Impact of point polluters on terrestrial ecosystems: Methodology of research,experimental design,and typical errors

The current state of the ecology of the impact regions is outlined. It is argued that the complex of ecosystems situated around a point polluter (an impact region) is an appropriate model for solving several fundamental and applied ecological problems related to the exploration of strong external impacts on biota. Typical methodological errors resulting from insufficient attention to specific features of passive experiments are analysed, and ways to avoid them are proposed. The principles of spatial arrangements of study sites within the impact region and of the selection of experimental and evaluation units are discussed.     

Changes in the structure of chortobiont invertebrate community exposed to emissions from a copper smelter

The aboveground phytomass of meadow plants and the density of chortobiont invertebrates in secondary upland meadows were estimated using a biocenometer in three areas differing in the level of pollution with emissions from the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast) in 2006 and 2007. As the smelter is approached, the total amount of phytomass (dry weight) decreases by a factor of 1.3–1.9, with the proportion of grasses reaching 100%; the total abundance of invertebrates increases two-to threefold due to sucking phytophages, which account for up to 80% of the invertebrate community. The abundance of gnawing phytophages near the smelter is reduced, with some taxa entirely missing (e.g., mollusks and phalangiid harvestmen). Rearrangements in chortobiont community structure are attributable to changes in the physiological state of plants and in the species diversity and architecture of the herbaceous layer, with consequent modification of hydrothermal conditions in it, as well as by the direct toxic effect of heavy metals.     

Microscale Spatial Variation in Forest Litter Phytotoxicity

The spatial variation (within a 100 × 100 m plot) in the pollution of forest litter with heavy metals (Cu, Cd, Pb, and Zn), its acidity, and phytotoxicity (measured by the results of the root test using seedlings from a genetically homogeneous sample of common dandelion (Taraxacum officinale s.l.) have been estimated. Forest litter has been sampled in three zones differing in the toxic impact of long-term polymetal pollution by emissions from a copper-smelting plant emissions in the Middle Urals. The phytotoxicity variation is maximum in a moderately polluted plot, where both very high and very low pollution levels were observed, which determines a substantially nonlinear dose–effect relationship. The litter phytotoxicity is mainly accounted for by exchangeable forms of metals. Biological testing of samples from the most polluted plot has demonstrated marked antagonism between heavy metals and acidity.     

Industrial pollution reduces the effect of trees on forming the patterns of heavy metal concentration fields in forest litter

An analysis is made of the effect of large spruce and birch trees on the spatial pattern of the fields of heavy metal concentrations (Cu, Pb, Cd, Zn) and pH in the forest litter formed in tree stands exposed to long-term pollution with emissions from the copper smelter in Revda, Sverdlovsk oblast. The fields formed by trees growing in the background area have a regular spatial structure: the concentrations of elements decrease with increase in the distance from the tree trunk to the edge of canopy gap, with the position of sampling point relative to the trunk accounting for more than half of total variance. In polluted areas, the regular component of the field structure is very weakly expressed, and the main role is played by higher-order heterogeneity related to the mosaic pollution pattern on the scale of tens to hundreds of meters.     

Strategies of adaptation to heavy metal pollution in Deschampsia caespitosa and Lychnis flos-cuculi: Analysis based on dose-response relationship

The response to copper pollution was studied in the vegetative progeny of tufted hair grass (Deschampsia caespitosa (L.) Beauv.) and ragged robin (Lychnis flos-cuculi L.) plants growing together in chronically polluted areas around the Middle Ural Copper Smelter or in background areas. The root elongation test was used, with copper sulfate (0.006–0.51 mg Cu/L) being added directly to the nutrient medium. Using multimodel inference, dose-response curves were plotted for each of 85 maternal plants, and their parameters (effective Cu concentrations and curve slope in the linear segment) were evaluated. The pattern of transformation in dose dependence of root increment upon transition from background to impact populations proved to be basically different in the two species. The curves for L. flos-cuculi showed a parallel shift, with their shape remaining generally unchanged. In D. caespitosa, this transition was accompanied by a decrease in sensitivity to Cu, but tolerance to this metal was found to increase only at the highest concentration range. These results provide evidence for different strategies of adaptation to heavy metal pollution, which are discussed by comparing the physiological and ecological properties of the two species.     

Initial Stages of Recovery of Soil Macrofauna Communities after Reduction of Emissions from a Copper Smelter

Analysis of natural recovery of communities after reduction of industrial emissions is important for gaining an insight into their stability. However, there is obvious deficit in observations on the course of this recovery; in particular, no data on direct comparisons of the state of communities before and after reduction of emissions are available for soil macroinvertebrates. We have studied the structure of soil macrofauna communities at the level of supraspecific taxa in southern taiga spruce-fir forests in the region exposed to emissions from the Middle Ural Copper Smelter (MUCS; Revda, Sverdlovsk oblast). The data over three periods—high, reduced, and almost terminated emissions (1990–1991, 2004, and 2014–2016, respectively)—have been compared to test the hypothesis that the communities do not recover rapidly. The results partly confirm this hypothesis. On the one hand, the response of pedobionts to pollution at a qualitative level has remained basically unchanged: in each of the three periods, their total abundance (and that of the majority of groups) decreased abruptly as the MUCS was approached, with dominance shifting from saprophages to phyto- and zoophages. On the other hand, signs of recovery have appeared during the last period: the abundance of pedobionts has increased, and pollution-sensitive groups (earthworms, enchytraeids, and mollusks) have approached closer to the MUCS. This is most likely explained by decrease in the toxicity of metals due to normalization of soil pH. Rapid recolonization of defaunated territory may be accounted for by the presence in it of microsites with more favorable conditions, compared to the surrounding area, which allow low-mobile forms to survive beyond the boundaries of their main distribution area.

     

Analysis of Ecological Networks in Multicomponent Communities of Microorganisms: Possibilities,Limitations, and Potential Errors

Russian Journal of Ecology - Owing to the high resolving power and efficiency of DNA sequencing, researchers have discovered the extremely high diversity of bacterial, fungal, protist, and...     

Edge effects on pine stands in a large city

Manifestations of the edge effect on Scots pine (Pinus sylvestris L.) trees and stands were evaluated in natural southern taiga forests growing in a large industrial city (Yekaterinburg, Russia). For this purpose, 14 transects were laid out, each consisting of 6–10 circular 400-m² plots arranged in a line that extended for 140–260 m into the tree stand, perpendicular to its boundary. During transect surveys, 128 records were made of parameters characterizing the state of pine trees (height, diameter, defoliation level, needle age) and stands (density and timber volume). The boundaries differed in age, i.e., the time of formation (no more than 8 years and more than 20 years ago), and type (adjoining to motorways or wastelands). The edge effect manifested itself only near old boundaries and only for tree height (5 m lower near the boundary than deep in the forest) and for stand density and timber volume (25% lower), independently of the boundary type. Since the test parameters linearly increased with distance from the boundary, it was impossible to estimate the range of the edge effect.