XVI International Botanical Congess
Biological soil crusts are a physical aggregation of surface soil particles formed by the actions of cyanobacteria, algae, fungi, bacteria, lichens, and mosses. Soil crusts are especially prevalent in more arid regions of the world, where they can alter soil moisture and nutrients and affect germination and growth of plants. I studied the cyanobacteria, algae, and diatoms of soil crusts in a xeric Florida shrubland and their interactions with 4 co-occurring herbs. Soil crust microorganisms were heterogeneous over the landscape and correlated with soil moisture. Frequency and biomass of microorganisms decreased with site age and soil depth. Initial greenhouse studies have shown that seed germination is improved for 3 of the 4 herbs when crusts are present, but field studies suggest that soil moisture, site age, and shrub proximity modify the effects of crusts on germination.