Contemporary Problems of Ecology最新文献

Abstract

The results of an 8-year study of the Platanthera bifolia (L.) Rich. (Orchidaceae) population on the northern border of its range (the Komi Republic, northeast of the European part of Russia) are presented. A negative correlation is found between the size of the leaves of this species and precipitation at the beginning of the current growing season. The number of flowers and their sizes are influenced by the weather conditions of August of the previous growing season. There are no significant differences in plant height or inflorescence length over the years. The number of the population is high for this species (400 plants); it is negatively affected by a lack of moisture in the previous year. Observations of mapped individuals reveal the duration of the presence of plants in different phases of ontogenesis. The ontogenetic spectra of the studied population correspond to the basic spectrum of the species; in some years, the dominance of juvenile specimens is observed, which is associated with the renewal waves characteristic of the species. Pollination efficiency is not affected by the number of flowers in the inflorescence or their size; it is related to the level of moisture availability of the territory. Seeds of P. bifolia (0.60 × 0.13 mm) in the studied area are smaller than in the southern parts of the range of this species. Significant differences in the size of seeds in different years of the study are revealed; the main influence on them is the weather conditions of July. A tendency to an increase in the volume of air space in the seed in wetter years has been found, which contributes to their better distribution under adverse weather conditions. Real seed productivity of P. bifolia varies by year from 25 400 to 40 800 seeds; this indicator is associated with the level of moisture availability of the current growing season. The presence of juvenile individuals (18.3–51.8%) in all years of study indicates successful seed renewal in this population. The number of juvenile individuals correlates with the moisture level of the previous growing season.

Abstract

Despite the availability of more and more data on Arctic biotic communities, even the principal course of their transformation remains unclear. Differences in the population dynamics of geese, lemmings, and ruminants covering more than 98% of the Arctic terrestrial ecosystem recycling and competing for common trophic resources on the basis of specialization are of great interest. Comparing 15 species of the taxa, we showed that grades of their morphophysiological adaptation to phytophagy are matched to empirical estimates of their food selectivity, thereby describing their trophic specialization distribution. Thus, in the Arctic herbivore communities, the selectivity distribution is just as stable as specialization. Populations of trophic specialists in these communities, the most glaring examples of which are the muskox and the snow goose, generally exceed in size and/or growth rate the populations of generalists, which include lemmings and the smallest black geese. The specialist populations have mainly higher size and/or growth rate than the generalist populations. It may be concluded that interspecific competition influences the contemporary transformation of the Arctic herbivore communities much more strongly than environmental factors such as global warming and human activity do.

Abstract—This study was performed to decide the optimum sampling area by estimating minimum sampling areas (MSAs) in the Sarıkaya Wildlife Reserve Area (WLRA) of Western Taurus, the richest endemism center of Turkey and containing almost all Mediterranean vegetation layers. Data were taken from 20 standard sampling plots of 32 × 32 m (1024 m²). Standard sampling plots were divided into subplots, and plant data were recorded from each one. Then the subplots were combined from the minimum subsample plot to the last largest one by adding the newly detected species. Four unsaturation curves and two saturation curves (i.e., power function (FP) and exponential function (FE)) were employed to estimate MSAs of the sampling plots. The upper limit value of estimated species richness, (S_{t}^{'}) obtained from the Michaelis–Menten (MM) model and the Hanes–Woolf (HW) model was used in MSA equations of the saturation curves for each sampling plot. The goodness-of-fit measures were generated using the corrected Akaike Information Criterion (left( {AI{{C}_{c}}} right)). Saturation curves, particularly exponential function, provided most of the best fit models. The findings indicate that the size of the optimum sampling area for obtaining sufficient information about plant diversity should be equal to or greater than 900 m² in the study area.

Abstract

This work presents the results of studies of the emergence of amphibiotic insects from the old beaver pond on the Yuzhnaya River of the Privolzhskaya Lesostep Nature Reserve in the Upper Khoper basin. The parameters of abundance, biomass, and frequency of occurrence are given for insects from 34 families and 8 orders; the timing of their emergence in different parts of the pond is indicated. The dominant and common species are identified: chironomids Paramerina cingulata (Walk.) and Cricotopus silvestris (F.), biting midges (Bezzia bicolor (Mg.)), chaoborids Chaoborus flavicans (Mg.), and mayflies Cloeon inscriptum (Bgtss.). The intensity of the emergence of insects is 12.10 individuals/m² per day; the average daily transfer of biomass is 49.23 mg/m² per day. The analysis of the fatty acid composition and content of the main biogenic elements in adults of amphibiotic insects is carried out. The results of calculations of the energy and matter transfer, including biogenic elements (carbon, phosphorus, and nitrogen) and polyunsaturated fatty acids (PUFAs) during the emergence of insects from various orders (Ephemeroptera, Odonata, Trichoptera, and Diptera) into adjacent terrestrial ecosystems, are presented. The transfer of wet biomass from water to land is 7.385 g/m² per year and, in dry weight, 2.216 g/m² per year; transfer of the main nutrients is carbon, 1.21 g/m² per year; nitrogen, 0.25 g/m² per year; and phosphorus, 0.03 g/m² per year. PUFA transfer is 24.16 kg/km² per year.

