Plant diversity increases in an urban wildland after four decades of unaided vegetation development in a post-industrial site

Abstract Spontaneous plant communities found in abandoned post-industrial landscapes develop in unique conditions which can create novel community assemblages. We examined changes in plant community composition and its relation to soil properties in an urban brownfield more than 40 years following site abandonment to better understand the community’s long-term trajectory. A former railyard and industrial area built on fill material, the study site includes four primary habitat types: grasslands, perennial forb assemblages, shrubland, and early successional forest. Plant species cover was measured in permanent plots in 2008 and 2016/17. In 2008, soil samples were collected and analyzed for a suite of properties. Species richness and Shannon diversity increased across the site from 2008 to 2016 (40 and 48 years post-abandonment) though increases in these parameters were highest in plots with lower metal concentrations. Evenness changed little in this time period. Percent cover of woody species increased in grassland and forb plots while percent cover of vines increased across all habitat types. Forb species tended to be associated with higher nutrient concentrations while woody species distribution was correlated with higher concentrations of heavy metals. The mitigation of soil stress, limitations in propagule availability, and loss of tree canopy cover following disturbances may have all played a role in influencing increases in diversity in this time period. Considering difficulties in comparing post-industrial abandoned landscapes to other anthropogenic and natural habitats, long-term study is needed to refine our understanding of community assembly in urban brownfields and better guide management practices.