Model Study of Urban Plant-Soil Complex in Dragalevtzi Experimental Base, Sofia University “Kl. Ohridski”

摘要

The urban territories cause an enormous ecological footprint, affecting resources and biodiversity far beyond the cities boundaries. The urban revitalization therefore involves creation of habitat classification and methods developing for their assessment and optimization to supply services within the cities. The main aim of research is to demonstrate a model for the urban territory assets and services assessment. The indicators used are: water-physical properties of soil, dynamics of soil water supply, spectrums of biological types, life forms and floral elements, phenology, primary production and its quality – biomass fractions participation, nitrogen and crude protein content. The object relates to the J6 habitats sub-group by EUNIS habitat classification. Two experimental variants - fertilized and non-fertilized maize culture (variety Kneja – 509) are used. The obtained results show decreasing of Vertisols water capacity, its monthly dynamics, weed species richness and biological competition at fertilization, which reflects on the water supply and water potential. The biological spectrum is dominated by the perennial plants, the life spectrum – by the hemicryptophytes and terrophytes and the geoelements spectrum - by Euro-Asian and synantropic species (mainly apophytes). The rapid vegetative phase of maize onset, the differences in the sub-stages participation and a month earlier onset of weeds flowering are observed at fertilization. The duration and extent of mass occurrence of phenophases vary specifically for each weed species. The reported average production increases, respectively 1.8 and 1.3 times for maize and weeds at fertilization. The biomass structure is also changed at fertilization - the maize aboveground and the weeds belowground biomass increase compared to non-fertilized plot and vice versa, perhaps due to the weeds striving to capture the mineral elements better than the culture do. The changes of weeds dominant structure are also been observed. The estimated amount of nitrogen in the total production of maize decreases, while this of crude protein increases at fertilization. The indicators and indexes considered in the conducted model study are very sensitive to the cultivation practices and to the variation in the environmental factors. In the same time they are important characteristics of ecosystem functioning and they are widely used in the scientific investigations. However, their development as a complex application for the assessment of assets, capacity and potential of ecosystem services supplied from urban habitats is the originality of the study. They can also be applied to the urban habitats modeling and monitoring.