Home – Home – Jornals – Contemporary Problems of Ecology 2013 number 5

Information about the effect of wetting regime on the composition of the flora of the Verkhoyansk Ridge (Yakutia) is presented. The regularities of changes in ecomorph structure in connection with latitudinal zoning and vertical belt sequence of the mountain system under consideration are analyzed.

Results of the investigation of postfire succession dynamics in light-coniferous – small-leaved forests in the Prienisey part of the Eastern Sayan on the landscape-ecological basis are presented. A generalizing scheme of the directions and rates of succession interchanges taking into account the pyrogenic factor was built and analyzed.

Data of the experimental investigation of postfire digression of the subtaiga – forest-steppe pine forests in the South-Western Pribaikalia are analyzed. It was established that the surface fire of forest floor – humus type are the major destructive factor in the dynamics of pine forests. The action of the surface fire is accompanied by tree dryout, while the vitality of the trees that survived in fire depends on the severity of fire damage. Characterization of the lower plant storeys and its dynamics under the effect of middle-intensity fire events are presented. A negative effect of surface fire on the changes of the stand, qualitative fractional composition of organogenic soil horizons and their chemical composition was demonstrated.

The phytocenotic role of separate Gmelin larch trees that survived on burns after fire was shown for the conditions of cryolitozone of Middle Siberia. Depending on the vital state of the trees, the boundaries of their effect on the recovery of species composition of the lower storeys of phytocenoses and the formation of a new generation of tree stand were determined.

Ecological structure of flora burnt depends on climatic conditions and geographic location. The secondary post-fire succession in lowland pine forests occurs rather rapidly, and after ten years the burns are at the stage of the formation of communities of patient plants. Pyrophyte plants become important in the formation of vegetation in burns. Formation of zonal vegetation types does not occur in ten years. A reduction of periods between fires leads to the fact that plant communities in flat pine forests are under constant influence of the pyrogenic factor.

Pyrogenic changes of microelement content in soil and plants of the pine forests of West Transbaikalia (Republic of Buryatia) were studied. It was established that surface fires under the studied conditions cause changes of soil properties, insignificant increase in the concentrations of Mn, Zn, Cu, Pb in the upper layers of soil (0–40 cm) and Mn, Zn, Pb in plants. It was revealed that the ratio Fe : Mn in soil gets narrower. Investigations show that the pyrogenic change of vegetation and soil properties, in particular elemental composition, is observed during several years after the fire.

The data on the variability of the structure of plant communities formed under the conditions of the steppe extrazonality of the Barguzin basin (North-Western Pribaikalye) are represented. Geobotanic and soil profiles for one of the most significant study areas were made. The structure of contact communities of the light-coniferous taiga and extrazonal steppe was revealed. The edaphic conditions and location of plant communities reflected the direction of vegetation cover developing in this part of Pribaikalia.

Soil samples from natural forests and adjacent farmland were analyzed to investigate the dynamics of soil organic matter of red soil in Southern, China. Based on the δ¹³C values and the content of soil organic matter, the data indicated that the turnover of soil organic matter under the virgin forest was slower than that under cultivation. Soil organic matter is fresh in coarse sand and oldest in fine silt and clay. Also, the soil light fraction contained the younger organic matter than soil heavy fraction and bulk soil. Deforestation has accelerated the decomposition rate of soil organic matter and reduced the proportion of active components in SOM and thus soil fertility.

Soil seed bank is an important component of ecosystem resilience and represents a stock of regeneration potential in many plant assemblages. Soil seed banks can be used to predict the composition of new plant recruitment. Species overcome periods of unfavorable weather conditions by building up a large seed bank. With this strategy, the species diversity is preserved and information on their dynamics and structure is retained. The research on soil seed bank has received wide interest because of its important role in plantation renovation and restoration, biological diversity preservation, vegetation succession and diffusion processes and other aspects. This paper reviews the relationship between soil seed bank and disturbance, geographic factor, vegetation and seed size and is aimed at providing some useful reference for future research.

The hygroscopic properties of forest floor in coniferous (Larix sibirica Ledeb., Pinus sylvestris L.) and deciduous (Populus tremula L., Betula fruticosa Pall.) plantations were studied using the isotherms of water vapor sorption and methods of thermal analysis (TG, DSC). Sub-horizons OL and OF in larch and pine plantations had the larger monolayer adsorption capacity. The forest floor in larch plantation was characterized by the highest hydrophilicity. Results of DSC indicated that hygroscopic water had higher binding with the substance of sub-horizon OL in coniferous and sub-horizon OH in deciduous plantations. The forest floor in coniferous plantations was characterized by higher store of hygroscopic water than in deciduous ones.

