Abstract:

In recent years, global climate change has become increasingly serious, with a wide range of impacts. The polar regions are the earliest to respond to the impacts of climate change. Global climate change has led to the rapid growth of dominant plants such as vascular plants and graminoids in the Arctic. Salix arctica, Bistorta vivipara and Luzula confuse are the three most common dominant species in Ny-Ålesund (Arctic), which are potentially important for the composition and distribution of bacterial communities in the Arctic soil ecosystem. Microorganisms are highly sensitive to environmental changes, but also play a crucial role in the global carbon and nitrogen cycles and polar ecosystems balance. Nitrogen is one of the main nutrient limiting factors for plant growth. In order to study the effect of nitrogen on bacterial community diversity in plant rhizosphere soil in Arctic coastal area, 16S rDNA amplicon sequencing was used to analyze the diversity of bacterial community in three typical types of plant rhizosphere soil and background soil in Ny-Ålesund (Arctic) from 2014 to 2016. The results showed that the soluble inorganic nitrogen (NO₂^– -N, NO₃^– -N, NH₄⁺-N) was significantly correlated with the bacterial community in the rhizosphere soil of the three plants (P < 0.05). Nitrosomonadaceae_uncultured and Subgroup 6_norank are the dominant core groups of Salix arctica rhizosphere soil, which have a significant correlation with NO₂^– -N (P < 0.05). Subgroup 6_norank and JG34-KF-361_norank (Rhizobiales) show a significant correlation with NO₃^– -N (P < 0.05) in rhizosphere soil of Bistorta vivipara. Acidimicrobiales_norank and Anaerolineaceae_uncultured have a significant correlation with NH₄⁺-N (P < 0.05) in rhizosphere soil of Luzula confuse. Furthermore, concentration of three soluble inorganic nitrogen salts and relative abundance of these core groups show consistent interannual variability. It can be seen that soluble inorganic nitrogen plays an important role in the diversity of bacterial community, especially the change of core bacterial community in the rhizosphere soil of Arctic plants.

Key words: rhizosphere soil, diversity, dominant core groups, geochemical factors, nitrogen cycle, Arctic