Parking lot islands are probably the most inhospitable place for trees to grow. Reflected heat, small soil volumes and vehicle emissions can impact their health. The life expectancy of parking lot trees is 7 - 10 years. Some defy odds and flourish despite the challenges.

Roots are generally deflected by the curbing or sidewalks and remain in the planting area which can contribute to an unstable tree. Some roots may escape the planting 'pits' and grow under the asphalt, especially if the soil isn't too compacted. The roots may grow at a depth where the increased temperature of the asphalt doesn't affect them.

In our clay soils, water moves laterally through the soil including soil under asphalt. Eventually the asphalt over the roots may crack creating the need for parking lot repairs.

New 'structural soils' and porous concrete are availiable for parking lot planting areas or paved areas which allow tree roots to flourish. However, it can be cost prohibitive for many construction projects.

Parking lot shade I most enjoy are these!

Here is a link that might be useful: parking lot shade