Trapa Natans L. S.l. Growth Features In Desna River Basin
Abstract
Iu. L. Skliar, V. H. Skliar
Trapa natans L. s. l. is a typical representative speciesof the ecological group of attached higher aquatic plants with floating leaves. It is included to The Red Book of Ukraine. Despite the presence of diverse information on the main features of the structure of the vegetative and generative organs of Trapa natans, its ecological properties, distribution and significance, population and growth characteristics of this species remain virtually unexplored. We evaluated 10 morphometric and five allometric parameters, which characterize the growth of Trapa natans and found out the influence of leading ecological-coenotic factors on them: the thickness of water, its transparency and the overall projective coverage of phytocoenosis. Four old lakes, which located in the flood plain of the Desna River are covered by our studying. Grouping represented in these lakes are significantly different by degree of their rarity, as well as by the specific gravity and role of T. natans plants in their composition. The association Nuphar lutea subpurum is one of the typical for the region and the most common, the other three (especially Nuphar lutea + Nymphaea candida variant with Trapa natans) are comparable rare. The results of the studies showed that the water column factor significantly affects the values of all 15 dynamic morpho-parameters. The transparency of water factor did not show a statistically significant effect on the values of two morpho-parameters, and the projective coverage - at the value of three. For most morpho parameters, the power of influence on them of water levels are in the range of 45-75%, transparency - 25-60%, and projective coverage - 20-60%. It is shown that the greatest values of dynamic morphological parameters belong to the coenopopulation from the group Trapa natans subpurum, and the smallest to Nuphar lutea subpurum. Trapa natans better growth in reservoirs with a water column about 145 cm and its transparency about 80 cm, no current and muddy bottom sediments. It is noted that the effective natural inhibitors which are regulating the growth of Trapa natans are the reduction of water levels in the water column and the occurrence of successional processes that are accompanied by an increase the number of species of Nymphaeaceae in phytocoenoses.
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