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.

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.

Woody plants at urban greeneries in Lithuania are injured by rust fungi of 13 genera, 28 species: Coleosporium pulsatillae, C. tussilaginis, Cronartium flaccidum, C. ribicola, Cumminsiella mirabilissima, Gymnosporangium clavariiforme, G. confusum, G. cornutum, G. sabinae, G. tremelloides, Hyalopsora aspidiotus, M. allii-fragilis, M. allii-populina, M. caprearum, M. epitea, M. laricis-populina, M. populnea, Melampsora ribesii-viminalis, M. salicis-albae, Melampsorella caryophyllacearum, Melampsoridium betulinum, M. carpini, Ochropsora ariae, Phragmidium tuberculatum, Pucciniastrum areolatum, P. symphyti, Uromyces caraganicola, U. pisi-sativi. During 2009 – 2017 Gymnosporangium sabine had the strongest damages (from 0.21 ± 0.00 to 2.43 ± 0.33 grades) on Pyrus pyreaster, the weakest damages had done G. cornutum on Sorbus intermedia and S. x thuringiaca ‘Fastigiata’ – 0 – 1 ± 0.58 grades.

Sewage sludge is a rest product deriving from the wastewater treatment plants. It is rich in nutrients and essential elements. Therefore sludge on-land utilisation can create an added value by recovering energy from biomass produced on marginal lands. However, widespread on-land recycling of sewage sludge might be limited due to high heavy metal content. Health organisations show an increasing concern about the risks posed to the environment and human health as many countries worldwide already are facing the heavy metal contamination problem. In the scientific literature it can be found, that high total heavy metal content is not directly related to an intensive metal uptake by plants. In this study samples were collected from three woody plant species (black locust, silver birch and aspen) growing directly on the sewage sludge in a storage site near Kaunas, Lithuania. Heavy metal content was detected separately in the leaves, stems and roots. It was determined that nearly all analysed heavy metals (lead, chromium, nickel, copper and zinc) were accumulated within normal range despite high total concentrations in the growing media, and only cadmium was accumulated at elevated concentration. Based on bioaccumulation factor, aspen could be considered as a Cd-accumulator and used for phytoremediation purposes.

The paper presents the study material and analysis of the distribution of woody vegetation of regulated streams in southeast Lithuania. The studies were carried out in 110 randomly selected slope strips of regulated streams in the Neris River basin in the Baltic Highland within the period of 2005 to 2006. During the studies 32 species of woody vegetation were found, from which 14 species of trees and 18 species of bushes. In regulated streams different species of willows are most common. However their distribution on channel slopes is different. For most species of woody vegetation the conditions are most favourable in the lower and middle part of slopes. Here their density is highest (0.34 +- 0.89 and 0.73 +- 0.139 units mE-2 respectively), the frequency is 0.56 and 0.64 respectively. As it was determined, the frequency of woody vegetation on slope strips of regulated streams is na = 0:61. On the slope the lower overgrowth limit of woody vegetation is ra = 1:58 +- 0:16 m, the upper limit is rv = 4:13 +- 0:22 m. In southeast Lithuania, in discharge network of drainage systems there are more possibilities for planning of ecological means, when trees and bushes are allowed to grow on slopes.