Cyanobacteria and Algae in Biological Soil Crusts of Frost Boils in the Mountain Tundra of the Urals

Abstract

Diversity of cyanobacteria and eukaryotic algae was recovered from biological soil crusts formed on bare spots in tundras of the Ural mountains. The research was carried out in two typical tundra types, dominated by shrub-moss-lichen and dwarf birch-lichen-moss communities. In total, 46 species belonging to five divisions were identified: Cyanobacteria (19), Ochrophyta (1), Bacillariophyta (2), Chlorophyta (22), Charophyta (2). Core species of the biological crusts come from Cyanobacteria (Stigonema minutum, Gloeocapsopsis magma, Schizothrix fuscescens, Dasygloea cf. lamyi, Fischerella muscicola, Nostoc commune, Scytonema hofmannii) and Chlorophyta (Sporotetras polydermatica, Coccomyxa simplex, Elliptochloris bilobata, E. subsphaerica, Lobochlamys culleus, Pleurastrum terricola). The low diversity of algae and cyanobacteria results from harsh environmental conditions of their habitat: extreme fluctuation of upper ground temperatures, acidic soils with low base content, and reduced levels of nitrogen, phosphorus and other crucial biogenic elements. The total number of cyanobacterial and algal cells per g of soil was estimated at 0.03 to 34.19 million. Based on the acetylene reduction method, the average nitrogen fixation rates in biological crusts ranged from 0.009 to 0.015 mg С2Н4 m–2h–1. The activity varied between soil crust types from 1.48 to 2.25 mg С2Н4 m–2h–1. In future, regular observations are planned on the studied sites to reconstruct and predict succession processes in cryogenic landscapes under mountain tundra conditions.