Ecology and restoration of biological soil crusts (biocrusts)

Biological soil crusts (biocrusts) are the coolest thing that most people have never heard of. They are a soil surface assemblage of many different organisms including but not limited to cyanobacteria, fund, mosses and lichens in any combination. The defining characteristic is that they hold together the uppermost millimeters of mineral soil in a cohesive layer - a crust. You can find them throughout the world in places where sufficient light can reach the soil surface for these photosynthetic soils to operate. Because dense cover of plants shades out these communities, they are typically found in the dry and/or cold parts of the world where vascular plant cover is limited.

These organisms are desiccation tolerant. This means almost all of the water can evaporate out of their bodies, but they remain alive. Take a second to reflect on how AMAZING that is! When it does rain, they can rehydrate and are ready for action again. Check out the rehydration of these desiccation tolerant biocrust mosses in this video by Kyle Doherty.

Another of the most interesting things about them is their multi functionality. Since they hold soil particles together, they protect soils from erosion. Like plants, they fix and store carbon. Like most soil communities they also decompose organic matter and cycle nutrients. Biocrusts harbor N-fixing species too, and strongly influence the fate of rainfall by dictating infiltration and runoff rates. All of this function can be easily lost because soil disturbances can degrade them quickly, and their recovery after disturbance can be slow, at least in some ecosystems.

I have been studying these communities since the late 1990's as an undergraduate. At the time, it seemed like an important topic that too few people were actively working on. Since that time, biocrusts have taken me to various locations in the United States, Spain, and Australia and I have addressed topics as diverse as reproductive ecology, distribution, physiology, biodiversity, multi functionality and restoration of biocrusts. Their importance drew me to them, but they have been an endless well of fascination for me ever since.

Although I remain open to any and all research on biocrusts, the strongest theme in the lab right now is restoration. Re-establishment of biocrust communities is an essential step of recovering lost function, especially in the drylands of the world. We (myself, Kyle Doherty, Anita Antoninka, and soon, Kristina Young) are learning how to grow biocrust organisms, apply them in the field, and measure their benefits toward ecosystem recovery. We've got work going in the Colorado Plateau, Great Basin, Chihuahuan Desert, and soon the Mojave Desert too. Although in many of these regions crusts naturally recover slowly after disturbance, we are finding that slow growth is not "hard wired", in fact we can obtain substantial growth in only months for some of these organisms.

Growth of a cyanobacterial-moss biocrust over 4 months.

Some of the players in our artificial crusts.

No comments:

Post a Comment