UDC 911.2 (470.56)

Khoroshev A.V. STABILITY OF PHYTOMASS DYNAMICS IN PROTECTED LOW MOUNTAIN-STEPPE LANDSCAPES AND PASTURES IN THE SOUTHERN URALS // Arid ecosystems. 2022. V.28. № 3 (92). P. 3-13. | PDF

In the steppe zone, the high sensitivity of the vegetation cover to humidification contrasts raises the question of the dependence of the intraseasonal dynamics of phytomass on the spatial pattern of vegetation cover and relief in a landscape. We performed a case study in the Aituarskaya steppe (Orenburg region) to test the hypothesis about the inequality of the spatial factors of variability of functioning under the conditions of the reserve regime and pasture impact. Based on the frequency of occurrence of five gradations of deviations of the intraseasonal increments of the vegetation index NDVI from the mean values, the measure of instability of the types of dynamics of green phytomass (Shannon’s index) was calculated. The relationship between the types of dynamics and the types of natural boundaries, due to belonging to the relief forms with the characteristic types of phytocenoses, has been established. Areas of the most unstable phytoproductive functioning are characteristic of valleys with meadow steppes. The reserve regime stabilizes the dynamics of phytomass due to a higher subordination to landscape-scale climatic processes. On grazed areas, frequent changes in the variants of phytomass increments are more characteristic and dependence on local factors (e.g., stoniness, groundwater level) increases. In the pasture area, in some places, the dominant dynamics becomes with an intensive late spring accumulation of phytomass and a small decrease or renewal by the end of summer due to an increase in the proportion of non-palatable and grazing-resistant species.

Keywords: steppe, landscape, reserve, pasture, phytomass, NDVI, seasonal dynamics, stability, relief, Urals.

Acknowledgements. Expressing gratitude to D.E. Sharova, O.M. Podgorny, I.V. Volovinsky, G.M. Leonova for participation in field research and arrangement of remote materials and to reviewers for constructive comments.

Financing. The study was carried out with the financial support of the Russian Foundation for Basic Research, project No. 20-05-00464 «Spatial structure as a factor of stability of landscape functioning», 2020-2022.

DOI: 10.24412/1993-3916-2022-3-3-13