Perspectives in Urban Ecology

(modified from Wu, 2008)

Diversified Management Expands Insect Biodiversity

Leston and Koper published in Journal of Urban Ecology (2019) their findings on their study of altering mowing regimes in urban rights-of-ways and their impacts on insect populations. They concluded that “to increase taller butterfly resources while still controlling weeds with urbn ROWs, we recommend reducing management frequency within the interior ROWs while maintaining frequent management along ROW borders that are adjacent to infrastructure.” This would reinforce landscape management recommendations of ‘cues to care’ on the outer edges to improve edge aesthetics of successional landscape approaches as well.

From ditches to bioswales

Zoe Myers, research associate at the University of Western Australian University, makes a compelling argument in her article "More than just drains: recreating living streams through the suburbs" that urban waterways deserve more than closely clipped lawns and ruderal weeds. Her research focuses on the benefits of converting traditional waterway management types to living stream corridors. She considers that this vast network of functional drainage systems could be opened to public use as a riparian park. Myers mentions that converting to bioswales would reduce urban heat islands, increase biodiversity, maximize aesthetics, and increase property values. Read more about it on The Conversation website at https://theconversation.com/more-than-just-drains-recreating-living-streams-through-the-suburbs-83345

The enemies hypothesis

The enemies hypothesis holds that predatory insects are more effective at controlling pests than mechanical or chemical control methods (Russell 1989). Parsons and Frank (2019) found evidence recently that by not including environments for predators around urban trees, pests can get out of control. They studied several hundred crape myrtle trees on the NC State campus and the types of environments that are around the trees, and found a positive correlation between crape myrtle pests and impervious cover (hardscape) within 100 meters of the trees. Diverse environments provide more opportunity for diverse beneficial controls.

Russell. 1990. Enemies Hypothesis: A review of the effect of vegetational diversity on predatory insects. Environmental Entomology 18(4).

Parsons, S. and Frank S. 2019. Urban tree pests and natural enemies respond to habitat at different spatial scales. Journal of Urban Ecology 5(1).