Biogeographia – The Journal of Integrative Biogeography

This study investigates how proximity and elevation relative to Interstate-495 highway (I-495) in Queens, New York, influence soil bacterial community structure. Twelve soil samples were collected across a 673,312-m² area with uniform sand, clay, and silt composition, spanning a gradient of increasing distance and elevation from roadside conditions (RC). Using 16S rRNA gene sequencing targeting the V3/V4 hypervariable regions, microbial diversity and composition were assessed across samples. Results revealed that soils closest to RC but at higher elevation exhibited reduced bacterial diversity and phylogenetic breadth, with dominance of Coxiella burnetii, Streptococcus spp., and Achromobacter. In contrast, the sample at the same elevation as the roadside (CC_I495_3) displayed the highest Shannon diversity (7.67), Faith’s Phylogenetic Diversity (27.14), and a more even taxonomic distribution, including rare and evolutionarily distinct taxa such as Myxococcus and Nitrospira. Notably, uncultured species were significantly more prevalent in this low-elevation RC-exposed sample. Of the 502 operational taxonomic units (OTUs) identified, 189 were unique to RC-exposed soils, 114 were exclusive to NO-RC soils, and 199 were shared across both groups. These findings suggest that both proximity and elevation modulate microbial community assembly.