The dynamics of the perennial grass crops communities on the restoration succession gradient

Abstract

The trends of the coenoflora structure dynamics of the perennial grass crops communities were characterized on the gradient of restorative succession in the conditions of the steppe and forest-steppe zones of the Southern Urals. Using an agglomerative cluster analysis, four community groups have been identified, which corresponds to the stages of succession and reflecting the age of the communities (from 1 to 16 years or more). It is demonstrated that the succession gradient complicates the species composition, the species richness of the communities increases by almost 2 times. An analysis of the activity index change for the coenoflora core species at each stage has been carried out. It has been revealed that the activity of sown herbs species decreases, while the total activity of well-eaten species as well as the feed value of the whole phytocoenoses increases with the age of communities. A community of each stage of succession is marked by a group of highly active species, the functional composition and coenotic affinity of which changes. The activity of apophyte species increases while the activity of synanthropic ones decreases. There is a natural complication of the phytosociological spectrum from species of affine to classes of synanthropic vegetation Sisymbrietea and Artemisietea to species of classes of natural vegetation meadows (Molinio-Arrhenatheretea) and steppes (Festuco-Brometea). At the same time, the most active substitution of synanthropic species for natural ones occurs after the second stage of succession, i.e. its significant acceleration is observed after the age of 11 years. According to the results of the ordination analysis (DCA-ordination) with an additional assessment of the contribution of environmental variables, the leading in the differentiation of the species composition of communities is the factor of the age of communities, the factor of humidification of habitats makes a smaller contribution. According to the results of the comparison of the studied phytocoenoses with the data of weed, meadow and steppe communities from the database of non-forest vegetation of the Southern Urals (1660 releves), the central position of perennial grass crop communities on the gradient of restorative succession from disturbed arable land vegetation to natural (steppes) (steppes) and quasi-natural (meadows) vegetation types is demonstrated. Thus, a high importance of perennial grass crops for the creation of stable phytocoenoses of high forage value, which can be used for the restoration of biodiversity in the forest-steppe and steppe regions, is revealed.