The paper deals with the issues of determining the reference value of specific activity of cesium-137 of Chernobyl origin when applying the radiocesium method to assess the loss of gray forest soil in the areas of spread of the microrelief of paleocryogenic origin in the periglacial region of the upper Oka basin. Paleocryogenic microrelief is recognized in spring satellite imagery available on Google EarthTM. The necessity of choosing a reference plot for a specific field that differs in microrelief, exposure, and the nature of soil cultivation is substantiated. The authors analyze the data, which they obtained during the field research in 2016-2019, on three agricultural fields located on the arable slopes of the northern and southern exposure in the upper Oka basin within the Orel district of the Orel Region. Three experimental plots, selected in close proximity to one another, differed both in exposure and in the content of humus, labile phosphorus and radiocaesium in the arable layer. Layer-by-layer soil sampling at block elevations within the reference plots located on watershed surfaces, gamma-spectrometric and agrochemical analyzes of soil samples allowed us to draw a number of systematically important conclusions. The first is that the reference value of radiocaesium in the arable layer should be determined within block elevations on the watershed surface of the slope or on inter-valley micro-water divisions on the water-divide surface (if it is not possible to select a reference plot on the watershed surface). The second is that the dimensions of the reference plots are determined by the size of the block elevations (the sizes of blocks in the area under study are 10-20 m). The third is that the reference value of radiocaesium should be determined individually for each field that differs in exposure and in the nature of the soil treatment. In the experimental plot, the reference value of the specific activity of cesium-137 increases in the following order: a field located on the water-divide surface of the northern exposure slope, with a grain rotation, with regular fertilizing (130.5 Bq/kg) — a field located on the watershed surface of the eroded slope southern exposure (174.7 Bq/kg) — a field located on the water-divide surface of a less fertilized and less eroded slope of the northern exposure (180 Bq/kg). The results of the study show that the use of the radiocaesium method in periglacial areas requires testing a fundamentally new approach to its implementation: at the stage of determining the reference value of radiocaesium, it is necessary to take into account the polygonal-block structure of the watershed surfaces.
The paper presents some results of the study of natural-anthropogenic erosion network formation on open slope in the upper Oka basin (Orel region). On the example of 2014, it is shown that intensive precipitation (daily amount is comparable to the multi-year-averaged monthly amount), fell during the period when the field is not protected by vegetation (end of June and end of September, 2014), formed a breakup-furrow-based stream network. The satellite image collected on July 7, 2014 helped to detect this fact. Measurements of activity of the Chernobyl origin cesium-137 in the soil of thalwegs of the ancient ravines and modern streams (formed by the heavy rains of the summer and autumn of 2014 in breakup furrows), made it possible to estimate dependencies between cesium-137 activity and morphometric parameters of relief (catchment area and profile curvature) estimated by means of GIS for ancient ravines and modern streams. As a result of comparative analysis, it was found that the soil runoff on the Northern aspect slope in modern streams exceeds the runoff in the ancient ravines for more than 20 % (up to 50 %), while the values of catchment area are comparable. Soil runoff in modern streams can be predicted using the dependencies obtained for ancient ravines (applying corresponding raising factors) if June-September satellite imagery and precipitation monitoring data are available. Soil runoff in the tracks of agricultural machinery (with the 20 % evaluation error) can be estimated using equations obtained for inter-ravine surfaces. Where streams cross ancient ravines, calculation of soil washout must be performed by dependencies obtained for ancient ravines.
Arboretums are centers of introduction and study of woody plants’ ecological and biological characteristics, promising species identification for their subsequent introduction in landscape construction. The dendrological park has conducted studies of both wild and introduced species of woody plants, 117 species in total. The analysis of urban conditions stability and decorativeness of 117 woody plants’ species, including wild species, as well as systematic, biomorphological and chorologic analyses were performed. The article provides data on the degree of introduction and winter resistance of 96 trees and shrubs species. According to the results of the study, the list of the wood plants most successfully adapted to urbanized conditions for their further use in the cities of Central Russia considering their features in landscape design was composed.
The purpose of the study is to reveal the influence of European bison (Bison bonasus) on flora and vegetation change in Krasnikovsky forestry of “Orlovskoe Polesie” national park. In August-September of 2019, floristic and geobotanical studies of flora and vegetation were carried out at self-feeding stations, in the locations of salt licks, as well as in the bisons’ passage points in Krasnikovsky forestry of “Orlovskoe Polesie” national park. There were identified 142 species of vascular plants of 9 phytocenotic formations according to G. Zozulin’s classification: nemoral, birch forest, helobious grass, alder, boreal-willow, boreal forest, pine forest, meadow and anthropogenic. The number of phytocenotic groups and the percentage of species in each of them varied. A direct relationship was established between the time of self-feeding stations formation and the participation of non-forest species in the corresponding phytocenoses: the earlier self-feeding station was formed, the higher the participation percentage in the coen of non-forest species. When assessing geobotanical descriptions according to the Ramensky’s pasture digression ecological scale it was revealed that the greatest digression degree is observed in the locations of self-feeding stations: from a moderate influence of grazing (semi-pasture stage, 5 points) to a weak influence of grazing (hay stage, 4.5 points). In places adjacent to feeding self-feeding stations, or bisons’ passages, a weak influence of grazing was noted, a haying stage (3.7-4.0 points). In the places solonetzic soil locations, the influence of grazing does not affect (2 points) or there is a weak influence of grazing, haying stage (3-4 points).
Based on the authors’ data, the paper describes a methodology for assessing the spatial distribution of soil losses on the plowed slopes of the experimental site. The site is located in the basin of the Sukhaya Orlitsa River in the Orel District, Orel Region. The introduction of the principles of precision farming into land use practice requires a point estimate of soil losses, which is possible when using morphometric relief indicators. Geomorphometry methods in combination with GIS and the radiocaesium method made it possible to develop a method for calculating the specific activity of cesium-137 (as an indicator of soil losses) based on the morphometric parameters of the relief. The article presents the dependencies developed for depressions with a catchment area of ≤ 23,000 m2 and ≤ 50,000 m2. The development of a method for calculating soil losses in the elements of a depression complex on a plowed slope was carried out in two stages. At the first (field) stage, soil samples in the arable layer were taken in thalweg of depressions of different sizes. Sampling points were recorded during GPS survey. Gamma-spectrometric analysis of soil samples and their application to a digital elevation model (DEM) allowed to obtain a spatially distributed model of the specific activity of cesium-137 of Chernobyl origin on a scale of 1:10,000. To recognize the depressions, ultra-high resolution satellite images published in Google Earth were used. On the basis of the DEM, using the SAGA GIS tools, the authors built the fields of the collection area (calculated by the DEMON algorithm) and the profile curvature of the relief. The method was based on a system of dependences of the specific activity of cesium-137 on the collection area and the sign of the profile curvature. The specific activity of cesium-137 for inter-depression spaces was calculated using the equations developed for depressions with a collection area of up to 23,000 m2. To calculate soil losses, it was proposed to establish the reference value of cesium-137 individually for each of the three studied fields, which is due to the presence of the trend of Chernobyl fallout. In conditions of a polygonal block microrelief of paleocryogenic origin (which is widespread in the analyzed territory), the authors recommended determining the reference value of the specific activity of cesium-137 within block increases on the watershed surface of the plowed slopes. The trend was established on the results of the analysis of the layer-by-layer distribution of cesium-137 in depth in the thalweg of the depressions and in the balka, “receiving” overburdens from the fields under the study. Taking into account the results of the calculations, a map of the intensity of soil losses was constructed for the experimental site as of from 1986 to 2016.
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