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The aim of the research is to analyse the landscape structure changes from the end of the Soviet times in 1974– 1986 until 2005 when market economy existed in Lithuania. The changes of landscape structure were observed in 100 sample areas (squares) each of them having 2.5 km2 area and distributed in different landscape types. The changes in sample areas (squares) with determination of land cover structure transformations were observed using topographic photos and ortophoto images at a scale 1:10 000. More distinct manifestation of landscape re-naturalisation through land abandonment and conversion to forests, swamps and shrubs, also through transformation of arable land to meadows and pastures was the main direction of land cover changes. The opposite but lower scale conversion of forests, shrubs and other land use types to agrarian fields was also noticed. Acceleration of the conversion of landscape structure towards technogenisation through quick expansion of construction, recreational use and development of infrastructure was another important landscape structure conversion going on in the opposite direction of technogenisation. It manifested mainly as the change of agrarian fields, suburban gardens to built-up territories and as increase of percentage of other land use types related to them (ponds, streets and roads).

55 plant species included into the Lithuanian red book were chosen and analyzed. The analysis revealed that the plants of a medium height (20 species) dominate. The flowers of 17 plant species are violet, and 48 species have green leaves. After analyzing bio ecological properties of rare plants it is possible to say heliouphilous plants dominate (37 species), majority of plants flower from the beginning of June until the end of August (50 species). 25 rare plants under research are allocated to category 2 (V) and are considered to be quickly extinct, endangered species, the population number of which and the number of individual plants decrease rapidly. The main reasons of the plant disappearance are the overgrowing of habitats by trees and bushes (58,18 %), irrigation and drainage (36,36 %) as well as intensive farming (29,09 %). The research identified that the main protective measures of rare plants are the support of the traditional farming, the limitation of hay harvesting and grazing, the maintenance of water hydro chemical , hydrological and hydrographic regime, etc.

The investigation of hemp crop weediness was carried out at the Upytė Experimental Station of the Lithuanian Research Centre for Agriculture and Forestry in 2014. Bi-factorial trial was carried out: Factor A – variety (A1 – USO 31; A2 – Bialobrzeskie); Factor B – sowing rate (B1 – 45 kg ha^-1; B2 – 70 kg ha^-1). Data showed that seed rate had a significant influence on crop density at full hemp emergence as well as at harvesting time. Rainy vegetation period was favourable not only for hemp growing, but for weeds as well. Crop density (resulted by seed rate) had a significant influence on crop weediness – significantly more weeds (in average 166 plants m^-2) were found in the plots with seed rate of 45 kg ha^-1, consequently at lower crop density, and under 140 weed plants m^-2 were found in the plots with seed rate of 70 kg ha^-1, consequently at higher crop density. Hemp crop weediness at harvesting time was much lower than that at the beginning of vegetation; reduction of weediness over the vegetation period was close to 87-90 percent.

scientifically the following categories are excluded: biodiversity, geoheritage, geodiversity, geo tops, nature objects and others. They are important from the scientific, aesthetic, tourism, cultural points of view. The aim of environment sciences has to be to analyse the categories exhaustively and to determine the conditions of protection.

To avoid antagonism in system nature-economy-society the concept of state territory management has to be based on the principles of sustainable and balanced development. The strategy of economy development should follow not only the criteria of economical effectiveness, but also the indexes of ecological stability of the territory.The extent of ecological polarization (measure of landscape stability) is conditioned by the combination of (1) landscape geochemical sensitivity and (2) technogeochemical pressure defined in respective territorial units. With respect to self-cleaning features of landscapes 7 levels of geosystem sensitivity were distinguished and mapped in Lithuania territory. The largest part of the territory is occupied by averagely and more than averagely sensitive geosystems, the least area is taken by relatively insensitive and extremely sensitive geosystems. The technogeochemical pressure was evaluated through the detailed analysis of landscape technomorphological structure. Using the GIS data bases, in the technotopes distinguished the technogeochemical pressure was evaluated according to the area of industrial and built-up territories, agricultural lands, road net density (adjusted by traffic intensity), and dosmestic pollution (assessed according to the population density). Each of the agents was given different weitcoefficients in regard to its pollution emissions. The layer superposition of the geosystem sensitivity and technogeochemical pressure gave the emergence of cartoscheme revealing the distribution of areas with different ecological polarization, divided into 5 tension levels. In order to distinguish the priority territories of land management and optimization the polarization area net and the natural frame of Lithuania were superposed.Knowledge of the ecological polarization areas allows the rendering of recommendations to economy units for their economical activity organization that should be developed considering the means of landscape ecological stability maintenance like increase of forest percentage, formation of geochemical barriers, proper distribution of land use.