Soil microbial biomass, activity and community composition along altitudinal gradients in the High Arctic (Billefjorden, Svalbard)
The unique and fragile High Arctic ecosystems are vulnerable to proceeding global climate warming. Elucidation of factors driving microbial distribution and activity in Arctic soils is essential for comprehensive understanding of the ecosystem functioning and its response to environmental change. The goals of this study were to investigate the microbial biomass, activity, microbial community structure (MCS) and its abiotic controls in soils along three elevational gradients in coastal mountains
... of Billefjorden, Central Svalbard. Soils from four different altitudes (25, 275, 525, and 765&thinsp;m above sea level) were analysed for a suite of characteristics including temperature regimes, organic matter content, base cation availability, moisture, pH, basal respiration, and microbial biomass and community structure using phospholipid fatty acids (PLFA). We observed significant altitudinal zonation of most edaphic characteristics reflected by soil microbial properties. The microbial biomass and activity normalized per unit of organic carbon significantly increased with elevation. The two dominant microbial groups, fungi and bacteria, had different habitat preferences, resulting in high fungi to bacteria (F&thinsp;/&thinsp;B) ratios at the most elevated sites. The changes in MCS were mainly governed by the bedrock chemistry, soil pH, organic carbon content and soil moisture. While the direct impact of summer soil temperature regimes on soil microbes was likely negligible, it´s influence on plant distribution along the gradients have strong implications for edaphic conditions and consequently also for soil microbes. Our results highlight the need to consider unvegetated high elevation areas as hotspots of microbial activity and important habitats within the High Arctic ecosystem.