Архив метки: phytocenoses

SPECTRAL CHARACTERISTICS OF DESERTIFICATED PASTURES OF BLACK LANDS (KALMYK REPUBLIC)

Arid Ecosystems

UDC 631.1: 631.4:631.6:581.5: 528.7:528.8:574.46

Yuferev V.G., Tkachenko N.A., Sinel’nikova K.P. SPECTRAL CHARACTERISTICS OF DESERTIFICATED PASTURES OF BLACK LANDS (KALMYK REPUBLIC) // Arid ecosystems. 2022. V.28. № 1 (90). P. 65-72. | PDF

Geosystems of the desert territories of Kalmykia in modern conditions function in conditions of increasing anthropogenic impact and intensity of negative weather events, including the impact of dust storms, which often leads to a significant decrease in pasture productivity, a decrease in the feed base and a significant reduction in livestock. In this regard, it is relevant to determine the spectral characteristics of desert pastures by ground methods, which provides not only the detection of the reflected energy distribution over the spectrum frequencies, which in itself is important for subsequent verification of remote sensing data of pastures, but also the possibility of obtaining the values of normalized indicators, both for plant communities and for specific plants and soil types with the formation of a spatial data base. The objects of the study are the natural phytocenoses of desert pastures of the Black Lands at the landfills: «Smushkovo»,  «Molodezhny», «Privolny», «Dl. Sagi» and «Tavn-Gashun». Geobotanical and spectrometric studies were carried out at these polygons and spatially determined data on the spectral characteristics of plant communities were obtained. Spectrometric studies of phytocenoses are carried out to assess their condition on the basis of spectrosonal surveys, both ground-based and remote. To present the results of the assessment of the spectrometric characteristics of the vegetation cover of the downed pastures: the predominant communities at the landfill and «Tavn-Gashun» were selected: bluegrass with Descurania sofia (Poa bulbosa+Descurainia sophia) with a projective cover of 45%, grasshopper bluegrass (Poa bulbosa-Stipa capillata) – with a projective cover of 40% and open soil (slightly humus sand). The studies were carried out using the PSR-1100 field spectroradiometer. The results of studies of the spectrum of reflected radiation of plant communities and underlying soils allowed us to establish the characteristic features of the distribution of reflected and absorbed energy, to compile a catalog of individual spectra and normalized indicators for them. Individual spectral characteristics were established for the phytocenosis Poa bulbosa+Descurainia sophia, the average value of reflected energy in all spectral ranges is 20.2 MW/(m2×sr×nm), the standard deviation of reflected energy is 9.90, the vegetation index NDVI = 0.208, for Stipa capillata, the average value of reflected energy in all spectral ranges is 20.5 MW/(m2 sr nm), the standard deviation of reflected energy is 12.36, the vegetation index NDVI = 0.316, for Calligonum aphyllum, the average value of reflected energy-the reflected energy in all spectral ranges is 47.2 MW/(m2×sr×nm), the standard deviation of reflected energy is 9.81, the vegetation index NDVI = 0.354. For soil, the average value of reflected energy in all spectral ranges is 30.3 MW/(m2×sr×nm), the standard deviation of reflected energy is 9.28, the vegetation index NDVI = 0.106. The highest average value of NDVI was noted for Calligonum aphyllum.

Keywords: geosystem, analysis, desertification, degradation, spectrometry, satellite images, phytocenoses, verification, vegetation indices, albedo.

Financing. The work was carried out within the framework of the State Task of the Federal Research Center of Agroecology of the Russian Academy of Sciences No. 0713-2019-0001 “To conduct theoretical and geoinformation modeling, monitoring, forecasting of degradation processes of components of agroforestry landscapes based on aerospace research in forest-steppe, steppe and desert zones and to develop ways to manage anti-degradation agroforestry technologies to prevent desertification of lands, increase their fertility and form an ecological framework” (state registration No. AAAAAA-A-116122010038-9).

DOI: 10.24412/1993-3916-2022-1-65-72

FEATURES OF THE SEASONAL DYNAMICS OF THE STRUCTURE OF PHYTOCENOSES ON THE SANDY LANDS OF THE SOUTH OF THE EUROPEAN TERRITORY OF RUSSIA

Arid Ecosystems

UDC 581.5

Vlasenko M.V., Trubakova K. Yu. FEATURES OF THE SEASONAL DYNAMICS OF THE STRUCTURE OF PHYTOCENOSES ON THE SANDY LANDS OF THE SOUTH OF THE EUROPEAN TERRITORY OF RUSSIA // Arid ecosystems. 2022. V.28. № 1 (90). P. 114-123. | PDF

