I sit around thinking about this stuff (help me!), but when I think about all the parking lots and "recovery zones" on NCDOT roads I keep coming back to trees.
On a micro scale, establishing a tree canopy, particularly in summer, makes a huge difference in perception, aesthetics, and some difference in ozone formation. (Ozone needs both heat and sunlight as a catalyst in its creation).
The animosity between cars and trees is a huge untold story. Even had a DOT engineer once say, "Trees kill people!"
So the tree jumped out in front of the car? Ok, dude. Whatever. Speed also kills people much more definitively, and studies show that when you create a "sense of enclosure" for the driver they tend to slow down anyway out of the basic psychology of feeling like they have less space (http://www.fhwa.dot.gov/environment/sidewalk2/sidewalks209.htm Figure 9-7).
On a micro scale, establishing a tree canopy, particularly in summer, makes a huge difference in perception, aesthetics, and some difference in ozone formation. (Ozone needs both heat and sunlight as a catalyst in its creation).
The animosity between cars and trees is a huge untold story. Even had a DOT engineer once say, "Trees kill people!"
So the tree jumped out in front of the car? Ok, dude. Whatever. Speed also kills people much more definitively, and studies show that when you create a "sense of enclosure" for the driver they tend to slow down anyway out of the basic psychology of feeling like they have less space (http://www.fhwa.dot.gov/environment/sidewalk2/sidewalks209.htm Figure 9-7).
Midland Road between Pinehurst and Southern Pines is a great example of a truly beautiful road the NCDOT has been unhappy with for many years. Hats off to Tim Johnson, the Division Engineer there who has a pretty balanced view of how to work with it.
Parking lots are trickier, with the soil compaction from the weight of the cars creating problems for the trees and stunting growth. Davis and Sacramento California have development ordinances that try and approve plans based on canopy coverage of parking lots. The predicted canopy far underperformed the original plans for a specimen tree due to the distress for the tree. (Pdf link http://www.fs.fed.us/ccrc/topics/urban-forests/docs/parklotarticle.pdf)
Still, in the American South wouldn't we all like a shady parking spot in the summer? Add a quarter percent to your retail margin, mister big box. Totally worth it to have you pay for the soil engineering and have the shade.
Parking lots are trickier, with the soil compaction from the weight of the cars creating problems for the trees and stunting growth. Davis and Sacramento California have development ordinances that try and approve plans based on canopy coverage of parking lots. The predicted canopy far underperformed the original plans for a specimen tree due to the distress for the tree. (Pdf link http://www.fs.fed.us/ccrc/topics/urban-forests/docs/parklotarticle.pdf)
Still, in the American South wouldn't we all like a shady parking spot in the summer? Add a quarter percent to your retail margin, mister big box. Totally worth it to have you pay for the soil engineering and have the shade.
There is a water quality argument in here too--the canopy dissipates some of the speed of falling rain (slowing runoff), and reduces the temperatures of the surfaces the rain will fall on. This means less hot water suddenly hitting our surface waters at once because a) there is less of it all at once, and b) it's cooler.
I won't get into carbon sequestration arguments. Regulating tree cutting on private property is a whole post unto itself, though I will throw out a teaser from a former Durham City/County Planning Director, "Is the only way I can save trees in this place to build apartments?" More on that later.
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