CYANOBACTERIA AND CYANOLICHENS - CAN THEY ENHANCE AVAILABILITY OF ESSENTIAL MINERALS FOR HIGHER-PLANTS

In both field and greenhouse studies, cyanobacteria and cyanolichens o f cold-temperate deserts often enhance growth and essential element up take by associated herbs. That effect is associated with better seedli ng establishment and larger seedlings. The following are possible mech anisms for these effects: (1) the microbiota concentrate essential ele ments in available forms in soil surface layers, (2) the microbial sur face covers are usually darker colored than the soil itself and produc e warmer soils during cool seasons when soil water is most available, (3) the gelatinous sheaths of several cyanobacterial genera common on alkaline deserts contain chelating compounds, and (4) conditions that favor persistent microbial growths on soil surfaces also favor mainten ance of larger populations of microorganisms that form mycorrhizal and /or rhizosheath associations with seed plants. There is evidence that associated animals may be nutritionally benefited by the enhanced mine ral content of forage plants growing in well-developed cyanobacterial crusts.