A longitudinal roadside study of the New Hampshire alder root nodule microbiome.

Actinorhizal plants are pioneer plants that colonize harsh environments and have been used for land reclamation. Their ability to thrive under these harsh conditions is due to their symbiotic association with the nitrogen-fixing bacterium IMPORTANCE: Actinorhizal plants like alders are important ecologically and economically as pioneering plants. The symbiotic association with Frankia greatly accelerates the growth of the host plant and indirectly does the same for neighboring plants. Actinorhizal trees provide an excellent mechanism to restore disrupted environmental sites and have been used to reclaim land that has been used for strip-mines, gravel pits, and soil stabilization of other landscapes disturbed by the effects of erosion and water runoff. Actinorhizal plants are found on coastal lands around the estuaries, and some are proven to be salt tolerant. Elucidating the dynamics of microbial community structure of the alder root nodules will help our understanding of the ability of these pioneering plants to reclaim degraded lands and to survive in diverse harsh environments. The role that other members of actinorhizal plant root nodule plays may be important to that survival ability. This field study reports on the influence of soil variables, habitats, and seasons on the dynamics of the actinorhizal microbiome.