Dynamics of steppe phytocenoses in the first years after fire (for example, monitoring section № 1 in the "Burtinskaya steppe" reserve "Orenburgsky")

The steppe zone in the Orenburg region is subject to the strongest anthropogenic load, most of the steppes are plowed, the rest of the land suited for grazing or are not processed and are a reservoir. Another serious threat to the conservation of biodiversity in the region are wildfires. Their influence is reflected in all components of the phytocenosis, causing a significant transformation of communities. The degree of impact may be different depending on the frequency of fire, timing and intensity. In recent years, the spread of steppe fires and their frequency acquired extraordinary proportions. Climatic conditions (dry, hot summers and long atmospheric drought) contribute to the spread of fires in large areas. The main cause of fires is human factor. Even in the area of the nature reserve “Burtinskaya steppe” the average frequency of fires is 1 in every 5-6 years. Opinions about the impact of fires on steppe vegetation varied from a fully negative value before consideration of fires as a natural and sometimes necessary factor for the maintenance of the steppes. In order to trace the restoration of steppe ecosystems after Pala, we studied the dynamics of the reserves of the top phytomass in 2015-2016. The article considers the initial stages of post-fire changes in Festuca valesiaca, Stipa zalesskii, Artemisia austriaca, Herbae stepposae community with Spiraea crenata. Studies have shown how the community after the fire is accumulated and distributed components of aboveground phytomass. A comparison with similar Stipa zalesskii, Poa transbaicalica, Herbae stepposae community with Spiraea crenata. Revealed a change of dominant species in phytocenosis, the reduction of the total projective cover compared to the control. In the burning community marked the emergence of weed species: Sisymbrium polymorphum (Murray) Roth., Chenopodium strictum Roth, Draba nemorosa L.