Recently we have been noticing words as 'sustainable development', 'environment protection', 'environmentally friendly' etc more and more often. We understand meaning of those concepts, but there are no unambiguous definitions of these words in literature. Each of these notions includes particular characterizing elements which understanding and characterizing of which make possible to detect correctness of application or context. Sustainability like entrepreneurship is a process which takes place within definite environment around it. Mutual interaction of the processes produces consequences which have to satisfy all the interested parties. Therefore, it is necessary to integrate several science branches to solve this problem- i. e. economics and ecology. Nowadays, environment issues become part of each person, institution, policy and law. Environmental questions are integrated in different fields of economics and entrepreneurship, as well. It is hard to define environmentally friendly entrepreneurship. But there is a flexible definition that could be used in different economical spheres with great variability of economical circumstances, and it is- characterised circumstances would not be secured for a long time, yet. It is complicated to define the concept since this is a value involving process. Values which are sources for idea of sustainable development are based on need to form society satisfying human interests and unthreatening future generations, necessity to secure economical growth including moral, social and ecological aspects.

Nowadays, linkage of landscape ecology with landscape aesthetics becomes very topical, especially when people move from rural areas to big towns and cities. Landscape ecological planning becomes more important in terms of sustainable environment. Landscape assessment and investigation needs a multidisciplinary approach. The aim of the study was to evaluate landscape ecological aesthetics in urban area. The selected city for study was Jelgava – city with a special characteristic landscape of Zemgale plains and wide green spaces in the city centre. Jelgava is one of the examples of complex urban system with ecological environment. This research presents landscape evaluation of Jelgava using ecological aesthetics assessment method. Territory of Jelgava was divided in groups of research areas: green spaces, residential areas and other territories. Qualitative and quantitative methods were used in the research. The methods applied in this research describe the present situation of the city. Landscape inventory, biotope structure analysis and evaluation of landscape ecological aesthetical qualities give a general overview of the problems and opportunities of the examined city. Research study was managed in autumn and winter 2011. The results show the need for sorting the cityscape and use of ecological principles in further urban planning. Green areas of Jelgava are ecological and aesthetical valuable but multi-storey residential areas have low quality of landscape ecological aesthetics.

The research was accomplished within the framework of the doctoral thesis, with the aim to clarify the role of Latvian Manor Park in the settlement landscape ecology. Significance of the Latvian Historical Park in the settlement landscape ecological processes in Kuldiga district was discussed and analyzed. To achieve set objective of the research, there was developed the landscape ecology assessment methodology of the settlements in the influence of the historical parks based on generalized scientific cognitions and researches in the landscape ecology, and scientific researches of the population loads and historical park value. The developed method was applied by surveying the selected historical parks in the settlement, and by assessing biodiversity factors, urbanization load, and landscape ecological networking compatibility degree. As a result, the selected settlements of historical parks were marked in the district of Kuldiga in the landscape ecological map, highlighting the importance of both national and European level. The results indicate significance of the historical parks in the settlement landscape ecology and that the role of historical parks in the settlement landscape ecology is essential, which ensures the natural basic resources air, water and soil quality. In the settlements, the historical parks existence is high value and quality environmental guarantee, which would have been managed according to the proposed principles of landscape ecology science.

Willow species are nowadays extensively studied. Species are being investigated to evaluate their use and role in various sectors of national economy. The use of willows in short rotation coppice (SRC) for biomass and energy production has a priority in the European Union policy. There are many countries that have grants and financial aid system for so-called ‘green energy’ production. Willow species also have other economically and ecologically important features: resistance to contaminants, strong root system, high tannin contents, decorative, etc. Willow SRC systems are used for phytoremediation and in wastewater purification, in combination with biomass production. There are several countries of Eastern Europe researching adequacy of the willow SRC for the farmland contaminated by radionuclides segregated from the Chernobyl nuclear power plant disaster. Willows are used for quarry restoration, water sludge treatment, erosion control etc, but the most important field at the moment is the biomass production.

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.

