No abstract

The first results of paleogeographic study at estuary of the Katynka river allow to reconstruct the dynamics of vegetation in this part of the Dnieper floodplain for about 5 millennia and identify some traces of Neolithic, Early Iron Age and Medieval human activity. The most prominent anthropogenic transformation of landscapes (signs of slash-and-burn agriculture) was associated with the late Holocene «Gnezdovo» buried soil dated 2-5 centuries AD.

No abstract

Partially mycoheterotrophic (mixotrophic) plants are considered to be more common among phylogenetic lineages that include fully mycoheterotrophic plants. Gentianaceae is one such group. Mixotrophy is not well known for alpine plants in contrast to species of tropical and temporal forests. We tested the hypothesis that green alpine species from the Gentianaceae family can be partially mycoheterotrophic. Leaves of nine pairs of species (alpine plants from the Gentianaceae + reference neighboring AM plants from other families) were collected in Tibetan (Sichuan, China) and Caucasian (Karachai-Cherkessian Republic, Russia) mountains. Stable isotope ( 13 C, 15 N) natural abundances were determined in fully developed leaves. In each case leaves of Gentianaceae plants were enriched in 15 N more than the leaves of other plants which served as comparisons. Except for two species from the section Pneumonanthe (Gentiana asclepiadea and G. septemfida) the studied Gentianaceae plants did not show significant 13 C enrichment. We suggest that relative 15 N enrichment of leaves may be considered as an indication of partial mycoheterotrophy in alpine Gentianaceae.

The symbiotic association of mycelial fungus with the roots of higher plants (mycorrhiza) has a large and often ambiguous influence on plant communities and their structure. Mycorrhiza acts simultaneously on many features of the community, and, therefore, the assessment of its influence is not an easy task. It requires carefully planned experiments and the use of special methods of statistical analysis. Following a four-year experiment at the high-altitude station of the Moscow State University "Malaya Khatipara" (Teberda Nature Reserve), this article presents the results of data analysis, including two-way replicated analysis of variance (ANOVA). The alpine meadow communities were subjected to treatment with fungicides in order to suppress fungal colonization. It was found that suppression of mycorrhizae always leads to a decrease in the number of forbs dependent on mycorrhizal fungi, an increase in the number of predominantly non-mycorrhizal sedges, and the dynamics of grasses abundance after suppression of mycorrhiza may differ depending on their initial position in the community. Our results also point out the positive role of mycorrhiza in forming species richness in communities of the alpine belt of mountains.