In the dry regions of the world, the soil surface is covered by biological soil crusts which prevent erosion, create and maintain soil fertility, and influence where water moves and is retained on the landscape. Biological soil crusts can be thought of as a large 'package' of ecosystem function that is easily lost due to widespread surface disturbances. Previous studies indicate that greater availability of micronutrients in the soils may promote recovery of degraded soil crusts. To test this hypothesis, two experiments will be conducted: one focusing on a key crust lichen species grown in a greenhouse, the other focusing on the whole crust community in the field. Response of crust organisms will be monitored following various fertilizer additions, including manipulations of the micronutrients Zn and Mn. A new biochemical technique involving fatty acids will be developed to measure the status of biological soil crusts. Finally, five existing large-scale datasets will be examined using a statistical modeling approach to test the hypothesis that micronutrients limit biological soil crusts in multiple arid regions of North America.
Desertification adversely impacts ~20% of the Earth's population, and new tools to combat it are desperately needed. Healthy soils are the foundation of terrestrial ecosystems. It is hoped that by finding ways to promote recovery of biological soil crusts, we can restore function to degraded arid ecosystems and find ways to slow desertification.
