Carbon accumulation in soils of forest and bog ecosystems of southern Valdai in the Holocene

Carbon stocks and accumulation rates in humus and peat horizons of the contiguous soil series of forest and bog ecosystems have been studied in the Central Forest State Biosphere Reserve, Tver Region. Upland soil types (soddy podzolic, brown, and white podzolic) have been compared to paludified (peat-enriched gley podzolic and peaty gley) and bog soils differing in trophic status, including those of upland, transitional, and lowland bogs. The results show that carbon stocks in mineral soils are many times smaller than in waterlogged soils and an order of magnitude smaller than in bog soils. Mineral and bog soils are characterized by similar rates of carbon accumulation averaged over the entire period of their existence. The highest rate of carbon accumulation has been noted for the soils of waterlogged habitats, although this process may be periodically disturbed by fires and other stress influences.     

Use of ganglioside-containing magnetic polyacrylamide sorbents for the immunoenzyme method of determining cholera enterotoxin

A variant of EIA techniques for the determination of cholera enterotoxin is proposed. This method is based on the selective sorption of the toxin on ganglioside-containing magnetic granules with its subsequent detection by means of immune serum and antispecific immunoperoxidase conjugate. The proposed method permits the detection of 0.052 +/- 0.02 ng of protein of the purified toxin.     

Soil properties under Norway spruce differ in spruce dominated and mixed broadleaf forests of the Southern Taiga

In natural forest, disturbance changes tree species composition which in turn affects soil properties. Two areas in the Central Forest State Biosphere Reserve, in the Russian Southern Taiga Zone, differed in the intensity of disturbance: Norway spruce was the dominant species at one site, while at the other spruce was mixed with broadleaves. The presence of broadleaves was due to large gaps in the canopy having been formed, which have triggered vegetation succession. At both sites, five plots were selected to evaluate how the presence of broadleaves influences the properties of the soils under spruce. Soil samples were taken close to spruce trees and the O, A and E horizons were analysed. A difference in the distribution of organic matter in the soil horizons was evident, with a higher concentration in the O and A horizons at the spruce dominated site, while a more homogeneous distribution was found under spruce at the site where broadleaves were abundant. The organic matter did not only differ in quantity, but also in quality as estimated by the C/N ratio, and therefore affected the CEC and element relative availability. No differences at the two sites were found for water-extractable and exchangeable elements, but the ratio between the exchangeable and the acid-extractable forms were different, suggesting a higher relative availability of the elements at the spruce dominated site, and thus potentially higher leaching. Both theoretical and empirical studies have suggested that podzolisation and accumulation of organic matter in the O horizon are related to stagnation of ecosystem processes and ecosystem decline. Our data suggest that the presence to windthrow sites and the inclusion of broadleaf species acts to slow or even reverse podzolisation even in spruce dominated sites.     

Some results of phenetic analysis of <Emphasis Type="Italic">Nicroforus vespillo</Emphasis> (Coleoptera,Silphidae) population from Kaluga city pine forest

The population phenetic structure was studied in the burying beetle Nicroforus vespillo (Linnaeus, 1761) from Kaluga city pine forest. Some possible phenes of N. vespillo were distinguished and frequencies of their occurrence studied. As a result, all the samples belonged to the same population. The phene pool of the population was characterized by indices of intrapopulation diversity and a share of rare morphs. Based on these characteristics, logarithmic trends were elaborated showing graphically the annual dynamics of the beetle population.     

Immunofluorescence method of detecting cholera enterotoxin

The quantitative immunofluorescent assay for the determination of cholera enterotoxin is proposed. The assay is based on the selective sorption of cholera enterotoxin by gangliosides incorporated into polyacrylamide granules. The preliminary treatment of gangliosides with neuraminidase enhances the sensitivity of this assay. The assay permits the detection of cholerigen in an amount of 20 ng.