Gentrification drives patterns of alpha and beta diversity in cities.

While there is increasing recognition that social processes in cities like gentrification have ecological consequences, we lack nuanced understanding of the ways gentrification affects urban biodiversity. We analyzed a large camera trap dataset of mammals (>500 g) to evaluate how gentrification impacts species richness and community composition across 23 US cities. After controlling for the negative effect of impervious cover, gentrified parts of cities had the highest mammal species richness. Change in community composition was associated with gentrification in a few cities, which were mostly located along the West Coast. At the species level, roughly half (11 of 21 mammals) had higher occupancy in gentrified parts of a city, especially when impervious cover was low. Our results indicate that the impacts of gentrification extend to nonhuman animals, which provides further evidence that some aspects of nature in cities, such as wildlife, are chronically inaccessible to marginalized human populations.

Silky dogwood (Swida amomum) seed dispersal by freshwater turtles.

PREMISE: Effective seed dispersal is essential to the success of plant species. Swida amomum (silky dogwood) has a seed-dispersal syndrome characteristic of autumn-ripening shrubs with fleshy fruits; attached fruits are ingested and defecated by birds, while fallen fruits are consumed by ground-foraging birds and mammals. METHODS: We documented that fallen fruits of this shrub were consumed by two aquatic turtle species (eastern painted turtle [Chrysemys picta] and red-eared slider [Trachemys scripta]) and that their seeds were defecated. We compared germination success (percentage of seeds germinated) of defecated seeds, seeds collected from a pond surface, and seeds removed from shrubs. RESULTS: While four seed species were identified in fecal samples, seeds of S. amomum were the most frequent (93%) among samples and the most numerous (106 seeds) in any sample. Average proportion of fecal seeds germinated (85.99%) exceeded that of seeds from the pond surface (82.76%) and from shrubs (60.24%), albeit the difference in germination success was insignificant. When analyzed using fecal samples from painted turtles only, the difference in germination success between fecal seeds and those collected from pond or shrub became significant. CONCLUSIONS: Our findings represent the first report of S. amomum seeds being dispersed by turtle gut passage and suggest aquatic turtles could be an important part of a secondary seed dispersal process influencing woody plant community composition in temperate wetland ecosystems.