On causes of gigantism in herbaceous plants

Landscape-geochemical features providing for manifestation of gigantism in herbaceous plants have been revealed in natural habitats in the south of Sakhalin and Kunashir islands. Tall herb assemblages have proved to be associated with geochemical landscapes characterized by reducing (gley or hydrogen sulfide) conditions and increased contents of petroleum hydrocarbons and some trace elements (total and movable forms). A hypothesis is put forward that gigantism in herbaceous plants is manifested in zones of active faults, which serve as a kind of conduits supplying endogenous heat, matter, and water to the root systems.     

Chemical pollution: Transfer of chemical elements to the aboverground phytomass of herbaceous plants

Changes in the species composition and a decrease in species diversity and total plant biomass along the gradient of soil pollution with heavy metals have been shown. Data on the concentrations of chemical elements (Zn, Cu, Cd, Pb, Co, Ni, Mn, Cr, and Fe) in the aboveground organs of herbaceous plants and the biomass of each species make it possible to estimate the role of higher producers in the incorporation of chemical elements into biogenic cycles in background zones and under conditions of chemical pollution. Plants of the composite family (Asteraceae) play the main role in accumulation of chemical elements. The results obtained indicate that natural ecosystems have mechanisms limiting excessive accumulation of chemical elements into the aboveground plant biomass.     

Natural and artificial radioactivity determination of some medicinal plants

Several medicinal plants used in Italy were analysed to determine natural and artificial radioactivity in those parts (leaves, fruits, seeds, roots, peduncles, flowers, barks, berries, thallus) used generally as remedies. The radionuclides were determined by alpha (²³⁸U, ²¹⁰Po) and gamma (²¹⁴Pb-Bi, ²¹⁰Pb, ⁴⁰K and ¹³⁷Cs) spectrometry. ²³⁸U ranged between <0.1 and 7.32 Bq kg_dry⁻¹; ²¹⁰Po between <0.1 and 30.3 Bq kg_dry⁻¹; ²¹⁴Pb-²¹⁴Bi between <0.3 and 16.6 Bq kg_dry⁻¹; ²¹⁰Pb between <3 and 58.3 Bq kg_dry⁻¹; ⁴⁰K between 66.2 and 3582.0 Bq kg_dry⁻¹; ¹³⁷Cs between <0.3 and 10.7 Bq kg_dry⁻¹. The percentage of ²¹⁰Po extraction in infusion and decoction was also determined; the arithmetical mean value of percentage of ²¹⁰Po extraction resulted 20.7 ± 7.5.     

Prevalence and intensity of mycorrhiza formation in herbaceous plants with different types of ecological strategies in the Middle Urals

The prevalence of arbuscular mycorrhizas and abundance of mycorrhizal fungi in the roots of herbaceous plants with different types of Grime-Ramenskii’s ecological strategies (competitors, ruderals, and stress tolerators) have been studied in the Middle Urals. The closest association with arbuscular fungi has been observed in species with a competitive strategy. Compared to them, stress-tolerant species are characterized by lower abundance of mycorrhizal fungal hyphae in the root system, while ruderal plants include a relatively large proportion of nonmycotrophic species showing no interaction with arbuscular fungi.     

Adaptive features of leaf structure in plants of different ecological groups

It is well known that the structure of leaves plays an important role in adaptation, but there are still no accurate structural criteria to indicate ecological characteristics of the species. We have studied parameters of leaves in 100 herbaceous plant species growing in the southern taiga subzone that belong to different ecological groups in relation to irradiance and moisture supply. The results show that leaf area, thickness, and anatomical type are less correlated with ecological characteristics of the species than structural parameters of photosynthetic tissues. In the series shade-loving mesophytes—light-loving hygromesophytes—mesophytes—xeromesophytes—mesoxerophytes, the concentration of cells and chloroplasts in the leaf gradually increases by a factor of up to 7–10, their size decreases two-to threefold, and the ratio of mesophyll surface area to leaf surface area increases fourto fivefold. It is concluded that characteristics of mesophyll are of adaptive significance. A system of characters is proposed for identification of ecological groups of plants growing in the boreal zone.     

Morphological and biological features of plants related to their adaptation to coastal habitats

The results of studies on the biomorphological features of 22 plant species growing on the southern coast of the Russian Far East provide evidence for the diversity of pathways of their adaptation to stressful habitat conditions. An analysis of the anatomical and mesostructural characteristics of their leaves has revealed representatives of euhalophytes, crinohalophytes, and glycohalophytes among these plants. Adaptation is achieved by means of halomorphosis, haloxerophytism, and development of some heliophilic features accounted for by species-specific manifestations of succulence, the presence of salt excreting trichomes, and thick pubescence. The similarity of these adaptations to those of desert plants is discussed. Along with plants characterized by a high germination rate, species that counterbalance a low efficiency of seed reproduction by active vegetative propagation have also successfully established themselves on the coast. Adaptation to coastal habitats is also achieved due to the diversity of life forms characterized mainly by tap root systems with laterally extending branch roots, creeping shoots, and a high vegetative mobility.     