Investigation of the enzymatic activity of modern and lower gorizont of soils of the islands and the near-bench floodplain of the Lobanovskaya branch at the right bank of the Selenga delta is described. Ecological conditions determining its differences at the regions under study are conditions. Evaluation of the activity of enzymes in the soils of the right bank part of the delta in comparison with the regions of the left-bank part differing in the landscape ecological parameters is presented.

Results of laboratory modeling of the remediation of waste product containing oil products (652 g/kg) and natural radionuclides (²²⁶Ra, ²³²Th и ⁴⁰K) by means of landfarming, biostimulation and bioaugmentation are presented. It is established that landfarming and biostimulation provide a decrease in oil product content and in the phytotoxicity of the waste product; landfarming is a more rapid process.

Phytomonitoring of atmospheric pollution was performed using Scotch pine as a highly sensitive bioindicator. Pine needle samples were collected in reference sites along the 320 km Sayansk-Irkutsk-Listvyanka transect passing through the major industrial centers of Baikal region and stretching to the shores of Lake Baikal. The concentrations of inorganic pollutants such as sulfur, fluorides, heavy metals etc. in needles were determined. The highest level of atmospheric pollution was detected at the territories of the Angarskiy, Irkutskiy, Usolskiy, Shelekhovskiy industrial centers, lower pollution is observed within the Sayan and Cheremkhovo industrial centers. The data show that the majority of pollutants reach the Baikal shore.

The anatomic-morphological indicators of the needles of Picea obovata Ledeb. under the effect of emissions from the industrial zone of Kemerovo were investigated. Some changes of the negative nature were detected: a reduction of length, area and the surface of pine needles, the thickness of the inner lining and epidermis, an increase in the asymmetry of the central conducting beam, a reduction of the number of pitch channels. Some changes of the adaptive nature were also detected: an increase in the thickness of epidermis and endodermis, an increase in the area of pitch channels and the central cylinder. The significant correlation of the complex index of atmospheric pollution with the anatomic-morphological characteristics of pine needles was revealed. This confirms the fact of the substantive effect of emissions from the industrial zone of Kemerovo on the anatomical structure of pine needles of Picea obovata Ledeb.

Evaluation of urban soil for Kirov as example was carried out by means of chemical analysis and biotesting. Total content and the concentrations of mobile forms of heavy metals (Zn, Cu, Cd, Ni, Fe, Pb), pH of water and salt extracts, humus content were determined in different regions of the Kirov city. On the basis of the total index of tecnogenic pollution (Z_c), urban soil is characterized by the low level of pollution. Test objects of different trophic groups were used for biotesting: Daphnia magna Straus , Paramecium caudatum, Escherichia coli. Results of the comparative analysis of the sensitivity of different biotesting methods are presented.

The six litter types, such as heavily decomposed, middle decomposed, rhizome-like (coarse decomposed), turfy, peaty and turf, were determined on the gradient of large grass-dead soil cover-sphagnum in the bog birch forest. Specificity of their biochemical transformation depends on the amount of gumic acid accumulation, mainly of the first fraction (GA-1), at the background of relatively uniform rate of the formation of fulvic acids. The intensity of GA-1 formation is closely positively connected with the biological activity of substratum, judging from the C/N ratio. However, unclear distinctions between these indices of forestry-morphological litter types limit their diagnostic reliability. Grouped biochemical litter categories – mild (heavilyand middle decomposed), transitional (rhizome-like, turfy, peaty) and coarse (mossy) are significantly discriminated by the C/N ratio – 20, 30, 40, as well as by the content of GA-1 – 14, 10, 6 %, respectively.

Incidence and intensity of bark stripping of trees by ungulates was investigated at no bamboo (Fargesia nitida (Mitford) Keng f. ex Yi) (B–) site and understory bamboo dominant (B+) site of a subalpine Abies faxoniana forest, southwest China. The percentage of damaged trees in B– site was higher than in B+ site. Bark stripping obviously occurred more frequently on Abies faxonian а Rehder & E. H. Wilson compared to other tree species. Appearance of stripped bark and dead stems of the trees in different size-classes of A. faxoniana strongly depended on the density of dwarf bamboo at the site, and also on the size and bark structure of the trees, with highest damage rates occurring on the smaller DBH classes (10–40 cm) in B– site. The bark stripping intensity of A. faxonian а decreased significantly with higher density and coverage of F. nitida around damaged trees. Therefore, there is an indirect negative effect of the distribution of dwarf bamboo, F. nitida , on bark stripping of tree species. We suggest the indirect effects of dwarf bamboo species should be taken into account while considering the succession and regeneration of natural forests.