Pyrogenic factor and its role in the development of desert-dry steppe vegetation: environmental risks for pasture ecosystems

Introduction. The impact of fires on local changes in plant communities is an urgent environmental problem in many regions of the world. The scientific novelty of the research is confirmed by the fact that analyzing the phytocenoses reaction to pyrogenic effects is important due to the fact that vegetation is the basis of the native animals habitat and their food resources, as well as ecosystem processes. The purpose of the work is to assess the environmental risks of reducing productivity as well as forecast the recovery time of desert - dry - steppe pasture phytocenoses under the influence of a pyrogenic factor. Materials and methods. Patterns of post - pyrogenic successions of vegetation cover were revealed over the period 2021-2024 in areas exposed to fires in 2020. Research methods included field geobotanical descriptions and data analysis using Microsoft Excel, STATGRAPHICS+5.0 software. Statistical indicators of yield dynamics were calculated for each type of pasture and various soil conditions using an adapted data series analysis technique during the studying of the time aspect of the phenomenon. A cluster analysis based on the “nearest neighbor” principle was carried out using an agglomerative hierarchical classification algorithm. Results and discussion. Fires are a powerful factor affecting vegetation and soil, leading to the transformation of natural ecosystems. On average, over 4 years, the yield of background formations on sandy soils reached 0.80-1.06 t/ha, on loamy soils - 0.81-1.01 t/ha. The yield of pyrogenic formations on sandy soils did not exceed 0.57-0.85 t/ha, on loamy soils - 0.56-0.64 t/ha. There is an increase in the average rate of growth of pyrogenic formations yield, especially: breadbasket - white - wormwood - prutnyak on brown sandy loam soils (98%), white - wormwood - Breadbasket on brown sandy loam soils (43.4%), feather grass on brown loamy soils (46.7%), feather grass (Stipa capillata) on brown sandy loam soils (45.1%). Conclusion. In the year of the summer - autumn fires, aeolian processes are intensifying, species diversity and projective cover of the grass stand sharply is decreasing. An aerotope is formed according to the surface type of filling, and the loss of Artemisia lercheana reduces the productivity of autumn - winter and early spring pastures. From the second year after the fire, the average yield growth rate of all pasture grasses increases significantly, the percentage participation of Stipa, Agropyron, Festuca valesiaca, Bassia prostrata, Koeleria macrantha, Carex stenophylla, Tanacetum millefolium, Galatella villosa, Calamagrostis epigeios increases in the composition of communities. The natural restoration of the herbage gross yield and the projective cover on the burned areas till the background level does not occur earlier than 3, 4 years after the fire. Suggestions for practical application and direction of future research. Understanding the response of plant communities to fire makes it possible to develop effective strategies for the restoration and stabilization of pyrogenic formations in order to increase the supply of nutrients to the soil and improve its hydrological function. The results of the research can be useful in the use and restoration of fire - affected areas for using them as pastures.