This is Scientific Americans 60 Second Science. I'm Jason Goldman.

Trees in cities do measurable good for biodiversity and for human health.

They scrub pollution from the air. They provide habitat for

wildlife. They make streets look nicer and they even reduce stress and have been

linked to reductions in crime.

Back in 2015, a group of Toronto-based researchers discovered that planting just 11 more trees

per city block could reduce heart-related conditions by the same amount as if everybody

living on that block became a year and a half younger.

But in Detroit, between 2011 and 2014, a quarter of eligible homeowners turned down an offer

from a local non-profit for free street trees.

Ironic, considering Detroit's nickname was once the city of trees.

It was actually over 1800 trees that were rejected out of an eligible 7,425.

So it was a big enough issue at that point where it warranted further investigation.

Forestry researcher Christine Carmichael, who did the research at Michigan State and has since moved to the University of Vermont.

The non-profit created an education campaign to get more residents to accept the free trees.

The assumption being that if people had all the facts, they'd be more likely to take the trees.

But when Carmichael talked to residents, she found that they understood the benefits of trees.

Their unease was about trust.

Basically what I found was that opposition in Detroit to tree planting among some of these

residents resulted primarily from negative past experiences with street

trees particularly in low-income neighborhoods that were grappling with blight from vacant properties, which created an additional burden of care for their neighborhood.

In the last half century or so, more than half a million Detroit trees died from disease and neglect.

...