The effect of rhizospheric communities on nutrient availability during the colonization, and growth phase of Lupinus diffusus

Because legumes are critical to reclamation and restoration of nutrient-poor sites, we need to understand the mechanisms involved in their establishment.  Of key importance is defining and identifying what abiotic and biotic factors inhibit or facilitate colonization and growth over time.  The aim of this study was to determine the effect of rhizospheric microbial communities on nutrient acquisition by Lupinus diffusus, a colonizer of recently disturbed sites.  In addition, the study attempted to verify how seasonal trends affect microbial communities and nutrient availability. We found that Lupinus diffusus forms nodules in the early phase of its growth, but nodules are rarely present in older individuals.  Low enrichment culture based methods confirmed marked shifts in rhizospheric microbial communities over time.  We also observed bacterial inhibition of fungi, which may indicate competition between free-living bacteria and fungal communities within the rhizosphere. These results indicate that complex interactions among legumes, rhizospheric bacteria, and fungi will affect restoration success.