[katieHaylor (OP)]

Justin asks:

Could having trees in the parking lot make the area healthier and safer?

What do you think?

[timey]

Any planting of trees is good for the environment providing that thought is put into the type of tree one is planting in relation to the terrain and it's usage.  For instance many millions of trees were planted (historically in the 1960's+) in Scotland under grant incentives.  However the planting was mainly conducted with Sitka Spruce, a fast growing non-indigenous conifer.  Although plantations are usually sited on land which is too poor for agriculture, the harvesting of these cash crops leaves huge ruts in this higher land, and topsoil is eroded from the site leaving the land damaged and unable to recover it's natural state, adversely affecting wildlife and the natural ecosystem.

Trees in a car park are a good idea.  Shade will stop cars becoming hot in the summer months.  However, lime trees and trees that bear any type of fruit are not good to park your car under at certain times of the year.  Lime trees release a sticky sap that is hard to clean off, and berries or their juice and the related bird droppings from the flocks of birds that dine on them can be annoying, while larger falling fruits may leave dents.

[evan_au]

Evaporative cooling from trees reduces the heat island effect of bare tar or concrete.
But bird poop landing on cars from perching birds is a nuisance.

Ensuring that the trees have adequate water supply is a problem, as most water hits the hard pavement of the carpark and runs off immediately into streams, causing flooding. Ideally, the rain water would be absorbed by the soil, and would water the trees - but then we are back to the era of dirt roads and horses...

Perhaps the root cause of this problem is that 90% of cars spend 90% of their time sitting idle and taking up valuable space and resources while they rapidly depreciate into piles of rust...  This causes us to pave over large areas of otherwise useful land and chop down all the trees?

PS: All figures in this post are POA (Plucked Out of the Air).

[alancalverd]

The London Plane tree is apparently exceptionally good at absorbing airborne toxins as well as CO2, and has replaced the traditional Poplar plantings along many French roads

Rain runoff shouldn't be a problem if the area is landscaped so that the first run is into the tree root area - you end up with less overall runoff from the site. Part of my garden is a natural car park where the trees reduce immediate local rainfall under the canopy, soak up what rain does fall, and reinforce the grass with their near-surface roots. The surface is as good as concrete all year round, and much prettier.