Vol 50, No 3 (2019)

This study deals with the relationship between the species richness of vascular plants in 10 × 10-km plots and climate indices in the Middle Volga Region. The most significant indices have been revealed: precipitation and temperature in March, temperature in October, and winter precipitation, with their combined effect accounting for 74% of variation in species richness. In view of relatively low climate gradients, a special function of total precipitation in March has been used in analysis, which describes the nonlinear dependence of the richness of vascular plants on the amount of March precipitation in the form of a peak. An ecological interpretation of these relationships is given and a species richness map is constructed. It is hypothesized that minor variations of intra-annual temperature and precipitation indices in the area with low climate gradients may become critical factors for the spatial change in the number of vascular plant species.

A comparative analysis of the seasonal formation of tree rings has been performed in Siberian larch (Larix sibirica Ledeb.) and Scots pine (Pinus sylvestris L.), growing in the southern taiga of Central Siberia in two sites on the altitudinal transect (200 and 536 m a.s.l.). Core samples were taken from April to September in 2012. The results have shown that the onset and duration of different phases of tree ring formation in larch and pine are determined by the geographic location of the sites and the related temperature gradient. It should be noted that species-specific features of tree growth have an effect on the formation of xylem cells during the growing period and, as a consequence, on the dimensional anatomical parameters of tracheids.

Modeling of the bioclimatic niches of the complex of tall herb communities in the current and predicted climatic conditions by 2070, as well as in the conditions of the climate of the Last Glacial Maximum (about 21 thousand years ago), has been performed. The most important bioclimatic parameters controlling the geographical distribution of tall herbs are the amount of snow precipitation (snow depth), Kira’s warmth and coldness indices, and the continentality index. Under the conditions of the Last Glacial Maximum, bioclimatic refugia of tall herbs could be preserved on the Kuril Islands, but were absent on Sakhalin Island and Kamchatka Peninsula. Current trends of climate change will lead to an increase of the area suitable for tall herb communities in the Russian Far East, but will reduce their distribution in Japan.

The material for the study was obtained from report forms collected in the course of national census of Eurasian Woodcock during the evening roding period in 2016 (2001 forms) and 2017 (2538 forms). The numbers of reported contacts with roding birds reached 14242 and 17 024, respectively. For the first time, a geostatistical kriging method was applied to this large amount of material to describe the spatial distribution of woodcock population in different years. Plots with high roding intensity and the largest numbers of recorded contacts (on average, more than nine) were identified, and weather conditions in these plots were estimated from satellite monitoring data. The 2 to 9°C isotherms were determined, which spread dynamically and unevenly over the territory of European Russia in 2016 and 2017 and had an effect on the redistribution of the birds. The significance of correlation between the distribution of Eurasian Woodcock population and weather conditions was confirmed statistically.

Lake Piskory is situated in central-eastern (CE) Poland, in the southeastern part of the Vistula River spillway about 7.5 km from the mouth of the Wieprz River to the Vistula River. Prior to 1993 when restoration activities aimed at reestablishing hydrological function and diversifying habitats were implemented, the area was overgrown with rush vegetation and the water mirror seized to exist. In the initial years post restoration, the lake surface area increased and plant diversity grew. However, since 2000 plant diversity has decreased largely due to the rapid growth of Carex and Phragmites, and the lake is once again being overgrown. Here we document changes in vegetation and water hydro-chemical features from 1993 to 2015 and compare land-use activities from 1973 to 2015 to better understand the causes and implications of these changes. The surface area of the lake varied throughout monitoring years, particular plant communities fluctuated, from 2005 to 2010. During dry years the area of reed rushes visibly grew, while the extent of valuable underwater stonewort meadows contracted and disappeared. Man-made ecosystems often require continuous management action. If active management is not taken in the Lake Piskory region, complete overgrowth of the system is once again possible and the system may transition into a novel ecological status.

The transformation of ecosystems influences the genetic diversity and evolution of aquatic organisms. However, the mechanisms by which the genetic structure of the Daphnia population responds to the changes in ecosystem remain unclear. We used the mitochondrial cytochrome oxidase subunit (CO1) and 12S genes and microsatellite markers to investigate the genetic structure and differentiation of the Daphnia similoides sinensis population in the sediments (core depth, 25 cm) of Lake Junshan, China. The construction of a lake embankment in 1958 changed the lake ecosystem from an open to a closed state, interrupting species exchange and thus leading to a continuous decrease in the genetic diversity of the D. similoides sinensis population during 1959–2010 (14-3 cm), although its genetic structure was stable based on the analysis of 14 microsatellite markers. However, after 2010, the genetic diversity indexes showed an increase in the genetic diversity of D. similoides sinensis; there was also a significant change in the genetic structure. The changes in the genetic diversity and structure of D. similoides sinensis significantly correlated with eutrophication. The results suggest that lake embankment can reduce the genetic diversity of D. similoides sinensis during the early stages. The D. similoides sinensis population accelerated genetic differentiation during the rapid lake eutrophication period due to continuing barrier effect. This study clearly reveals the effects mechanisms of the rapid enclosure of aquatic ecosystems on the species diversity and genetic differentiation of aquatic organisms.