Small but Mighty: Biocrusts
Small but Mighty: Biocrusts
When we talk about grasslands, we tend to place a heavy focus on just the grass component and that is only a portion of what makes this ecosystem complete. If you look a little closer at the ground you may notice tiny little plants that stick up only a centimeter or two and creep along the ground. This is known as the biological crust or ‘living skin’ and they are formed with a combination of mosses, lichens, algae’s, fungi and numerous other soil organisms. This tiny, seemingly unimportant community has a significant impact on grasslands and their health.
This biocrust is formed over years and decades but it is extremely susceptible to disruption such as cultivation. If this biocrust is disrupted by cultivation, it may never come back and if it does it’s more of a modified community and will still take decades to reach that state. If a grassland is overgrazed, the biocrust community will decrease as well due to the extensive trampling by animals. Some disruption is good though in order to keep heterogeneity active on grassland landscapes. By having different plant species present it will increase the overall biodiversity of the grassland and the wildlife that can call it home.
The biocrust can play a vital role in protecting the soil from erosion. It acts as a barrier from the wind and rain that may cause pedestalling around individual plants or shearing of hillsides. It can also block the hot sun on summer days, decreasing the amount of water lost through evaporation. Water filtration can be increased in the presence of biocrusts because they can develop rough surfaces that hold the water longer on the soil surface. Although, there are some cases that depending on the dominant type of organisms, they will negatively impact water infiltration by swelling in the presence of moisture and not letting it reach the soil. The types of organisms that make up each biocrust will vary greatly between different ecosites such as sand or loamy sites.
Many of the organisms that make up the biocrusts are drought-resistant and this combined with the ability for them to protect the soil, increase water filtration and nutrient cycling, make it an incredibly valuable resource on grasslands. Soils take a long time to develop on grasslands and the last thing a landowner wants is patches of bare soil that will blow away in the next breeze. Having a natural barrier to protect what is already there sustains a healthier environment for other grasses, shrubs and trees to thrive in.
Due to the rough surface of the biocrust, they can also catch grass seeds to re-seed native species. Although, if the biocrust is primarily species like lichen and cyanobacteria it has been found that they can prevent establishment but some native species have tricks to get by this and have evolved to drill through the biocrust layer in order to germinate and establish. Due to this characteristic of some biocrusts, it can also prevent non-native species from taking over.
For such a small community of organisms, they play an important role in the health of our grasslands. So next time you’re walking through a pasture or hiking a trail through the prairies, take a moment and check out all the different plants and organisms that play a part in this ecosystem.
Author: Mindy Hockley-Anderson