Succession of Methanotrophic Community Structure along the Chronosequence of a Deglaciation in the High Arctic

Global glaciers have receded rapidly, and Svalbard is one of the places in the high Arctic where deglaciation causes rapid changes in landscape due to climate change. The reduction of glaciers expands exposed soil surface and may enhance biological decomposition by an increase in microbial activity with oxygen availability, which may cause a change in methane flux in the Arctic and consequently global carbon cycle. While primary succession following glacier retreat has widely been studied in plant communities, microbial succession, particularly that of methanotrophic community is still poorly understood. In this study, microbial abundances and the shifts in methanotrophic community structure were analyzed along a successional gradient in a 100-year glacier foreland of the high Arctic. The abundance of bacteria, fungi, and archaea showed a significant differences along the successional time, and the abundance near the glacier front (the early stages) was the lowest. The abundance of methanotroph (pmoA) showed a significant difference along the successional time, while the abundance of methanogen (mcrA) did not exhibit a significant difference. Diversity of methanotroph increased sharply at the early stages and these high levels of diversity were maintained till the latest stages. We found that methanotrophic community structure changed along the successional time which was mediated by soil physicochemical properties including soil organic carbon and total nitrogen. Our results indicate that the methane oxidation may be enhanced by the increase in methanotrophic abundance and diversity along the successional time, and soil physicochemical properties and successional time play a key role in structuring methanotrophic community in different stages of succession in glacier foreland. This research will contribute to improving uncertainty of estimation of global methane sink.