Species diversity, yield, share participation and seasonal variability of species in natural and artificially created phytocenoses in the sandy lands of the southern European territory of Russia are considered. The role of the influence of moisture conditions on the formation of species diversity in different communities is explained. The Tsimlyansk sand massif was monitored using the methods of ecological and geobotanical surveys. It is established that the main mass in the phytocenoses of the Tsimlyansk sand massif is occupied by species from the family Asteraceae, Fabaceae and Poaceae. The herbaceous-shrub layer includes 183 species from 41 families. The Simpson index shows that for the territory of excessive moisture (II), the dominance of species of the Poaceae family is most pronounced. In areas of sufficient and variable moisture (III), moderate moisture (IV), as well as in areas of insufficient complex moisture and complex severely insufficient moisture under the sandy hillocks and moderate moisture in the grove and eroded sands (V), species of the Asteraceae, Fabaceae and Poaceae families dominate. The index of similarity of the species composition of the Jacquard shows that the most similar in terms of species diversity of the territory are: complex insufficient (Va) and complex severely insufficient moisture under the sandy hillocks and moderate moisture in the grove and eroded sands (Vb) – 90%; moderate moisture (IV) and complex severely insufficient moisture under the sandy hillocks and moderate moisture in the grove and eroded sands (Vb) – 89%; sufficient and variable moisture (III) and moderate moisture (IV) – 87%; excessive moisture (II) and moderate moisture (IV) – 87%. In the territory of moderate moisture (IV) in the studied phytocenosis, the largest mass was formed by cereals: Agropyron cristatum L., A. elongatum (Host) P. Beauv., Festuca valesiaca Gaudin, F. beckeri (Hack.) Trautv. and Poa pratensis L., Artemisia campestris L. and Galium verum L. predominated in various grasses. On average, the share of cereals in the community was 66.5%, the share of mixed grasses was 33.5%. In the territory of sufficient and variable moisture (III), the largest phytomass was also formed by species from the Poaceae family: Elytrigia repens (L.) Nevski and Agropyron elongatum (Host) P. Beauv., Agropyron cristatum L., Artemisia campestris L., Artemisia vulgaris L. and Artemisia arenaria DC had a great influence on the growth of phytomass. To stop the processes of degradation, improve the economic condition and increase the fertility of pasture ecosystems in large areas, it is proposed to fix mobile sands and restore pastures with the help of selected multicomponent grass mixtures. The experiment on studying the productivity of artificially created phytocenoses for restoring and increasing the productivity of natural pasture ecosystems was carried out on the vegetation sites of the lysimetric complex of the Federal Research Center of Agroecology of the Russian Academy of Sciences. The most promising on sandy substrates is a grass mixture with Agropyron cristatum L., Artemisia arenaria D.C., Medicaga sativa L. and a yield of 228.6-246.7 g/m2, as well as a grass mixture with Agropyron cristatum L., Agropyrom elangatum Host.P.B., Bromus inermis Leyss. and a yield of 184.4 g/m2.

Keywords: phytocenoses, species diversity, sand massifs, pasture ecosystems.

Financing. The work was carried out within the research No. AAAA19-119042290014-5 “Theoretical foundations of water resources management in the forest-agrarian development of arid territories of the Russian Federation on the basis of a dynamic model of the water balance of the region, mathematical modeling of the processes of formation and dynamics of groundwater and surface waters, assessment of the impact of climate change and anthropogenic loads on the agro-resource potential and forest-growing conditions”.

DOI: 10.24412/1993-3916-2022-1-115-124

THE CLIMATIC FLUCTUATIONS IN DRY STEPPES AND THEIR ROLE IN THE PROCESS OF REGENERATION

Arid Ecosystems

Pugacheva A.M. The Climatic Fluctuations in Dry Steppes and Their Role in the Process of Regeneration // Arid ecosystems. 2020. V. 26. № 3 (84). P. 14-22. | PDF

For the first time a research paper presents the results of the analyses of moisture-providing during the active growing seasons in dry steppes. The climatic fluctuations were examined together with the defining their characteristics. Contrary to the common opinion, that the steppe zone receives the highest rainfall in summer and that fact becomes its special feature including subzones, the analyses of 64 years show that the dry steppes of Lower Volga region received the highest rainfall in summer only in 39 % of years, in spring – in 27% of years and in autumn – in 34% of years. The time-series analysis during the seasons of moisture-providing for more than 50 years identified the general trend of decrease in summer rainfall and the increase of spring and autumn rainfall. The processing of time-series by  exponential smoothing and the regression analysis points to the rate of humidity increase in spring after the critical years of 1990 and 1991, which is proved by Student’s t-test (probability 0,00005) together with the humidity decrease in autumn (probability 0,01). These features characterize the regeneration processes of secondary phytocenoses on fallow lands in the form of domination of loose bunch cereaks and dense cereals in them because the moisture-providing in late spring (May) and early summer (June) has the primary importance for their development. In addition, the characteristics of moisture-providing show a tendency towards aridization. The number of species of Poaceae family  in the examined phytocenoses is 28 with 24.5% of representation. Moreover, this fact characterizes the existence of ephemeral plants and ephemeroids in the plant community, because their vital activity mainly depends on the spring rainfall. The number of their species is 8% of the total.

Keywords: climatic fluctuations, dry steppes, regeneration, plant communities, phytocenoses, exponential smoothing, regression analysis.

DOI: 10.24411/1993-3916-2020-10102