Regeneration dynamics in old-growth urban forest gaps.
Urban forests are critical for biodiversity conservation and offer a broad range of benefits to society, including provisioning, regulating, and cultural components of ecosystem services. Urban forests warrant more ecological attention in order to ensure the sustainability of these important natural areas, especially as they are often faced with unique challenges arising from habitat isolation, high densities of invasive species, and heat and pollution stress. The present study sought to document gap dynamics and species recruitment in an old-growth urban forest in the Southeast United States in order to address concerns that gaps in the forest are not regenerating. Seeds were collected, and seedlings were tagged and monitored for a year in gaps and paired closed forest plots. Seedlings had higher growth and survival rates in gaps compared to the closed forest. Gap and closed forest seed and seedling communities were similar in species composition, but there were differences in the composition of species in seed and seedling communities, although seedling and adult communities were more similar. Seed and establishment limitation were both detected in our study plots, and the two were negatively related. Overall, our gaps were relatively young and appeared to be benefiting from the active management of invasive species. Urban forest managers face multiple challenges in stewarding their forests, including monitoring the composition of the recruiting communities and carefully studying the impacts of invasive species on forest regeneration.