Natural radioactivity in refractory manufacturing plants and exposure of workers to ionising radiation

This paper shows the results of a survey carried out at some refractory manufacturing plants. During the first part of the survey, the concentration of natural radioactivity in raw materials and end-products, coming from four plants, was assessed. Several raw materials and, as a consequence, some end-products as well have shown activity concentrations exceeding a few hundreds of Bq kg⁻¹ of ²³⁸U and ²³²Th. In some important raw materials, such as bauxite and corundums, a remarkable radioactive disequilibrium was observed; this is probably due to the high temperature processes undergone by these materials. The second part of the survey focussed on the measurements of ambient equivalent dose rates, airborne dust concentrations and radon indoor. On the basis of results obtained, the effective dose for the standard worker was estimated. Two different types of refractory plants were investigated. Effective doses for both plants were lower than 1 mSv y⁻¹.     

Migration and biological effect of natural heavy radionuclides on plants

A complex radioecological study of technogenic landscapes of southern Yakutia showed that the main factor responsible for their contamination with uranium and radium is radionuclide dispersal by air with products of rock weathering. Coefficients of biological absorption by plants decrease with an increase in the contamination level, which is explained by the fact that strongly fixed forms of uranium and radium prevail in the contaminated areas. In addition, the root barrier plays an important role. Radiation load is mainly determined by background gamma-radiation. The contribution of internal irradiation accounted for by incorporated radionuclides does not exceed 16% and decreases with an increase in the level of soil contamination. Manchurian alder seeds produced under conditions of enhanced background radiation are more viable than those from the control area. It is shown that seed generations of plants growing under conditions of chronic irradiation are highly resistant to the radiation factor.     

Dynamics of herbaceous layer structure around the nests of <Emphasis Type="Italic">Formica aquilonia</Emphasis> Yarr. at initial stages of their formation

The time course of changes in characteristics of herbaceous vegetation around Formica aquilonia Yarr. ant nests formed from artificially relocated fragments of original families was studied over 6 years. At the initial stage of nest formation, species richness and diversity of the herbaceous layer decreased, and its taxonomic, spatial, phytocenotic, and ecological structure changed. Trivialization of vegetation around anthills was observed. The proportion of zoochorous and anemophilous plants with narrow or strongly dissected leaves increased in the developing myrmecotopic assemblages.     

Intrapopulation Differentiation by the Rates of Rosette Growth and Individual Plant Development in Narrow-Leaved Hawk’s Beard (<Emphasis Type="Italic">Crepis tectorum</Emphasis> L.): Aftereffects of Long-Term Stress

Aftereffects of exposure to long-term chemical pollution with fluorine and sulfur compounds on intrapopulation differentiation of the rates of growth and development has been studied on Crepis tectorum L. progenies obtained from seeds collected in a pollution gradient and grown in a greenhouse under uniform ecological conditions. The results have shown that long-term stress (exposure to toxic gaseous pollutants) leads to significant changes in the intrapopulation structure, which are manifested in an increase in the proportion of plants with a low rate of development, a low relative rate of the linear growth of metameres (leaves), but a higher relative rate of their formation.__________Translated from Ekologiya, No. 4, 2005, pp. 243–251.Original Russian Text Copyright © 2005 by Trubina.     

Ecological Segregation of Bustards (Otididae) in the North of the Lower Volga Region: Evolutionary and Adaptive Aspects

Based on the concept of an ecological niche, the processes of segregation in the Lower Volga populations of great and little bustards (Otis tarda L. and Tetrax tetrax L). have been studied in the evolutionary and adaptive aspects. The results have shown that segregation of the ecological niches of the two species occurs mainly on a trophic basis, when bird specialization in the use of food resources provides the possibility of changing the nesting biotopes. Some trophic adaptations are temporary and do not modify a species-specific stereotype, whereas other adaptations lead to the development of new forms of behavior and their evolutionary stabilization. Spatial characteristics (biotopic preference, nest location, etc.) complement the identified hierarchical series of parameters characterizing the ecological niches of the species studied. In the Transvolga region of Saratov oblast, the total sizes of great and little bustard populations in the breeding season reach approximately 4100 and 5900 birds, respectively.     

