Understanding Arctic browning from macro to nano

The occurrence of extreme winter weather events has increased in the sub-Arctic.

Rapid temperature increase during these events can result in a marked reduction or total loss of snow cover leading to stress responses or dieback of plants causing ‘browning’. Shifts in the biogeochemical processes driving ecosystem carbon and nitrogen (N) dynamics are possible consequences.

However, very few studies have connected plant responses with responses in the biological soil crusts (BSC) consisting of a network of lichen, mosses, cyanobacteria and their symbiotic and decomposing bacteria and fungi.

As BSC support essential ecosystem functions including colonization, soil stabilization, water retention and N fixation, it is critical to understand how BSCs are influenced.

This project aims to understand the resilience and functioning of BSC communities and quantify effects on the N cycling.

We will combine winter temperature and icing manipulation experiments in the field at two locations (N Sweden and Greenland) with laboratory manipulations using controlled freeze-thaw cycles.

We will further couple stable isotope tracing methods with novel analytical approaches by using ‘nanoSIMS’ and microfluidic ‘soil chips’, as well as quantitative assessment of microbial communities and their functional genes.

Finally process modelling will constrain future estimates of subarctic N turnover and provide input to one of the most critical unknowns for impacts of arctic browning.