Lichens and mosses , together with the green algae that we find in water sources and on stones and understory trunks, are popularly classified in a group of organisms called biological soil crusts or plant biobark , although in taxonomy they are part of very kingdoms. evolutionarily distant.
Although many times in our walks through the forest they go unnoticed, these beings occupy neither more nor less than 12% of the entire earth’s surface, which is equivalent to about 18 million km² of land , concentrating mainly in arid areas. In addition, the ecological role of the biofilms is more important than one might think, as they help to control the movement of water and protect the soil from erosion; fix carbon and nitrogen; they alter the albedo effect of the earth; they control nutrient fluxes, and by extension, influence biodiversity at the local level.
Now that we know their ecological function, let’s see in detail how they differ:
Mosses
Also known as bryophytes , they are non-vascular plants, that is, they do not have a stem or flower and their leaves are not true. As they feed on photosynthesis, they usually have a greenish color and we will find them in humid and shady areas. Sometimes you can find small “antennae”, called sporophytes, which will make them unmistakable. Here you have a free guide to mosses from the Spanish Society of Briology.
Lichens
They are an association of two organisms in symbiosis, specifically an alga or a cyanobacteria and a fungus. The former produce food through photosynthesis and serve it to the fungus, which in turn provides moisture, a substrate for the survival and protection of the algae. They come in multiple colors and shapes and we can find them on any substrate and environment, from rocks to dry tree branches. Sometimes we can see on its surface some “trumpets finished in crater”, called ascocarps or ascomas, which are their reproductive structures. As they are no less important, here you have a free dichotomous key from the University of Trieste and the University of Valencia.
Now that we know the differences between these groups of organisms, it is important to note that, despite their ability to regulate certain environmental and nutritional conditions at the local level, these organisms are also being seriously affected by climate change and changes in use. ground. According to a study published in Nature Geoscience by researchers from the University of Almería and the Max Planck Institute for Chemistry in Germany, the area covered by these communities could decrease by up to 40% by 2070, having serious consequences for some ecosystems.
So, if you are one of those who still likes to make the nativity scene for Christmas, think twice before taking a handful of bio-bark home with you ; where they do the most service is where they grew up. For some reason, biofilms are also known to be “the living layer of the Earth.”
References:
Rodriguez-Caballero, E., Belnap, J., Büdel, B., Crutzen, PJ, Andreae, MO, Pöschl, U., & Weber, B. (2018). Dryland photoautotrophic soil surface communities endangered byglobal change. Nature Geoscience, 11 (3), 185-189. https://doi.org/10.1038/s41561-018-0072-1