Catch crops contribute to soil and environmental quality, which has determined a growing interest in their use as a nature-based solution. Though, the introduction of catch crops increases the complexity of farm management and is related with additional costs. In Latvia, the area under catch crops accounts for less than 5% of the arable land, while 30% is bare over the winter. In order to identify the possibilities for promoting of catch crops in Latvia, the objective of the study is to explore the support practices for growing of catch crops in the Baltic Sea region countries. The paper seeks to explore the main benefits associated with the growing of catch crops, followed by the study and synthesis of the main support measures. For the study, numerous information sources have been explored and appropriate research methods applied. Catch crops reduce nutrient leaching from the soil, transfer nutrients to the next crop, improve soil quality, reduce soil erosion, and mitigate climate change; these benefits can translate also at farm level, mainly as reduced N inputs. Growing of catch crops is being increasingly supported in the Baltic Sea countries – as a greening measure and by different agri-environment and climate measures of the RDPs 2014−2020. Growing of economic focus area catch crops (supported in quite a similar approach in these countries) and introduction of agri-environment scheme for catch crops (supported in directly and/or indirectly targeted way) can contribute to the solving of environmental problems and decrease the share of bare land left over the winter in Latvia.

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.

The article provides the research data on the variation of organic matter in the Jaugila Stream, which flows through drained fields fertilized with organic fertilizers. The aim of the research was to determine the effect of manure application in drainage basin to the changes of organic matter concentration in the Jaugila Stream. Water samples for chemical analysis were taken once a month from the drainage water and the river. The samples from the river were taken upstream and downstream manure fertilized fields and the drainage water – from the outlets of the drainage system, which drains the fertilized area. Water analysis was performed by the Analytical Laboratory of Chemical Analysis of the ASU Water Research Institute. BOD7 was determined by titrimetric method. The research has shown that a greater impact on the increase of BOD7 concentrations in the Jaugila Stream was due to the stream water, saturated with the organic matter, flowing from the upstream areas, rather than the drainage water flowing into this stream from manure fertilized area. The assessment of BOD7 concentrations according to the water quality requirements for surface waters determined that in most cases the water of the Jaugila Stream, both in above and below fertilized areas, was in a very good or good ecological status. The impact of manure fertilized areas on the organic matter concentration in the stream was determined to be minimal, as the statistical analysis of the data has shown that the difference between BOD7 concentrations above and below fertilized areas is negligible.

After the private ownership of land was restored and a part of land reclamation structures was given to land owners, the intensity of land use has changed. In the areas of Lithuania, which are less favoured for agriculture, the land is not intensely used. Further financing of land reclamation of such areas from the state budget grants is economically inefficient as the return of relatively high investments is very low. With the changing of land reclamation infrastructure it is necessary to prepare measures which would facilitate rational, regional agricultural specialization corresponding to natural conditions. The routine procedure of financing the land reclamation has to be changed as well. The paper analyses the changes in usage of drained land areas and financing of the land reclamation sector in Lithuania during the last decade (1997-2007). The purpose of this research is to establish the criteria of the economical efficiency of drainage systems and to propose methods how to change the financing of state-owned land reclamation infrastructure. On the grounds of the carried out situation analysis, a methodology of distributing state grants for land reclamation to municipality budgets are presented. To have an efficient use of the state budget funds, the operation and maintenance of shared land reclamation systems have to be carried out according to the maintenance plans approved by municipalities, which would provide for arrangements and compensations due to conflict of interests arising when land plots are used in different ways. Possible ecological measures that could be applied when carrying out repair and reconstruction of drainage systems are discussed.

Due to intensive agricultural activities being developed in Middle Lithuania, the water quality of rivers in this region significantly decreases. Rivers, flowing through the town territory, should provide aesthetic delight to the residents, however, because of pollution, especially at the end of summer; they are usually covered in duckweed and algae layer. The paper presents the change of the main water pollution indicators (BOD7, Ntotal, NH4 -N, NO3 -N, Ptotal, PO4 -P and O2) in Dotnuvele and Smilga streams during 2013 – 2015. The aim of research is to determine the change of the main surface water pollution factors in Dotnuvele and Smilga streams, depending on the meteorological conditions. Data analysis showed that dissolved oxygen, nitrate and total nitrogen concentrations are affected by air temperature: the lower of the air temperature, and the more of these elements were found in the water of the streams, (r = -0.61), (r = -0.83) and (r = -0.64) respectively. An increasing precipitation was also increasing the amount of O2 and NO3 -N in stream’s water, (r = 0.44), (r = 0.49) respectively. Meteorological conditions did not have a significant impact on concentrations of other chemical elements, however, correlation analysis showed that concentrations of BOD7 in streams’ water were increasing as precipitation level was falling (r = 0.41), and PO4 -P – when air temperature was increasing (r = 0.46). It was determined that in every spring the stream’s water quality according to the concentrations of Ntotal and N-NO3 was in a bad or average ecological condition. This was caused by the farming fields from which these streams are collecting drainage water during the spring melt.