Dynamics of vegetation changes in oil and salt-contaminated oligotrophic ridge-hollow mire complexes after reclamation (Middle Pre-Ob region, Khanty-Mansi Autonomous Okrug – Yugra)

Abstract

Oligotrophic ridge-hollow and ridge-hollow-pool complex mires are widely distributed in the central part of West Siberia, including many oil fields of the Middle Pre-Ob region. The article considers the dynamics of re-vegetation of oil and salt-contaminated areas of these mire types subjected to reclamation. Survey materials for 2–3 years and 15 years after reclamation allow to identify the main trends in vegetation restoration in the short and medium term. The reversible oligotrophication of ridges manifests in a relative decrease in the participation of the meso-eutrophic species on contaminated mire sites. In the hollows, however, the similar trend can be traced only in relation to oil-contaminated sites, whereas in the salt-contaminated hollows, the strong eutrophic conditions last. In the medium-term perspective, most typical oligotrophic hollow species, with the exception of Eriophorum russeolum and Oxycoccus palustris, were unable to recover. In the course of dynamic changes in the vegetation, the leading role in recovery successions gradually passes to mesotrophic and eutrophic species possessing massive root systems and aerenchyma – Eriophorum angustifolium, Phragmites australis, Carex rostrata, etc. Restoration of the moss layer is several years behind that of the grass layer, and due to the lack of competition, the participation of liverworts in it is of great importance, especially in salt spills. At the same time, among mosses as in the case of vascular species mesotrophic components are the main dominant ones15 years after reclamation.