Search Results (2)

Previous studies provided evidence of the mixing of boreal–tropical cladocerans (Crustacea) in the Far East of Eurasia, as well as the presence of numerous pre-Pleistocene relict endemics. In this study, we hypothesize that the colonization history is reflected in the proportions of endemic/boreal/tropical taxa among different habitat types within this region. We analyzed 442 qualitative samples collected from seven sub-regions of the Far East of Russia and South Korea along a latitudinal transect of approximately 2200 km, where we identified 101 Cladocera species. Our results showed a significantly higher proportion of endemic taxa in the plankton compared to the littoral and benthic zones. The proportions of endemic/boreal/tropical taxa in the permanent and temporary waters were similar. We observed a distinct shift in dominance in benthos and littoral zone across our transect: boreal taxa were prevalent in the northern sub-regions (1–4), while tropical taxa were prevalent in the southern sub-regions (5–7), with a pronounced boreal–tropical transition zone (sub-regions 4–5). Our findings suggest that this pattern arose due to the unhindered dispersion of the two faunas in a latitudinal direction until they met at the boundary during their arrival in the Late Pleistocene. In contrast, the proportions of the boreal and tropical taxa in plankton did not exceed 16% in any of the studied sub-regions, and the proportion of boreal taxa decreased from 16% to 10%, while that of the tropical taxa increased from 0% to 10% from north to south. We propose that the lower proportions and the absence of mixing of fauna in the plankton can be explained by the strong presence (sometimes dominance) of relics that occupy these water bodies before the arrival of colonizers from the north and south. Our findings highlight the significant role of biotic interactions in the formation of biogeographic boundaries, which was previously underestimated. Full article

Anthropogenic transformations of habitat conditions in moderate climate peatlands frequently cause a decrease in the number of sites of occurrence and the size of the population of many valuable plant species, including the boreal relic Betula humilis. The objective of this paper was an attempt to relate the specifics of the occurrence of the glacial relic Betula humilis in the peatlands of Central-Eastern Poland, which developed under moderate climate conditions, to the conditions of the natural environment identified through research into the physical and chemical parameters of the groundwater, as well as botanical research into its habitat. The study results confirm that shrub birch has a broad range of ecological tolerance to the majority of the studied factors and can therefore be an indicator of habitat transformation. Important environmental factors affecting its abundance are water relations and the contribution of calcium hydroxide and phosphorus fractions. A condition favouring the proper functioning of individuals of the studied species is TP values lower than other obtained values, in the following range: 0.08–0.32; P-PO₄: 0.1; TN: 2.2–21.2; N-NH₄: 0.1–0.46; DOC: 24.6–55.9 (mg·dm⁻³), as well as higher than average pH values, in the following range: 5.34–5.95; Ca: 5.67–28.1; Mg: 0.56–2.41 (mg·dm⁻³) and EC: 72.1–142.3 (µS·cm⁻¹). Full article