on cultivars, but also on the effective air temperature (above + 5 deg C). The research results allow assessing the phenology development of blueberry cultivars and predicting the fruit ripening time in conditions of Latvia. The most productive cultivars were 'Patriot' and 'Northland' The biggest single berry weight presented the cultivars 'Chippewa' and 'Bluejay'. The cultivar 'Jersey' had the highest content of titrable acid, anthocyanins, and ascorbic acid. The highest phenol content was detected in highbush blueberry cultivars 'Spartan' and 'Bluecrop'.

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.

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.

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.

Within several decades many natural Lithuanian rivers were straightened and adapted for needs of soil drainage. By 1998, 63.4 thousands kilometres of trenches of which approximately 46 thousands kilometres were regulated rivers and streams were excavated. It is calculated that trenches of regulated rivers and streams currently cover 82.6, and natural – only 17.4% of total rivers network. While straightening rivers, their channels were extended, their slopes were changed, and bends were removed. Thus, it ensured a fast removal of excess water from drained areas of ground. However, as in the straightened rivers an equal stream was present, unfavourable conditions arouse for ichthyofauna, as well as for settlement and evolution of the invertebrates. Furthermore, possibilities for selfpurification of water running through the channel were reduced. In order to restore morphological, hydraulic, and especially ecological conditions, close to natural ones, of the straightened rivers, it is necessary to renaturalize them. The analysis of river naturalization and renaturalization ways and means was performed on the basis of the reviewed projects carried out in foreign countries. Four renaturalization methods were identified: self-naturalization, soft naturalization, partial and full renaturalisation. The possibility to use these naturalization methods were evaluated taking into account environmental conditions of Lithuania. The analysis of naturalization projects implementation showed that the best way to rehabilitate Lithuania‘s straightened rivers is to use partial renaturalization method that lets form more favourable ecological environment of rivers. The object of the research was - to evaluate the most suitable naturalization methods for Lithuanian conditions.

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.

Zemgale geobotanical region historically was dominated by large broad-leaved forests, but last centuries the high anthropogenic pressure on these territories has reduced the area of these forests. In fragmented landscape small patches of natural broad-leaf forests are protected to preserve the forest structural features, which also function as habitats for rare and protected species. The aim of this study was to compare the natural broad-leaf forest habitats and structural elements and vegetation in woodland key habitats in production forests and protected areas (nature park ''Tērvete'' and nature reserve ''Ukru gārša'') in Zemgale. In total, 12 sample plots were established (the size of sample plot 0.1 ha) in Aegopodiosa forest type. In all sample plots forest structural features were measured and vegetation survey using Braun-Blanquet method was made. In this study, we found that average amount of dead wood varies between 78.7 m**3 haE-1 in woodland key habitats in production forests and 133.0 m**3 haE-1 special protected areas. Considerable amount of broad-leaf natural forests represented by nemoral species (50 – 58% of species richness), which corresponds to these forest type communities in the region.

The capercaillie Tetrao urogallus L. is a typical bird species inhabiting structurally diverse coniferous forests. To increase the habitat quality of capercaillie leks, experimentally the habitat restoration in degraded ecosystems has been practiced. The main habitat restoration events are related to the reversion of hydrological regime and understorey layer management. The aim of this study was to find out how the management of lek sites – mowing of Ledum palustre L. and ground vegetation – promotes the regeneration of the vegetation typical of the capercaillie leks. Three sample plot blocks of 10x30 m have been established, which have been divided into 3 variants of 10x10 m. The first is a control plot, in the second plot an entire ground vegetation mowing was performed, while in the third plot – the ground vegetation mowing in a 3 m wide strip was carried out. The vegetation was determined using the BraunBlanquet recording form before the management – in August 2015, and after the management – in August 2017. The condition of the habitat of capercaillie is inadequate before management, since Ledum palustre prevails in the ground vegetation. Both types of ground vegetation management have had a significant impact on the projective cover of Ledum palustre. After mowing the entire area, it has decreased by half, but after mowing in a strip, it has decreased by 30%. The ground vegetation mowing in a strip enhances positively the regeneration of dwarf shrubs and herbaceous vegetation.