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Habitat requirements of Elodea canadensis Michx. in Polish rivers

Cegłowska A., Jusik S., Samecka-Cymerman A., Klink A., Szoszkiewicz K.

Oceanological and Hydrobiological Studies

2017

Vol. 46, No. 4

363--378

The main objectives of this work were to investigate the range of habitat conditions (in terms of water chemistry and hydromorphological parameters) at sites colonized by Elodea canadensis and to analyze the species composition of communities with this plant species. We analyzed physicochemical, hydromorphological and biological data from 1135 sites located in Polish rivers to identify environmental factors that determine the occurrence of Elodea canadensis. Canadian waterweed was present at 18.1% of the analyzed river sites, located mainly in the lowlands (26.2% of all lowland sites).The results show that Elodea canadensis prefers moderately mineralized water (545 ± 329 μS cm−1), rich in calcium and magnesium carbonates (174 ± 63 mg CaCO3 |−1, 84.1 ± 31.4 mg Ca2+ |−1 and 11.1 ± 6.4 mg Mg2+ |−1), with moderate concentrations of chlorides and sulfates (38.9 ± 59.1 mg Cl−|−1 and 62.3 ± 50.9 mg SO42- |−1) and in terms of nutrients, it prefers water from moderately rich to mesotrophic and eutrophic. This plant has high light requirements and grows mainly in unshaded sections of shallow rivers. The studied species avoids sections of rivers strongly transformed and those with reinforced banks and bottoms. Canadian waterweed occurs mostly in the company of vascular macrophytes associated with slow-flowing rivers with sandy bottom material, indicating mesotrophic and eutrophic water.

Coexisting aphid (Hemiptera: Aphididae) and ant (Hymenoptera: Formicidae) communities : interdependence in various habitats

Depa Ł.

Polish Journal of Ecology

2011

Vol. 59, nr 4

835-840

The paper presents the comparison of species diversity and evenness indices calculated for coexisting communities of aphids and ants. In six study areas, localised in Upper Silesia (Poland), representing acidophilous oak-forest (Molinio caeruleae - Quercetum roboris), moist meadow (Molinietum caeruleae) and xerothermic grassland (Sileno-Phleetum) the community structure of aphids and ants (species number and abundance) was determined. The number of ant nests and aphid colonies was determined by searching the squares of 25 m2 during vegetation seasons in 2006 and 2007. This provided the base to calculate the Shannon.s diversity index and evenness index of both groups. Spearman's rank correlation analysis showed significant correlation only in the case of the number of species of both groups in a particular study area. It showed no significant correlation of values of diversity and evenness indices; however, considerable differences of values between both groups in various habitat types were recorded. The results are discussed with reference to the habitat history and maintenance, also reflecting the mutualistic relationship between ants and aphids.