Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2021

Erindi/veggspjald / Talk/poster E64

Nitrogen fixation rates and cyanobacteria cover are enhanced by warming, wetting and light in a subarctic biological soil crust

Höfundar / Authors: Alejandro Salazar (1), Clara Vásquez (2), Denis Warshan (2), Ólafur Andressón (2)

Starfsvettvangur / Affiliations: 1. Landbúnaðarháskóli Íslands, 2. Háskóli Íslands

Kynnir / Presenter: Alejandro Salazar (if virtual), Ólafur Andressón (if in person)

Biological Soil Crust (BSC) is widely distributed, especially in cold and arid regions. Together, BSC and other cryptogramic ground covers contribute nearly half of the global nitrogen (N) fixation and nearly 7% of the terrestrial carbon assimilation. The rates at which BSC drives biogeochemical cycles can be altered by the environment. It is still unclear if or how cold-adapted BSC is responding to global warming and what would be the biogeochemical and ecological consequences of those potential responses. We collected blocks of a liverwort-based (Anthelia jurkatzkana) BSC from the south of Iceland, close to the Climate Research Unit at Subarctic Temperatures (CRUST) experiment, and transferred them to the laboratory for experimental manipulations. We measured short-term (2-4 days) responses of BSC to a range of temperature, moisture and light conditions. We measured biogeochemical fluxes (N fixation rates and Chl a content as an indicator of net photosynthetic rates) and the relative abundances of microbial groups (cyanobacteria, bacteria and fungi). Warming increased BSC N fixation, especially when water and light were abundant. A correlation analysis suggests that increases in N fixation rates were caused by a combination of cyanobacterial growth and increases in their metabolic rates. Our results shed light on possible responses of BSC-dominated ecosystems to short-term manifestations of climate change, such as the increasingly frequent heat waves.