Russian Journal of Ecology

The validity of some concepts underlying the enemy release hypothesis was tested using the example of Acer negundo, an invasive tree species in Eurasia. For this purpose, the frequency of leaf damage and the proportion of leaf area removed by phyllophagous invertebrates were compared between A. negundo and two native species, Betula pendula and Salix caprea. The leaves of these trees were collected in the city of Miass, the Southern Urals, where three rounds of sampling were carried out in the same habitats during the same growing season. A total of 10 000 leaves were examined to record damage by leaf chewers, miners, or gall makers, other kinds of damage, and the proportion of removed leaf area. By the end of the growing season, the proportion of damaged leaves in A. negundo was estimated at 37%, compared to 66% in B. pendula and 78% in S. caprea, with damage by specialized endophagous species (leaf miners and gall makers) in the first species being very low or absent; the proportion of removed leaf area (relative to the total) in A. negundo was less than 1%, compared to 5.8% in B. pendula and 7.5% in S. caprea. Thus, the level of leaf damage by phyllophagous invertebrates in A. negundo growing in the Southern Urals proved to be lower than in tree species native to this region. Therefore, the absence or low activity of natural enemies for A. negundo may be one of the factors accounting for the success of its invasion in Eurasia.

In the series of phytocenoses from low bush to large-bushy tundra (Vorkuta district, Republic of Komi), with an increase in the shrub layer, the structure of nematode communities changes, as does their number and diversity. Among the trophic groups, a change in the number of bacterio-, myco-, and phytotrophs corresponded to the general tendency. Predators showed the opposite trend, while the abundance of polytrophs did not differ much in the studied areas. Differences in nematode communities are associated with changes in the hydrothermal regimen and chemical properties of the soil. Ecological and faunistic indices, calculated based on data on the abundance and diversity of nematodes, indicate a low level of organic matter in the soil food network and an equal proportion of fungal and bacterial decomposition patterns. However, additional verification of the efficiency of these indices in tundra ecosystems is required.

This work reconstructs changes in the Holocene paleolandscape, plants, and climate conditions of the Upper Kama Region based on integrated analysis of data collected through paleochannel, palynological, paleocarpological, and radiocarbon methods. The selection of these methods is determined from the objective to reconstruct paleoenvironmental conditions of human settling in this region. Parallel use of archeological and natural science methods has proved to deliver good results, while comparison of the findings revealed spatial patterns in the distribution of archeological sites of different ages and allowed detailed reconstructions of the Holocene paleoenvironment.