Abstract:
The Antarctic continent is widely considered to be one of the most hostile biological
habitats on Earth. Despite extreme environmental conditions, the ice-free areas of the continent,
which constitute some 0.44% of the total continental land area, harbour substantial and diverse
communities of macro-organisms and especially microorganisms, particularly in the more “hospitable”
maritime regions. In the more extreme non-maritime regions, exemplified by the McMurdo Dry
Valleys of South Victoria Land, nutrient cycling and ecosystem servicing processes in soils are
largely driven by microbial communities. Nitrogen turnover is a cornerstone of ecosystem
servicing. In Antarctic continental soils, specifically those lacking macrophytes, cold-active free-living
diazotrophic microorganisms, particularly Cyanobacteria, are keystone taxa. The diazotrophs are
complemented by heterotrophic bacterial and archaeal taxa which show the genetic capacity to
perform elements of the entire N cycle, including nitrification processes such as the anammox reaction.
Here, we review the current literature on nitrogen cycling genes, taxa, processes and rates from
studies of Antarctic soils. In particular, we highlight the current gaps in our knowledge of the scale
and contribution of these processes in south polar soils as critical data to underpin viable predictions
of how such processes may alter under the impacts of future climate change.
