Οικολογία των τύπων οικοτόπων της αποξηραμένης λίμνης Μουριάς

Abstract

The area of the drained Mouria lake is located 5Km SW of Pyrgos city (Prefecture of Ileia) near Alfeios River estuary. It was drained during the period 1967-69. Subjects of the present thesis are: a) the study of the flora in the drained lake area, the identification and the mapping of the habitat types, b) the estimation of the vegetation units degradation degree by various human activities, c) the correlation of the vegetation units with certain environmental parameters (soil and water physicochemical parameters), d) the pilot-scale re-flood of a part of the drained lake (0.5 ha) in order to estimate the colonization rate by plant species in the new lake. Seasonal vegetation samples were taken from the whole area of the drained Mouria Lake, following Braun-Blanquet method. Habitat types were identified and their limits were determined by means of GPS. In order to study environmental parameters soil and water samples were taken in sites where vegetation samples had already been taken. After the floristic analysis, vegetation units were detemined. The abundance of indicator plants of habitat degradation (grazing indicator plants, weeds and ruderals) in each habitat’s floristic composition is used in order to evaluate their ecological status. Correlations between environmental parameters were tested using Spearman correlation test, while Canonical Correspondence analysis (CCA) and Factor analysis were performed in order to examine relationships between the vegetation units and environmental variables. For a pilot-scale lake restoration an area of 0,5 ha was selected in the SE part of the former lake to be re-flooded. A total of 284 plant species were recorded in the are of the drained lake, 144 of which are characterized as indicator plants of habitat degradation. Seven habitat types and sixteen plant communities have also been identified in the study area. Salt meadows, reeds and Tamarix stands have the biggest cover in the area. Salt meadows appear to have the highest degree of degradation and the temporary ponds the lowest. The plant communities of sand dunes and these of wet dune slacks are formed in sandy soil, rich in CaCO3 and Ca+2 and with high pH values. The salt meadows communities are developed in various types of soils (sandy to loamy-clay) with high electric conductivity values and high phosphor concentrations. The soil moisture and the NO3- concentration are the most important factors that influence the growth of communities with Tamarix sp. Temporary ponds present a combination of high salinity, alkalinity and nutrient concentration values in the area. Phragmites australis community is developed on sites with higher water salinity values than Typha domingensis community. The study of vegetation succession in the pilot-scale wetland shows that many plant species of the nearby temporary ponds and channels like Ruppia maritima, Zannichellia palustris, Chara sp., Ranunculus baudotti etc. have rapidly colonised the new lake .