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).

Us

Between the years 1970-2000, urban areas have expanded worldwide into natural or agricultural lands with an area about the size of Belgium (Goldblatt et al, 2018).

The Lessons of a Hideous Forest

Arborist William Bryant Logan wrote in the New York Times (July 20, 2019) about the rewilding of New York's Fresh Kills landfill from a recent visit. He reports on the surprising plant and animal biodiversity and of Nature's ever-present healing abilities. Read about it at https://www.nytimes.com/2019/07/20/opinion/sunday/forest-garbage-trees.html?smtyp=cur&smid=tw-nytimesscience

Bird compositions are changing from bird feeding

A recently published paper by Plummer et al in Nature (Nature communities 10) reveals that in a forty year study, urban bird populations are changing to feeder-oriented birds. So the birds on seed bags is actually an urban bird checklist!

Overcultivation reduces biodiversity

A study of 85 urban gardens in Zurich analyzed management intensity and resulting soil macro and microfauna. The researchers found that high garden management intensity declined plant diversity and soil fauna.  

From: Direct and indirect effects of urban gardening on aboveground and belowground diversity influencing soil multifunctionality

Simon Tresch, 

David Frey, 

Renée-Claire Le Bayon, 

Paul Mäder, 

Bernhard Stehle, 

Andreas Fliessbach & 

Marco Moretti 

Scientific Reports volume 9, Article number: 9769 (2019)