Vol 12, No 4 (2019)

The radial increment of Abies sibirica Ledeb. and mortality dynamics of fir stands in the mountain forests of the Eastern Sayan (Stolby State Nature Reserve) have been analyzed. The unprecedented decline in fir stands is caused by water stress due to an increase in air temperature and synergy with the impact of the Polygraphus proximus Blandford. This xylophage was not previously observed in the Abies sibirica range. In the initial phase of climate warming, an increase in radial increment was observed, which was replaced by a depression in 1985–2017. The declining of fir trees was preceded by an increase in the relationship between growth index and SPEI, as well as between the growth index and root-zone moisture content. At the same time, the growth index of the declining cohort was more closely associated with the root zone moisture content (r² = 0.56) and SPEI (r² = 0.74) than the growth index of the surviving cohort (r² = 0.15 and r² = 0.39, respectively). The decline in fir began in the 2000s, when Polygraphus proximus Blandford attacked trees Abies sibirica. During this period, dead stands were localized mainly on the relief elements with the highest probability of water stress (steep slopes located in a “rain shadow”). By 2017, the decline spread throughout the entire territory of fir stands, which led to the mortality of ~75% of fir stands. During the period of tree decline, a close relationship was observed between growth index and fir mortality (r = –0.79). The surviving trees grew under conditions of a higher root-zone humidity (compared to declining trees). The proximity of growth-index trajectories of cohorts of declining and surviving trees, which indicates the probability of mortality of surviving trees in the context of a predicted climate aridity increase, is noteworthy.

Quantitative relationships between the active acidity \({\text{(p}}{{{\text{H}}}_{{{{{\text{H}}}_{2}}{\text{O}}}}})\) of peat soils on the one hand and their exchange acidity (pH_KCl), nonexchangeble (total potential) acidity (1M CH₃COONa extract), contents of exchange cations and alkaline-earth bases, and base saturation degree, on the other hand, have been identified in the form of a linear function. Coefficients of the resultant regression equations are provided. The high predictive capability of the produced regression models is proven using independent data as examples. The use of regression equations eliminates the need for time-consuming chemical analytical works, thus making it possible to operatively classify wetlands and peat soils on the basis on their chemical properties: saturation with alkaline-earth bases and pH value. The botanical composition may also be used as a reliable indicator, provided that the degree of peat decomposition is low and subject to special knowledge of morphology and anatomy of sphagnum mosses and vascular swamp plants.

This study analyzes the ecological patterns of the altitudinal belts of differentiation of avian fauna and population in the mountains of northeastern Siberia. Data were collected during expeditions conducted in the summers of 2014–2016 in regions with distinct forest, subalpine, and alpine altitudinal belts. There are 150 species of breeding avifauna in the region. We have specified the distribution ranges of 26 bird species. Avifauna of the northeastern Siberia mountains develops in a framework of general zonal–landscape and altitudinal zonal patterns. The species diversity of birds decreases in the northern direction and from foothills to the mountain tops. The forest belt, subalpine belt, and alpine belt are breeding areas of 63–64 species (89–97%), 13–33 species (20–47%), and 8–15 species (12–21%), respectively. The wide vertical distribution of many bird species predetermines great general biodiversity, even in high-altitude belts with extreme environment conditions. In the northeastern Siberia mountains, the population density of birds and their abundance progressively decrease with altitude in most species. The bird population density is 312–594 ind./km² for the forest belt, 57–266 ind./km² for the subalpine belt, and 40–111 ind./km² for the alpine belt.

The patterns of structural transformation in forest rodent communities of Sakhalin have been considered using data from long-term comparative studies of two communities of a somewhat similar species composition. An analysis of species abundance dynamics and dominance structure show that the monodominant community structure in northern Sakhalin is characterized by the absence of interannual rearrangements and high stability, with the overall animal number in rodent communities dependent only on the abundance of the northern red-backed vole (M. rutilus). The community in the southern part of the island could assume one of the two structural types: the monodominant structure with M. rutilus or the gray red-backed vole (M. rufocanus) prevailing or a bidominant structure with both species acting as codominants. The numbers of secondary species vary independently of the numbers of dominant species. Changes in the abundance of M. rutilus and M. rufocanus within the same community are synchronized, whereas the population cycles of these species in the southern and northern communities are not conjugated.

The steppe and semidesert landscapes of the Republic of Kalmykia and Rostov oblast (a total of 12) in various ecological and geochemical conditions (precipitation, temperature, soil salinization, position in meso and macro relief, etc.) have been studied. Samples of vegetation and soil have been taken at the selected sites, and the contents of P₂O₅, MgO, Al₂O₃, K₂O, CaO, TiO₂, MnO, Fe₂O₃, S, Sr, Ba, Zn, and Ni are measured by the X-ray fluorescent method. Organic carbon (C_org), calcium carbonate (CaCO₃), pH, and granulometric composition are additionally determined in soil. To estimate the absorption and biogenic accumulation of chemical elements by vegetation, the coefficient of biological uptake (CBU) is calculated. To interpret and visualize the data, the nonmetric multidimensional scaling method is used. It is revealed that when environmental conditions vary the content of chemical elements in the studied plants decreases as following: Sa > Al > Fe > K > S > P > Mg > Ti > Mn > Sr > Ba > Zn > Ni. The highest contents of Al, Fe, Mg, Mn, Ti, Ba, Zn, and Sr are shown for plants of the genus Poaceae Barnhart, and the highest contents of Ca, K, P, and S are shown for plants of the genus Artemisia L. According to the cumulative characteristics, concentrations of the studied elements in vegetation are significantly different from each other in aboveground parts of cereals, aboveground and underground parts of wormwoods, and underground parts of cereals. For the studied plant species, the coefficient of biological uptake of chemical elements >1 was revealed for S_(1.1–12.7), Zn_(0.2–6.5), K_(0.1–3.9), Ca_(0.1–3.5), Sr_(0.1–3.0), and P_(0.2–1.3).

Climate change has been identified as one of the most important and immediate threats to biodiversity. In this study, we reviewed published papers about the impacts of climate change on Iran’s biodiversity since 2014. We found that among the 37 studied species, 30 species will lose at least some parts of their distribution ranges. However, the distribution of seven species will increase. Climate change will have negative impacts on 81 percent of the studied species thus, it is a major problem for biodiversity conservation in Iran. We suggest that determining the effectiveness of Iran’s protected areas for conservation of biodiversity, and ensuring their connectivity under current and future climatic conditions should be prioritized for future research in Iran.