Climate change is the greatest environmental threat of our time. It is making itself felt both regionally and globally through changes in temperature, precipitation and wind conditions. Research into air quality is an important part of climate research. For this issue occasion, ''Terhi Tuominen'' and ''Jitan Patel'' chose an Usnea, a root-like structured bearded lichen, as the coin's motif. It acts as a natural air quality measuring device. The lichens hanging from the bark of coniferous and deciduous trees are alternately moist organisms that are able to use various water sources such as rain, fog, dew and water vapour for their photosynthesis. Lichens interact with their immediate environment in a fluid equilibrium between drying out and remoistening, nutrient uptake and leaching as well as photosynthesis and respiration. They have no active control mechanisms such as stomata to reduce transpiration and CO2 uptake or roots and vascularisation to supply water, but exchange resources passively over their entire surface. During their metabolic activity, they accumulate substances absorbed from the environment in their organic material. This applies both to environmentally harmful substances such as sulphur dioxide, heavy metals or an excess of nitrogen and to carbon dioxide and water resources. The isotope signature of lichens can be used to gain insights into CO2 and water cycles and local climate changes can be detected with the help of so-called lichen mapping. |
