Sirvi Autor "Lesta, Merje" järgi
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Kirje Avaveeliste märgalapuhastite rakendamise eelduste analüüs Eestis(2004) Lesta, Merje; Mander, Ülo, juhendajaKirje Evaluation of regulation functions of rural landscapes for the optimal siting of treatment wetlands and mitigation of greenhouse gas emissions(2009-11-20T11:17:32Z) Lesta, MerjeIn order to implement sustainable landscape planning, it is essential to have knowledge of landscape ecology and landscape evaluation principles. In this PhD dissertation we have proposed a few landscape evaluation methods in the context of regulation functions (waste treatment, water regulation, gas regulation etc.) of rural landscapes. A GIS-based method of complex landscape analysis has been developed in order to estimate the landscape suitability for the construction of surface flow wetlands (SFW) for wastewater treatment. The two-step assessment scheme consists of landscape classification according to the physical–chemical properties of landscape factors, expert decisions concerning landscape values, and suitability analysis. The analysis was carried out both, on regional and on local level, using various digital cartographic data. Resulting thematic maps would support decision making and provide more dynamic planning process. Potential areas for reconstruction of current point pollution sources or their provision with treatment wetland systems have been determined. This method demonstrated that in Estonia the share of very suitable areas for the construction of SFWs covers 16% of the entire country, and the share of suitable areas covers 25%. In addition, the suitability evaluation of areas on hydromorphic soils for treatment wetland creation with additional function of raw material production, was carried out. Annual biomass production was evaluated and the standing stock of N and P in the phytomass of broad-leaved cattail and reed was determined. The average aboveground biomass of cattail and reed varied from 0.3 to 1.8 kg DW m−2 and 0.6 to 1.3 DW m−2 respectively. The nutrient removal by cattail was considerably high. Cattail biomass has a large temporal and spatial variation in productivity, which makes it somewhat difficult to use them as a raw material for building and fibre production. According to executed GIS-analysis, there are 5412 km2 of potentially suitable sites for energy and treatment wetland creation. As part of the regulation function, greenhouse gas CH4 and N2O emissions from the main land use types of rural landscapes were estimated. The annual exchange of CH4 and N2O between the soil and atmosphere was estimated depending on the land cover types and different soils in Estonia. Natural peatlands and marshes appeared to be the most important CH4 emitters, whereas N2O is emitted mainly from drained peatlands and marshes, set aside areas, conventional arable lands, fertilized grasslands, and coniferous and mixed forests – all on hydromorphic soils. The estimated median value of annual CH4 and N2O fluxes for Estonian rural landscapes are 25,519 and 11,050 t respectively. For the optimization of GHG fluxes, avoidance of drainage on peatland soils, preferred development of organic agriculture, and plantation of shortrotation energy forests and energy crops could be mentioned. The GIS-based assessment of landscape functions serves as a promising tool for sustainable landscape planning and management allowing multi-functional land use and supporting sustainable development.