Distribution of herbaceous plants around nests of <Emphasis Type="Italic">Formica aquilonia</Emphasis> Yarr. in a fragmented forest area

Topical connections between F. aquilonia ants and herbaceous plants in a fragmented forest area have been analyzed. The species composition of the group of herbaceous plants changing their occurrence frequency in response to the presence of F. aquilonia nests has been determined. Ecological and phytocenotic parameters of herbaceous plants contributing to the development of the myrmecotopic assemblage are described. Signs of meadowfication and synanthropization of the herbaceous layer around ant nests have been observed.     

Distribution of plants differing in attitude toward thermal conditions in communities of the timberline ecotone on Mount Iremel’, the Southern Urals

Specific features in the distribution of plant species differing in their attitude toward thermal conditions have been studied in communities of the present-day timberline ecotone on Mount Iremel’ in the Southern Urals. It has been shown that the distribution of such species is characterized by significant spatial nonuniformity. Elevation above sea level, local conditions in habitats located at the same altitudinal level, and specific features of mountain slopes account for 13–84, 5–30, and 0.4–14% of the total variance of test parameters, respectively. The abundance of plants changes nonlinearly along the altitudinal gradient, whereas changes in the species diversity of different plant groups have an almost linear pattern. Marked differences between plant communities with respect to the proportions of species differently responding to changes in thermal conditions have been revealed on all slopes in the upper part of the timberline ecotone, upon transition from the slopes proper to the plateau-like areas of intermontane depressions.     

Concentrations of (137)Cs in summer pasture plants that reindeer feed on in the reindeer management area of Finland

Samples of summer pasture plants that reindeer feed on were collected in order to study ¹³⁷Cs concentrations in different plant species and in species nested in certain site types, and to study the regional distribution of ¹³⁷Cs in the Finnish reindeer management area. Plant species were categorized by the site types of mineral soil forest (xeric heath forest and mesic heath forest) and peatland. A third category called ’other plant species’ included plants with various site types, poorly determined species and species with poor statistics. The ¹³⁷Cs concentrations in different site types differed significantly. The mean ¹³⁷Cs concentrations of the whole reindeer management area in the xeric heath forest plant species was 44 ± 27 Bq/kg dw, in the mesic heath forest plant species 75 ± 59 Bq/kg dw and in the peatland plant species 219 ± 150 Bq/kg dw. The peatland species uptake ¹³⁷Cs more efficiently than plant species of mineral soil forests. A particularly efficient collector of ¹³⁷Cs was Trichophorum sp. It is suggested that Trichophorum sp. could be used as an indicator species for reindeer summer fodder plants. The highest concentrations of ¹³⁷Cs were found in Southern Lapland and the lowest in Northern Lapland. Today, the concentrations of ¹³⁷Cs in summer pasture plants that reindeer feed on in Finland are at such a level that there is no need to avoid any plant species. In the case of future nuclear fallout, reindeer grazing in peatlands would increase concentrations of ¹³⁷Cs in reindeer meat.     

The Use of Natural Taraxacum officinale Wigg. Populations for Assessing the State of Technogenically Disturbed Areas

Russian Journal of Ecology -     

Bioaccumulation of Ra by plants growing in fresh water ecosystem around the uranium industry at Jaduguda, India

A field study has been conducted to evaluate the ²²⁶Ra bioaccumulation among aquatic plants growing in the stream/river adjoining the uranium mining and ore-processing complex at Jaduguda, India. Two types of plant group have been investigated namely free floating algal species submerged into water and plants rooted in stream & riverbed. The highest ²²⁶Ra activity concentration (9850 Bq kg⁻¹) was found in filamentous algae growing in the residual water of tailings pond. The concentration ratios of ²²⁶Ra in filamentous algae (activity concentration of ²²⁶Ra in plant Bq kg⁻¹ fresh weight/activity concentration of ²²⁶Ra in water Bq l⁻¹) widely varied i.e. from 1.1 × 10³ to 8.6 × 10⁴. Other aquatic plants were also showing wide variability in the ²²⁶Ra activity concentration. The ln-transformed filamentous algae ²²⁶Ra activity concentration was significantly correlated with that of ln-transformed water concentration (r = 0.89, p < 0.001). There was no correlation between the activity concentrations of ²²⁶Ra in stream/riverbed rooted plants and the substrate. For this group, correlation between ²²⁶Ra activity concentration and Mn, Fe, Cu concentration in plants were statistically significant.     

中国生物多样性保护适应气候变化的对策

基于气候变化对生物多样性影响的总结分析,初步提出了我国生物多样性保护适应气候变化的对策。气候变化对生物物候、分布、迁移活动、群落结构、栖息地质量、生态系统和景观多样性都产生了一定影响,未来将产生更深刻的影响。我国生物多样性保护适应气候变化需要从物种有效保护、自然保护区规划与管理、灾害防御等方面进行。