REMARKS ON THE EVOLUTION TENDS OF AQUATIC AND PALUDICOLOUS VEGETATION IN THE MAIN ACCUMULATION LAKES IN TIMIS COUNTY PUBLISHEDAlina Neacsu, Gicu Gabriel Arsene
Our research were carried out in the period 2004-2010 and had in view establishing the vegetal associations and indicating the evolution trends of aquatic and paludicolous vegetation in the main artificial water accumulations in Timis County. The data were collected from the accumulation lakes Surduc, Pişchia, Liebling and Sânandrei. In substance, we performed trips on the field during the period indicated, on which occasion we performed phytocoenologic sampling upon which we drew up synthetic charts. The information in these tables was subsequently processed in laboratory. The methodology for field data sampling and processing complied with the principles of the Central-European Phytocoenologic School, established by Braun-Blanquet. Thus, in the area of the above mentioned accumulations were identified 29 vegetal associations, and, also, due to the research period, the vegetation evolution trends could be delineated. Generally, the vegetation succession is the following: it starts from free natant aquatic communities, and, as the aquatic environment enriches in substances, fixed submerse and submerse-natant phytocoenoses appear, then the immerse aquatic vegetation develops and installs, afterwards the paludicolous one. Among the remarks, we noted that the vegetation structure for two of the accumulation lakes studied, more precisely the accumulations Sanandrei and Pischia, has been profoundly changed in the last years, being subject to drainage, for various reasons. These actions had negative impact upon vegetation and biodiversity as a whole. In the past, in the area of these accumulations, suitable growth conditions were encountered by aquatic and paludicolous associations such as those edified of Lemna minor L., Spirodela polyrhiza (L.) Schleichen, Ceratophyllum demersum L., Myriophyllum spicatum L., Polygonum amphibium L., Trapa natans L., Potamogeton natans L., Potamogeton crispus L., Iris pseudacorus L., Glyceria maxima (Hartm.) Holmberg a.o. Following drainage, these associations are not encountered anymore, we noticed that instead a series of weeds appeared. From the biodiversity perspective, this aspect represents a regress, translated into the loss of certain vegetal communities deemed representative for these humid areas.
artificial humid area, aquatic and paludicolous vegetation, dynamics