Phytocenotic and hydrochemical conditions of the new localities of Aldrovanda vesiculosa (Droseraceae) in Chernihiv Polissya.
Aldrovanda vesiculosa is a rare stenotopic species threatened due to destruction of its biotopes. Since the species is protected nationally and internationally, monitoring of its populations is required. Information on growth conditions of A. vesiculosa in three new localities recorded in 2019 and 2020 in lentic (standing water) reservoirs with muddy sediments in the Chernihiv Polissya region is provided. All populations were found in communities of the alliance Utricularion vulgaris. In the first locality (Snovsk, an artificial pond with an area 0.6 ha), the population of A. vesiculosa (projective cover of 10%) occupied an area of 0.5 m × 1.5 m within the shoreline community of the Spirodelo-Aldrovandetum vesiculosae association. In the second locality (Lake Perekop, area 7 ha, in the floodplain of the Desna River) the species was found in an area of 1.5 m2, with projective cover of 25%, also within the Spirodelo-Aldrovandetum vesiculosae communities. In the third locality (Lake Nizhniy Bolhach, floodplain of the Dnipro River), this species was found in an area of 0.5 m2 within the communities of the Lemno-Utricularietum vulgaris association, with projective cover of 3%. The comparison of hydrochemical conditions of biotopes in the found localities and hydrochemical indicators of habitats of this species in the Czech Republic and Poland was carried out. In the first and second localities, the hydrochemical indices are optimal for A. vesiculosa. In Lake Nizhniy Bolhach, some quantitative characteristics of the water chemical composition are beyond the ecological optimum for this species, in particular, exceeded values of hydrogen index (pH 7.0), hardness (12.1 mmol/L), concentrations of calcium (163.039 mg/L) and magnesium ions (49.025 mg/L), while organic carbon content (1214 mg/L) is reduced. A short-term existence of A. vesiculosa in this locality is predicted.