As urban land continues to expand, there is increasing interest in understanding ways that urban ecosystems can improve quality of life, provide environmental services and reduce environmental impacts of human activities. However historic and current human activities pose many unique challenges to establishing and maintaining urban green space. Among these challenges, trace metal contaminated anthropogenic soils can significantly alter the development, productivity, and resilience of plant communities. An understanding of the potentials and limitations of anthropogenic soils is critical to maximizing the benefits which can be provided by urban ecosystems. In this study we compare plant community assemblage trajectory with temporal changes in soil trace metal concentration in an urban brownfield in Jersey City, New Jersey, USA. Total recoverable soil metal concentrations of As, Cr, Cu, Pb, and Zn were measured in soil samples collected in 1995, 2005, and 2015 at eight forested plots in the study site. Vegetation assemblage trajectory was based on analysis of aerial photography and ground measurements of species diversity.
Results/Conclusions
Analysis of soil metal concentrations in the A horizon suggest that overall Cu, Pb, and Zn concentrations in these plots have been consistent over the course of 20 years. Several plots showed a pattern of increasing As and Cr concentrations. In the plot with highest total metal concentrations, Pb and Zn concentrations decreased with time. Between 2005 and 2015, pH exhibited little variation within each plot suggesting pH-based bioavailability of heavy metals has been consistent in this time period. From 1995 to 2015, several of the study plots underwent changes in plant community guild, shifting from meadow or shrubland to early successional hardwood forest. Prior research at the site found significant correlations between soil metal concentration and vegetation community diversity, assemblage trajectory, and net primary productivity. These data appear to show that metal contamination in urban soils exerts a strong influence as an abiotic filter during establishment however, as the assemblages develops the effect of this filter may decrease.