Community Analyses of Urban and Suburban Forested Natural Areas in Shelby County, Tennessee, Reveal Old-Growth Attributes

European colonization of eastern North America resulted in widespread loss of old-growth eastern deciduous forest, altering native plant and animal biodiversity. Though recent studies have revealed remnant old-growth forests, it remains uncertain how widespread forests with old growth characteristics are throughout the southeastern United States. This is especially true near urban centers where historical disturbance was likely most pronounced. Yet, small patches of forest with old growth characteristics persist as urban or suburban forested natural areas where they are important reservoirs of biodiversity and provide crucial ecosystem services. Here, we investigate several upland deciduous forest communities in Shelby County, Tennessee, to assess whether urban and suburban forested natural areas exhibit species assemblage and structural features consistent with commonly-accepted criteria for old-growth forest, and how they may have been shaped by diverse land use histories across an urban to suburban gradient. We found community composition broadly similar between urban and suburban forested natural areas, but also significant differences in species assemblage based on tree densities and basal areas, likely due to unique land use and disturbance histories. Forests also meet some, but not all, commonly employed criteria for western and mixed mesophytic old-growth forest, including individual tree ages >200 years, consistent with ongoing successional trajectories toward old-growth forest. Nevertheless, the urban and suburban forested natural areas of southwest Tennessee harbor important plant biodiversity in a region that has experienced intensive post-colonial anthropogenic disturbance and likely warrant continued thoughtful management and restoration to attain “new” old-growth status.