Архив метки: Caspian lowland

HARMONIZATION OF THE RESULTS OF SOIL SALINITY CHEMICAL STUDY

Arid Ecosystems

UDC 631.4

Prokopyeva K.O., Konyushkova M.V. HARMONIZATION OF THE RESULTS OF SOIL SALINITY CHEMICAL STUDY // Arid Ecosystems. 2023. Vol. 29. № 3 (96). P. 24-35. | PDF

Soil salinity is one of the main ecological factors that limits the growth and productivity of many plants. Its assessment in different countries is carried out by different methods. In Russia and some other countries, soil salinity is assessed using water extracts. Internationally, the method of electric conductivity of soil paste extracts is widely used. These methods are labor-consuming, and, therefore, the reduced methods are used to assess soil salinity for mass analysis. Thus, in Russia, salt surveys are often evaluated by the leading toxic ion (chlorine or sodium). In a number of foreign countries assessment is given by electrical conductivity at various ratios of soil to water (1: 1; 1: 2.5; 1: 5; 1: 10). In this study, comparisons of different methods for substantiation of possibility to use electrical conductivity measurement in 1: 5 suspension were carried out. The following methods were compared: 1 – method of determination of specific electric conductivity in water suspension (1: 5); 2 – method of determination of pNa and pCl measured in water suspension (1: 5) using ion-selective electrodes; 3 – determination of sodium in water suspension (1: 5) by atomic absorption spectrometry. Salinity was evaluated in samples of light clayey soils of the dry steppe zone of mainly chloride-sodium salinity type. The results showed that when determining the activity of ions, the greatest correlation was observed between measurements of specific conductivity (conductometer) and sodium activity (ion-selective electrodes). A sufficiently close correlation between specific conductivity and the content of sodium ions in the water extract was revealed and the function of recalculation of these indicators was obtained: ЕС1: 5 = 0.213Na1: 5 + 0.17 (with intercept); ЕС1: 5 = 0.23Na1: 5 (without intercept). For evaluation of salinity degree according to specific conductivity index (1: 5) the following criteria are suggested: 0-0.4 dS/m (non-saline), 0.4-0.6 dS/m (slightly saline), 0.6-1 dS/m (medium saline), 1-1.9 dS/m (strongly saline), > 1.9 dS/m (very strongly saline). When comparing different gradations of soil salinity with the help of contingency tables using chi-square and kappa index, the presence of statistically significant contingency was revealed, which allows us to use different methods of soil analysis to assess the degree of salinity.

Keywords: salinity, soil analysis, electrical conductivity, ion selective electrodes (ISE), sodium, Caspian Lowland.

Financing. The work was supported by the funds for the Eurasian Center for Food Security of Lomonosov Moscow State University (Decree No. 1736-r, dated 26/06/2021).

DOI: 10.24412/1993-3916-2023-3-24-35

EDN: WCVAFO

THE USE OF MULTI-TEMPORAL HIGH-RESOLUTION SATELLITE IMAGES TO SOIL SALINITY ASSESSMENT IN THE SOLONETZIC COMPLEX (REPUBLIC OF KALMYKIA)

Arid Ecosystems

UDC 631.4

Prokopyeva K.O. THE USE OF MULTI-TEMPORAL HIGH-RESOLUTION SATELLITE IMAGES TO SOIL SALINITY ASSESSMENT IN THE SOLONETZIC COMPLEX (REPUBLIC OF KALMYKIA) // Arid Ecosystems. 2022. Vol. 28. № 4 (93). P. 61-74. | PDF

