Trapetum natantis Müller et Görs 1960 in hydromeliorative facilities in Serbia

Abstract

<p><em>Trapa natans</em> is one of the very few plants that generate so many contrasting views: it is highly endangered in Europe, invasive in North America and Australia, yet highly valued in India and China due to its nutritional and medical properties. Its endangered status in most of the Europe has prompted significant conservation efforts aimed at retention and expansion of its population. <em>T. natans</em> is currently on the red list of many European countries and is included under “Appendix I” of the “Convention on the conservation of European wildlife and natural habitats” (Bern Convention) and IPA list (IPA criterion A, threatened species). The unusual circumstances, i.e. endangered status of <em>T. natans</em> in the region on one hand and its expansion in Serbia on the other, are the reason behind this research that aims to present the distribution, floristic composition and ecological conditions of ass. <em>Trapetum natantis</em> stands in hydromeliorative facilities (Serbia), comprised of 28 hydrophytes. In the analyzed stands, based on the long-term phytocenological studies, we have singled out four floristic and ecological groups: the stands in which <em>T. natans</em> predominates, the stands with <em>Ceratophyllum demersum</em>, the stands with lemnids plants (<em>Lemna minor</em>, <em>L. gibba</em>, <em>Spirodela polyrrhiza</em>) and Salvinia natans and the stands with <em>Hydrocharis morsus-ranae</em>. In the researched localities, the differentiation of ass. <em>Trapetum natantis</em> stands is predetermined by the phosphorus and nitrate content, as well as pH and BOD₅ levels.</p

The effects of physical-chemical water parameters on the Nymphaeion alliance development in northwestern Serbia

“…Trapetum natantis, is one of the most thermophilic aquatic phytocenoses [21,56,57]. The study findings indicate that the analyzed phytocenosis stands prefer neutral water, which is consistent with the results reported by other authors [6,27].…”

“…The highest dissolved and total phosphorus content, and very wide ecological amplitude of this important parameter, as an indicator of eutrophication, is characteristic of stands in other regions [6,11,45]. In addition to the edificator, hydrophytes S. polyrrhiza [9,12,21,51,54,59], H. morsus-ranae, C. demersum and L. minor [21,51,59] are also well adapted to the eutrophic levels and are widely represented. Within Nymphaeion alliance phytocenoses, the mean value of phosphorus significantly exceeds the limit of "good ecological status" only in habitats of Trapetum natantis stands [50].…”

“…Within Nymphaeion alliance phytocenoses, the mean value of phosphorus significantly exceeds the limit of "good ecological status" only in habitats of Trapetum natantis stands [50]. Moreover, the ability of T. natans to tolerate significant water level fluctuations in the studied hydromelioration facility, in conjunction with the physical-chemical water parameters, is driving its expansion [21].…”

“…Trapetum natantis is the dominant floating-leaved vegetation in the Hs DTD canal network (Fig. 1) [21]. These stands achieve optimal development in the central, deeper parts of the canal (about 3 m), characterized by frequent water fluctuations, as well as in the calm and shallower sections (about 0.5 m).…”

“…were investigated. According to Džigurski et al [21,22], hydromorphological conditions in the studied hydromelioration facility (2-8 m canal depth, variable flow rate and navigation intensity, presence of more than 20 weirs, regulated water level changes, canal age 50-200 years) affect the development of macrophytes differently. Dawson and Szoszkiewicz [23] indicate that Nymphaeion alliance vegetation is typically found in habitats characterized by slow water flow.…”