Riparian corridors are recognized for their high plant biodiversity.  One contributing factor to recent biodiversity decline in these regions is invasion by exotic species, although it is not clear why native riparian vegetation is sensitive to invasion.  Soil microbial communities can play an important role in colonization of plant species and, thus, changes in this community may also impact plant diversity, including success of invasives.  In this study, two riparian plants, Russian olive (Elaeagnus angustifolia), an invasive found along the Rio Grande, and hazel alder (Alnus serrulata), a native to southeastern wetlands, were examined to elucidate roles that soil bacterial communities play in determining plant-specific, root-rhizosphere colonization.  Examination of soil bacterial community composition associated with both plants in field and experimental studies was accomplished by terminal restriction fragment length polymorphisms (TRFLP).  Our field studies showed substantial differences in bacterial communities associated with bulk soils and rhizospheres of A. serrulata and E. angustifolia.  Experimental studies suggested bacterial communities from bulk soil in Russian olive stands may outcompete bacterial communities associated with soils around native, wetland plants.  Therefore, variation in the rhizosphere bacterial community can be partly attributed to soil characteristics, as well as differences in the bulk soil bacterial community.