Remote assessment of soil salinity of natural solonetzic complexes, which are characterized by subsurface soil salinity, is a challenging task. Nevertheless, research in this area is promising, as salinity is a striking limiting factor affecting vegetation growth, and thus manifests itself on the spectral characteristics of the land surface. In this paper, an analysis of multi-temporal high-resolution satellite images compared with detailed ground data on soil salinity was carried out using the principal component method and multiple linear regression. Images from QuickBird (2007) and SuperView-1 (2021) satellites were used as remote sensing data with a spatial resolution of 2 m. Salinity was estimated by specific electrical conductivity (EC) in a water suspension of 1:5. Ground surveys were carried out in 2011 and 2021. It was found out that there were no significant changes in soil salinity in the key area during the 10-year period, but there were changes in vegetation conditions, which are reflected in the NDVI vegetation index maps. The principal components were calculated from multi-temporal high-resolution satellite images and it was concluded that the first three components explain almost 97% of the total image variability. Models based on multiple linear regression analysis describe well the soil salinity (R2 of the model is 0.68, 0.77, 0.83 for layers 0-30, 0-50, 0-100 cm, respectively). The constructed models based on remote sensing data have shown good agreement when tested with the control sample (R2 between predicted and measured EC values is 0.70, 0.87, 0.83 for layers 0-30, 0-50, 0-100 cm, respectively). The proposed models will be useful for estimation of salinity of soils of solonetzic complex of dry steppe from high resolution satellite images.

Keywords: QuickBird, SuperView-1, assessment of soil salinity, solonetzic complexes, Principal Components Analysis (PCA), NDVI, Caspian Lowland.

Acknowledgement. The author expresses gratitude for the help in the work of M.V. Konyushkova, I.P. Minkeev, A.F. Novikova, M.B. Shadrina, S.S. Ulanova, I.N. Semenkov, A.A. Kontoboitseva, Isinufen, N.M. Tserenov, U.Y. Ulumdjiev.

DOI: 10.24412/1993-3916-2022-4-61-74

EDN: PTOYDP

ECOLOGICAL-PHYTOCENOTIC CLASSIFICATION AND CHARACTERISTICS OF THE HALOCNEMETA STROBILACEI FORMATION ON THE CASPIAN LOWLAND

Arid Ecosystems

UDC 581.5.526.523

Goryaev I.A., Safronova I.N. ECOLOGICAL-PHYTOCENOTIC CLASSIFICATION AND CHARACTERISTICS OF THE HALOCNEMETA STROBILACEI FORMATION ON THE CASPIAN LOWLAND // Arid Ecosystems. 2022. Vol. 28. № 4 (93). P. 83-90. | PDF

Halocnemeta strobilacei is represented by 4 classes of associations and 14 associations on the Caspian lowland within European Russia.Сommunities of Halocnemeta strobilacei are common in desert and steppe zones, in which they differ in species composition and occupied area.

The most common are the cenoses of Halocnemeta strobilacei pura association class. Communities of two classes of associations are characteristic: Halocnemeta strobilacei halosuffruticulosa and Halocnemeta strobilacei annuae. It is rare to find communities of another class of associations Halocnemetum strobilacei graminosa. Monodominant communities of Halocnemeta strobilacei are confined to soils with a high content of chlorine ions (Cl—). In soils under bidominant cenoses, in addition to chlorine ions (Cl—), natrium ions (Na+) and sulfate ions (SO42-) have a high content.

Keywords: communities, Halocnemeta strobilacei, dwarf semishrubs, annuals, classification scheme, Caspian lowland.

Funding.The work was carried out on the planned topic of the Laboratory of General Geobotany of the BIN RAS «Vegetation of European Russia and Northern Asia: diversity, dynamics, principles of organization» No. 121032500047-1 and under the research agreement No. 1/71 dated 30.04.2021 of the BIN RAS with the World Wildlife Fund «Assessment of saiga habitats of the Northwestern Caspian Sea».

DOI: 10.24412/1993-3916-2022-4-83-90

EDN: KHCHJE

CHANGES IN ECOSYSTEM COMPONENTS OF REclaimed SOLONETZES IN THE PRIERGENINSKAYA PLAIN DURING THE GROWING PERIOD (REPUBLIC OF KALMYKIA)

Arid Ecosystems

UDC 581.5

Novikova N.M., Konyushkova M.V., Ulanova S.S., Volkova N.A., Chemidov M.M., Bembeeva O.G., Fedorova N.L. CHANGES IN ECOSYSTEM COMPONENTS OF RECLAIMED SOLONETZES IN THE PRIERGENINSKAYA PLAIN DURING THE GROWING PERIOD (REPUBLIC OF KALMYKIA) // Arid ecosystems. 2022. V.28. № 3 (92). P. 79-93. | PDF

