Peculiarities of Algae Groupings of Post-Pyrogenic Steppe Biocenoses in "Askania Nova" Biospheric National Park
The paper deals with the peculiarities of steppe biocenoses soil algae grouping makeup with various post-pyrogenic development periods after one- and two-fold fire effect on the territory of “Askania Nova” Biospheric National Park natural core set. It was determined that pyrogenic factor had essential impact on steppe algo-groups formation stimulating their ability to quickly adapt to changing environmental conditions. Number of species, major segments relationship, dominant complex compound as well as life-form spectrum were different in post-pyrogenic algo-groups. In steppe biocenoses, that had been twice exposed to pyrogenic effect, the increasing of total amount of algae species, especially heliophilous Cyanophyta, was observed. Among the dominant species of the studied biocenoses, specimens with various degrees of resistance to pyrogenic factor were noted. The most saturated ones in all researched biocenoses were formed in summer and spring on the basis of apparent algae community structure. In summer the most variable species were Cyanophyta, Chlorophyta, Baccilariophyta. In spring the amount of Cyanophyta increased in communities, while in autumn these were Eustigmatоphyta and Xanthophyta varieties. The largest amount of algae varieties was registered on the surface of 5-cm soil layer. At the deeper layer (up to 15 cm) the amount of species of Cyanophyta variety decreased dramatically in contrast to other species, especially Baccilariophyta.