Local and landscape drivers of predation services in urban gardens

Urban Farm DB summary

The influence of local, garden-scale factors (herbaceous and arboreal vegetation abundance and diversity, ground cover) and landscape-scale factors (landscape diversity and surrounding land use) on predation services was examined in 19 urban gardens on the California central coast. Sentinel pests — moth eggs and larvae and pea aphids — were placed on greenhouse-raised plants in open plots versus bagged, predator-exclosure plots. Predation rates were high, with 40% to 90% of prey items removed in open treatments. Predation services varied with local and landscape factors, but significant predictors differed by prey species: predation of eggs and aphids increased with vegetation complexity in gardens, while larval predation declined with vegetation complexity. Smaller gardens experienced higher predation, likely due to greater predator abundance, and several ground cover features influenced predation services. In contrast to patterns in rural agricultural landscapes, aphid predation declined as landscape diversity increased.