During the growing season of 2021, in early May, late June and early September, observations were carried out on the functioning of the main components of ecosystems recovering after reclamation at 8 sites of the IV experiment of the Arshan-Zelmen hospital, where reclamation work that lasted 20 years was stopped almost 50 years ago. Currently, soils belong to one type of highly transformed soils, the deep-saline agrozems. Arable (0-45 cm) and sub-arable (50-60 cm) horizons have been preserved in the soil profile. In 2018 in most areas, the content of salts and, in particular, chlorine ion increased in the subsurface horizon. These changes have not been reflected in vegetation, and the formation of plant communities characteristic of the final stages of secondary succession of light chestnut soils, not saline, continues. Hydrothermal conditions in 2021 during the observation period (May-September) can be assessed as arid – the doubly increased value of the average temperature for each month turned out to be higher than the value of precipitation that fell that month. Precipitation fell every month except July. The precipitation that fell during this period (176 mm) exceeded the average annual amount for these months of 2011-2021 by 1.3 times, and the sum of temperatures only by 2°C. Therefore, the hydrothermal conditions of the growing season of 2021 can be assessed as more favorable for the functioning of ecosystem components than in other years.

Comparison of data characterizing the salt profile of soils during the growing season showed that the content of water-soluble salts (in % per 100 g of soil) in the horizons from September to May changed in the range from -1.42 to +0.36. At different periods of observations, both unidirectional changes  in the salt content and multidirectional changes were observed in the same soil horizons. In May, the upper horizons of all soils, including virgin soils, up to a depth of 30 cm were unsalted, they remained in the same category of salinity by September. In the profile of virgin soils, salinization began from a depth of 30-40 cm and intensified downwards, reaching values of strong salinization in the horizon of 70-100 cm (1.1-2%). By the end of the growing season, the salt content in these horizons decreased to an average (0.5-1%). In soils that had previously experienced forest reclamation, the lower horizons that were slightly saline in May (80-100 cm) moved to the category of non-saline by autumn. In previously reclaimed soils under the former arable land, on the contrary, previously unsalted lower horizons have moved into the category of slightly saline. The magnitude of the change in salinity of soil horizons has a high tightness of connection (r=0.89) with the chlorine ion.

The vegetation cover is relatively sparse; the total projective coverage ranges from 35% to 73%. The average values from May to June varied from 43% to 52% and by September decreased to 47%. Throughout the year, the communities are dominated by bulbous bluegrass (Poa bulbosa) and Lerch’s wormwood (Artemisia lerchiana). Chamomile (Tanacetum achilleifolium) is present in all areas, and in some, including virgin lands, acts as a codominant. In May, the volosnets (Leymus ramosus) aspect, in June and in September – annuals Anisantha tectorum and Atriplex tatarica, respectively. The aboveground phytomass of most plant communities increases from spring to autumn from 4-5 c/ha to 10-25 c/ha. In some areas, mainly previously forested and some virgin, the maximum values were reached at the end of June and decreased by autumn due to a significant decrease in the phytomass of perennial cereals. Plant communities by species composition and dominance during the entire growing season Artemisia lerchiana and Poa bulbosa should be attributed to the pasture variant of zonal semi-shrubby-tyrsikov (Stipa sareptana) plant communities characteristic of the desolate steppe on chestnut unsalted and slightly saline soils.

The novelty of this study is associated with new quantitative data on changes in the characteristics of the main components of the ecosystems of the desolate steppes during the vegetation period.

Keywords: Caspian lowland, virgin salt flats, land reclamation, irrigated afforestation with irrigation, irrigated arable land, hydrothermal conditions, vegetation period, salinization-desalinization of soils, species richness, plant communities, aboveground phytomass.

Financing. The work was carried out within the the State Task of the Water Problems Institute of the Russian Academy of Sciences, topic No. FMWZ-2022-0002,f «Research of geoecological processes in hydrological systems of land, formation of surface and groundwater quality, problems of water resources management and water use in conditions of climate change and anthropogenic impacts».

DOI: 10.24412/1993-3916-2022-3-79-93