Abstract

This paper discusses the species composition and population structure of small mammals inhabiting the north-taiga landscape of the Nadym Hills (Yamalo-Nenets Autonomous Okrug, Russia) with an emphasis on catenary patterns in the intralandscape differentiation. Five small mammal species (Cl. rutilus, S. caecutiens, S. araneus, A. oeconomus, and E. sibiricus) typical for the north-taiga subzone of Western Siberia are recorded in different parts of a northwest-facing landscape catena (upland, saddle, slope, and floodplain). In terms of abundance, the northern red-backed vole (Cl. rutilus) predominates in all catena localities and in the landscape as a whole. Other species codominate in certain localities, with the exception of S. araneus, who is common only on the upland. Throughout the entire study area and in the upper localities of the catena, Cl. rutilus and S. caecutiens form the core of small mammal communities. The total abundance of small mammals and the abundance of the dominant species gradually decline along the slope (i.e., from the upland to the floodplain). Resident and propagating small mammal populations are present in all catena localities. The composition, structure, and parameters of small mammal communities change along the slope following changes in afforestation, wetting, plant species richness, vegetation structure, and microtopography. In all catena localities and throughout the entire study area, small mammal communities feature low values of the diversity, evenness, and sustainability indices and high values of the dominance index, which is determined by harsh natural and climatic conditions. However, their generally undisturbed structure is typical for natural subarctic communities, which indicates their sustainability.

Abstract

Specific features of the organic matter transformation in peat eutrophic soils (Hypereutric Sapric Histosols) and peaty gleezems (Eutric Histic Gleysols) 20 years after a forest–peat fire are discussed within the ecological direction of studying humus using traditional methods and terms. The study object is represented by a green-moss–hypnum spruce forest (Picea obovata Ledeb.) on the eastern slope of the Kuznetsk Alatau (at the altitude of 622 m above sea level). The composition of organic matter of pyrogenic soils (0–30 cm) is characterized by high variability (the variation coefficient is 12–92%). According to the factor analysis, the total variance is related to a combination of humic substances (76%) and to polysaccharides (24%). Cluster analysis enables us to identify two groups of objects, and their statistical reliability is confirmed by the discriminant analysis. Soil clusters reflect the peculiarities of pyrogenic processes: underground focal smoldering below the point of ignition and open intensive and moderate fire. Carbon content decreases to 26.5 and 13.4%, respectively, relative to the background (41% in peats not affected by fire). The formation of humification products is almost equal: (∑HA + ∑FA) is 55.4 and 53.7%, mainly due to fulvic acids (C_HA/C_FA = 0.2–0.6). The peculiarity of the thermal effect is mainly seen at the fractional level. The specificity of underground smoldering consists of an increased formation of fulvic acids of the first fraction free and loosely bound to R₂O₃. An open fire is accompanied by the predominating formation of humic and fulvic acids bonded to calcium. According to standardized coefficients of canonical analysis, the first and second fractions of humic and fulvic acids make the greatest cumulative contribution to cluster discrimination, and the maximal personal weight is related to HA-2, FA-1, and FA-2. Based on previously obtained data on the group composition of buried peats and the important role of anaerobiosis in the formation of humic acids, which better correspond to the restored substance when compared to fulvic acids, it may be assumed that peat formation, continuing in the fire area, can cause the transformation of fulvate humus into fulvate-humate and/or humate one. In the case of burial of a pyrogenic peat layer 0–30 cm in thickness, the transformation may occur over about 270 years, taking into account the rate of linear peat growth in spruce forests of the Kuznetsk Alatau: 1.12 mm/year. The research results confirm that the traditional division of humic acids into fractions is reasonable.

Abstract

The effect of molting anseriform birds on the structure and elemental composition of phytoplankton (seston) has been assessed in 20 Arctic lakes of the Taimyr Peninsula. In lakes (part of the lake) inhabited by ~50–700 birds of six species, the average stoichiometric ratio N : P (mol : mol) was statistically significantly lower than in lakes without anseriforms: 15.8 ± 1.4 and 22.4 ± 2.7, respectively. There was also a tendency of higher average specific electrical conductivity in the lakes with the birds, 113 ± 32 µS/cm, when compared with those without anseriforms, 60 ± 18 µS/cm. The differences could be explained with high probability by the effect of guanotrophication, namely, by a flow in water of metabolites of molting anseriforms. The total biomass of phytoplankton and proportions of algal taxa and cyanobacteria in the total biomass did not differ statistically significantly in lakes with and without molting anseriforms. Therefore, under guanotrophication, the main threat of eutrophication was absent: an increase of biomass of cyanobacteria, causing the nuisance “bloom” of water. Moreover, an opposite tendency occured: in lakes with molting anseriforms, the proportion of cyanobacteria in total biomass of phytoplankton was on average lower than that in lakes without the birds, 16.2 ± 5.3% and 30.8 ± 9.3%, respectively. Thus, a hypothesis was confirmed that artificial guanotrophication should be regarded as a suitable ecotechnology for the increase of productivity of oligotrophic Arctic lakes.