Arid and semi-arid ecosystems usually don’t have a lot of vegetation to cover the soil. In these cases, the soil is sometimes covered by a biological soil crust, that is communities of living organisms that live in the top of the soil. There are many areas in the United States that are covered by this kind of crust, including some agricultural areas.
The organisms that compose and live in this kind of crust are, in many proportions, fungi, lichens, cyanobacteria, bryophytes, and algae. The main one, and most important, is the cyanobacteria. It not only lives in the crust but also produces sub-components via photosynthetic processes. That enriches the soil and creates a biological binding material that brings non-organic crust particles together.
The crust is the first layer of the soil, and it can protect it against many outside circumstances. It may just be a 1mm layer, but it can make a difference in many aspects of the soil. Here are some of the ways it can influence the land’s health.
- Water infiltration
Biological soil crust can influence greatly the levels and proportions of water in the soil. The way that it does that will vary depending on the specific microorganisms living in the soil and their proportions. They can increase the soil’s roughness, thus increasing infiltration. Or they can reduce water drainage with the presence of cyanobacterial filaments.
- Plant health
The increasing presence of organisms in the biological crust can highly influence the rates of plant and seed germination. It is also proved beyond doubt that soils with biological crust provide a healthier environment for plants to grow. The nutrient content is higher, plants survive longer and their biomass grows larger.
- Soil stability
Arid soils are very prone to erosion. They take a long time to form and can deteriorate easily by outside forces like heavy occasional rains or strong winds for example. Biological soil crusts protect the outer layer and increase roughness, which is proved to help with soil stability.
- Carbon cycling
Carbon cycling is a crucial element for the development of al types of life. Biological soil crust uses respiration and photosynthesis to boost carbon cycling and promote the evolution of life in arid regions.
Pieces of land with biological crust can be used for a range of different purposes. Some of them are grazing, recreation and different types of plantations.