Q. How does asphalt laid down close to trees affect their growth?
Paving too close to a tree is a common problem along roadways and especially in parking lots. There are four reasons that paving in very close proximity to trees can damage them.
- Paving over the root system of an existing tree restricts its ability to exchange gases with the atmosphere, a critical dimension of tree root health.
- Paving prevents rainfall from entering the soil and reaching the roots, further reducing their viability.
- If the pavement was laid in a conventional manner, there was an excavation of 6-8 inches to provide space for a sub-base, binder course, and finish asphalt. There may be far fewer roots left than there once were.
- Heated asphalt in contact with the trunk of a tree may damage its cambium (growth layer) and the year’s annual ring in a manner that will restrict conduction to and from the remaining roots.
Some trees are more fragile than others. London plane trees, for example, are darn near impossible to kill.
For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service