Breathtaking
As a shared feature, BSC organisms lack the ability to maintain or regulate their water content. This inability makes these organisms highly dependent on water that is available in their surroundings. Unlike higher plants, lichens, green algae, mosses and cyanobacteria can survive long periods in a dessicated or completely dried out state (i.e. they can live in areas prone to drought or in freezing temperatures). These extremophile characteristics allow cyanobacteria and green algae communities to be the conquering pioneers of barren or disturbed areas \cite{Belnap_2016a}. This initial wave may be followed by the encroachment of mosses and lichens, especially where enough water is present. BSCs contribute to the development of an ecosystem as BSCs prime soils for plants through fertilisation. Cyanobacteria are especially important because they can bind to atmospheric nitrogen (N), which is often a limiting nutrient for plant growth. BSC organisms also fix carbon (C) during photosynthesis, taking the element from atmospheric CO2. In turn, this helps reduce greenhouse gases and climate change. With these traits, BSCs are responsible for the fixation of up to 7% of carbon in comparison to net primary production by land plants, whilst they also account for ~50% of the biological nitrogen fixation on land \cite{Elbert_2012}.
Our study was conducted in cold ecosystems (i.e. at the poles and in alpine environments) and published in the journal Biogeoscience \cite{Jung_2018}. We showed that these soils, which are dominated by BSCs, are CO2 sinks. This means that carbon fixed by BSC organisms is stored in the permanently frozen soils where, due to low temperatures, almost no breakdown of organic matter can occur. Therefore, growth and establishment of BSCs in these cold ecosystems means CO2 is fixed and stored in the soils rather than being released into the atmosphere (Figure 2).