| Abstract [eng] |
The knowledge about factors, which influence the abundance and distribution of species are the main goal of ecological explorations (Sztatecsny et al. 2004). The main goal of this master thesis was to evaluate which biotic and abiotic factors are the most important for the survival and reproduction of Lithuanian newts. Inasmuch it is claimed, that the needs of T. cristatus and T. vulgaris are similar the question raises: why one species is able to survive and the other one is declining? Research carried out during this work is trying to answer this question. The data were collected in Southwestern Lithuania and adjacent Polish areas. The research was carried out in July 2005 (21 pond) and July 2006 (74 ponds including the same 21 from the previous summer). Ponds were evaluated according to their main structural and habitat factors using standartised evaluation form. Firstly the ponds evaluated during summer 2005 and summer 2006 were compared since there was a drought in Lithuania in the summer 2006. It was ascertained, that the drought did not have any influence for the abundance newts‘s larvae in the ponds, that did not dry out. Furthermore it was found out that the shadow percentage on the pond‘s surface had an influence for the occurence of both species. Optimal shadow percentage was 25 – 50 % for T. vulgaris and 50% for T. cristatus. Moreover, it was ascertained that the most important habitat factors for T. vulgaris are: water colour, amount of the floating, submerged and used for the egg laying vegetation. Premetamorphic T. vulgaris and Rana habitats were found to be similar. The most important factors for T. cristatus are: the amount of submerged vegetation, presence of deciduous forest, distance to the forest and the amout of ponds in the 100 m distance from the evaluated pond. The presence of fish influences negatively the occurence of the both newts species. Both living in Lithuania newt species need similar conditions. |
