Yulia Lvovna Meshalkina
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Spatial variability of the granulometric composition within arable fi eld on soddy-podzolic soilMoscow University Bulletin. Series 17. Soil science. p.61-67Vera P. Samsonova Yulia. L. Meshalkina Marina I. Kondrashkina Svetlana Ev. Dyadkina Anastasia V. Zotkinaread more307
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The spatial variability of the content of granulometric fraction d > 0,25 mm in the arable layer of soddy-podzolic cultivated soil on an area of 18 hectares was studied. The soil formed in the loess-like loam, underlain by moraine deposits. Samples were taken from the upper (0–10 cm) and lower parts of the arable layer (10–20 cm) following a random-stratified sampling scheme. The total number of samples was 350 cores. The average fraction content was about 22%, the coefficient of variation was 39–41%, the distributions were approximated by a logarithmically normal distribution. The Spearman correlation coefficient between values at different depths equaled to 0,87. The spatial distribution cartograms were constructed by the ordinary kriging method using a spherical variogram model. It is shown that preliminary censoring of high sample values (quantile 0,95) gives better results when constructing a cartogram than removing a linear spatial trend and logarithm of the original data. Spatial structures with reduced and increased values were found on the site, the average linear sizes of which was about 100 m. Presumably, they were associated with the heterogeneity of soil-forming material.Keywords: censorship; ordinary kriging; cartogram; loess-like loams; Moscow region; coarse and medium sand; gravel
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The number of repetitions during of the soil organic carbon content monitoring in the forest revisitedMoscow University Bulletin. Series 17. Soil science. 2024. 1. p.16-23read more106
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Using the example of data from the article by E.A. Dmitriev et al., the estimation of the required number of soil samples to assess the SOC content in the forest biogeocenosis during monitoring studies is considered. Primary data on SOC content were obtained in the spruce forest at 166 points in layers 0–10, 10–20, and 20–30 cm after removal of the litter. The sampling was carried out at the nodes of a regular grid of equilateral triangles with 1 m side within a regular hexagon with a side of 7 m. The SOC content was determined by the Tyurin method. The original article presents statistics for three zones — near-stem, under-crown and inter-crown space. Spatial variation in all zones and at all depths is high, the coefficients of variation are about 50%. It is shown that the number of replicates required for estimating the average SOC content at a 95% confidence level in the 0–10 cm layer is hundreds of samples and decreases to tens of samples in the 20–30 cm layer. Since the number of repetitions for testing hypotheses about the equality of means depends not only on the confidence level, but also on the power of the criterion used, the required number of repetitions increases several times. Sampling with samples taken from the entire vertical layer of 0–30 cm and forming mixed samples from them reduces the number of required repetitions, however, careful observance of sample preparation, including primary mixing of samples, is required.Keywords: carbon stocks; coefficient of variation; estimation of the mean value; contrast of means; significance level; power analyses; sample size; mixed samples
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Coniferous leaf-bearing forest biomass assessment by the example of the educational and experimental soil and ecological center of Lomonosov Moscow State University «Chashnikovo»Moscow University Bulletin. Series 17. Soil science. 2024. 2. p.37-45read more32
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The aim of the work was to assess the contribution of the following components – biomass and mortmass of tree stands, undergrowth, living ground cover, and forest litter — to the total organic matter’s pool of plant community. The object of the study was a territory of coniferous-deciduous forest located in Solnechnogorsk City District of the Moscow region, in which five permanent sample trial plots of 50×50 m were allocated. The greatest contribution to the total organic matter mass of studied plant communities was made by forest stand perennial parts (up to 87%) and forest stand mortmass (up to 14%), and phytomass of deciduous trees in stand containing 32 to 98%, which was connected with incompleteness of forest restoration succession process. The contribution of forest litter was no more than 3%; litter deposit was low (0,18–1,21 kg×m-2), which is not typical for spruce forests, as is the fact that all litter is of the destructive type. Living ground cover in terms of floristic composition and ecological-coenotic structure was typical for the subzone of coniferous-deciduous forests; its contribution to the overall productivity of forest biogeocenosis was insignificant. The spatial intrabiogeocenotic structure of litter reserves and living ground cover biomass distribution was disturbed compared to typical spruce forests due to the high proportion of deciduous species in the forest stand. Deciduous species inclusion in the tree tier, typical of the final stage of formation of a secondary coniferous forest during succession, caused a slight increase in the intensity of the biological cycle, which was indicated in this case by a decrease in the supply of litter and a simplification of their structure. Since the biomass and mortmass of tree stand make the greatest contribution to the sequestration of carbon by forest biogeocenoses, it is these components that require the most detailed assessment during monitoring observations, the purpose of which is to assess the carbon reserves of terrestrial ecosystems.
Keywords: species composition; mortmass; ground cover; litter; permanent sample plots
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