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| Urban green spaces provide ecosystem services to city residents, but their management is hindered by a poor under-
standing of their ecology. We examined a novel ecosystem service relevant to urban public health and esthetics: the
consumption of littered food waste by arthropods. Theory and data from natural systems suggest that the magnitude
and resilience of this service should increase with biological diversity. We measured food removal by presenting
known quantities of cookies, potato chips, and hot dogs in street medians (24 sites) and parks (21 sites) in New York
City, USA. At the same sites, we assessed ground-arthropod diversity and abiotic conditions, including history of
flooding during Hurricane Sandy 7 months prior to the study. Arthropod diversity was greater in parks (on average
11 hexapod families and 4.7 ant species per site), than in medians (nine hexapod families and 2.7 ant species per site).
However, counter to our diversity-based prediction, arthropods in medians removed 2–3 times more food per day
than did those in parks. We detected no effect of flooding (at 19 sites) on this service. Instead, greater food removal
was associated with the presence of the introduced pavement ant (Tetramorium sp. E) and with hotter, drier condi-
tions that may have increased arthropod metabolism. When vertebrates also had access to food, more was removed,
indicating that arthropods and vertebrates compete for littered food. We estimate that arthropods alone could remove
4–6.5 kg of food per year in a single street median, reducing its availability to less desirable fauna such as rats. Our
results suggest that species identity and habitat may be more relevant than diversity for predicting urban ecosystem
services. Even small green spaces such as street medians provide ecosystem services that may complement those of
larger habitat patches across the urban landscape. | |
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