How Pittsburgh's tree canopy affects neighborhood surface temperature

Written by Ethan Magoc on .

Tree coverage is sparse on parts of Pennsylvania Avenue in Central Northside and Manchester, which are among the city's hottest neighborhoods, according to a 2010 land surface thermal image. (Ethan Magoc/Post-Gazette)

Which are Pittsburgh's hottest, least tree-covered neighborhoods?

It's that time of summer in Pittsburgh when the sun and humidity make everything generally unpleasant by noon.

The hotter temperatures can be more pronounced in parts of the city where little shade coverage is available, but exactly how much of a difference does a tree canopy make?

Tree Pittsburgh, an environmental advocacy group, enlisted a University of Vermont researcher in 2010 to try to find the answer. Using a satellite, the researcher created a surface thermal image. The one-day snapshot is not a direct correlation to how many trees each neighborhood does or does not have, but it is illustrative of what Tree Pittsburgh calls "urban heat islands."

"It seems to be more correlated with where there are impervious surfaces," said Jen Kullgren, a community forester with Tree Pittsburgh. "Large scale rooftops, dark rooftops, things like that — things that would retain heat in that area."

Many of the North Side neighborhoods, such as Manchester, are among the city's hottest, as is South Side Flats.

A landsat thermal image from Sept. 2, 2010. Click for a larger version. (Courtesy of Tree Pittsburgh)

There has not been a similar image captured since 2010, but the City of Pittsburgh is updating a tree inventory and will finish by summer's end.

City forester Lisa Ceoffe is creating the inventory with the Western Pennsylvania Conservancy. It's the city's first effort since 2005 to discern a precise count of how many trees it owns in each neighborhood.

And Ceoffe said it's not just a couple of interns driving around, counting trees.

"You need to have a lot of knowledge," she said. "These are skilled arborists who have to be very familiar with tree species and how to look at a tree."

She said 22,000 city trees have been planted through TreeVitalize since the 2005 count. That 2005 inventory actually indicates Manchester and Central Northside have the one of the highest counts of city-owned trees per neighborhood acre.

(This obviously does not include trees your neighbors own.)

Neighborhood Tree count per acre Acres Tree count
Friendship 3.60 68.297 246
Manchester 3.40 179.566 610
Central Northside 3.36 166.475 559
Shadyside 2.70 592.104 1601
Allegheny West 2.52 90.841 229

More than one Pittsburgh neighborhood name contains a nod to trees or, more generally, green space: Greenfield, Oakland, Oakwood, Homewood and Shadyside (and as Brandon points out below, also Beechview, Bloomfield, Glen Hazel, Hazelwood, Fairywood, etc)Glen Hazel, Hazelwood, Fairywood, Beechview, Bloomfield.

Which neighborhood do you think is the city's warmest or least leafy? Let us know in the comments below.

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