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Polar areas: what happens when the ice disappears?


When, as a result of climate change, ice melts in the polar areas, a rapid colonization of the deglaciated surface occurs. The first visible signs of change are the appearance of cryptogamic covers, structures formed by lichens, algae or moss, which colonize soils that, after thousands of years under a dense layer of ice, are left uncovered.

Source: Chile Desarrollo Sustentable

March, 2021.- The development of these covers is greatly increasing in polar regions, but what changes occur in the soil and what do they involve? That is what the researcher of the National Museum of Natural Sciences (MNCN-CSIC), Asunción De los Ríos, together with colleagues from the Center for Functional Ecology of the University of Coimbra (CFE), among other institutions, has analyzed in an article published in the journal Science of the Total Environment.

Soil ice from both polar regions 

After analyzing soils from the two polar regions, namely Iceland and Livingston Island (Maritime Antarctica), they have found that soils from deglaciated areas with cryptogamic canopies are more fertile and show greater complexity and diversity.
 "The covers stimulate soil development, make them richer and have greater bacterial diversity, as well as increase their enzymatic potential and functioning rates", says the MNCN researcher.
"This fact, which a priori may seem good, confirms that the ecosystem is changing. In fact, it shows that polar ecosystems are changing their structure, but we don't know what effects this may have in the long term", says Jorge Duran, a researcher from the Centre for Functional Ecology and another of the investigators in this study.

The changes caused by the development of cryptogamic covers vary according to their ability to modify soil characteristics. In this study, they analyzed layers dominated by macroalgae, lichens or mosses, and found that different types of cryptogamic covers can modify the soil at different rates and ways.

Therefore, the scientist suggests that the degree of modifications in polar soils, due to the expected increase in the extent of cryptogamic covers in a context of climate change, will largely depend on what type of cryptogam is able to thrive under the new environmental conditions.

The role of cryptographic covers
In addition to lichens and mosses, cryptogamic covers can contain microorganisms such as bacteria, cyanobacteria, algae and fungi. A large part of the earth's surface, including soils and rocks, is covered by these structures. The relevance of these layers in polar zones is due to the fact that, in addition to being the first to occupy soils when the ice retreats, they favor the development of other more complex communities. 

  "The cryptogamic cover is the previous colonization that will later give way to the appearance of superior plants and, with this study, we help to understand how it facilitates soil development. For example, in the study we provide information on how microbial diversity or greenhouse gas fluxes between the soil and the atmosphere change when the soil is colonized by different types of cryptogamic cover", Duran explains.
"The extent of deglaciated areas due to the effect of climate change is increasing in many regions of the planet, hence we need to know the dynamics of colonization of these areas and the role played by cryptogamic covers in the biological process after the retreat of glaciers", concludes De los Rios.
This work is part of the CRYPTOBIOS project (CTM2015-64728-C2-2-R, MINECO/FEDER, EU) and is the result of the collaboration of researchers from MNCN-CSIC, Centre for Functional Ecology (University of Coimbra, Portugal), Institute of Landscape Ecology (University of Münster, Germany) and Icelandic Institute of Natural History (Iceland).