Climatic Effects on Desert Microorganisms

You probably already know that soil microorganisms are crucial in nutrient cycling and decomposition of organic matter. These are fundamental functions for maintaining life in the soil and our planet.

However, you might have yet to hear of a microbial community in desert soils before, the Biological Soil Crusts (CBS).

Who makes up CBS, and why they are important.

Living in desert environments is a challenging task. Organisms must adapt to low humidity, high solar radiation, and high temperatures. The microorganisms that manage to thrive under such conditions are called xerophiles.

Surviving in the desert makes the soil nutrient-poor. Therefore, it's not surprising that the predominant microorganisms are photoautotrophs. These are organisms capable of producing the nutrients they need through solar energy. After all, sunlight is abundant.

Thus, CBS mainly comprises cyanobacteria, a type of photosynthetic bacteria. They also house fungi, lichens (associations of algae and fungi), mosses (very simple plants), and non-photosynthetic bacteria.

The organic matter resulting from the metabolism of cyanobacteria initiates a trophic chain capable of cycling nutrients and altering the permeability and texture of the soil. CBS, therefore, stabilizes the newly formed soil.

This aspect is crucial in desert areas where soil formation is slow and can be quickly devastated.

The effect of climate change on CBS

Although microorganisms are adapted to desert conditions, the increase in global temperature and consequent decrease in relative air humidity affect the composition of microbial communities found in CBS.

Especially concerning the population of lichens, responsible for capturing nitrogen from the air (nitrogen fixation process) and transforming it into a form that other microorganisms can absorb. Without nitrogen, the community's growth is limited, including plants, herbivorous animals, and carnivores. This fact leads to a disastrous chain reaction in the food web.

The consequence is desertification – an unproductive area.

Efforts to mitigate these effect

Scientists transplant these structures to more affected areas. However, the effect has yet to be sufficient to recover lichens.

There are also educational campaigns. For example, in the USA, it is common to see signs informing visitors about the effects of destroying biological soil crusts on the ecosystem.

However, these measures still need to be improved. Combining all of this with more effective strategies to mitigate the climatic effects on a large scale is necessary.