Urban trees have a tough row to hoe! Imagine, if you will, living in starvation for most of your life but expected to look your best at all times. That is certainly not the life for me!
This is to what expect from our urban trees. We have codes to go by when building on commercial properties which require a certain number of trees. We have historical districts and home owners associations that require certain trees be left alone or tree fo tree replacements. NC State, along with several other Land Grant Colleges, have tons of research on what species do well and which perform poorly in this situation. However, you always see red maples, sometimes exclusively planted in these areas and they perform horribly.
By the way, a quick visit to the NC Extension Gardener Plant Toolbox, will quickly tell you that this is not the place for this tree. Red Maples (Acer rubrum) are an understory tree that like the edge of a swamp. For some reason, they are one of the most planted trees along our streets. Even in the historic district of Washington, you can find them on nearly every street.
So what are some of the issues that cause these trees to fail? One of the biggest issues is impermeable surfaces. Impermeable surfaces are those that do not allow water to move through them. Think of your house, sidewalks, streets, concrete driveways, and out buildings. None of these are designed to allow the transfer of water through the surface. If the roots of our trees are under that surface, how do they get water? If there isn’t any water, how do they get their nutrition? All of the nutrients that a tree takes up from the soil are dissolved in soil water solution, no water = no nutrients!
If you follow my articles or have taken a class with me, you can probably guess my next issue, right plant, right place. All too often we choose the wrong plant for the space that we have for it to fit in. We will put plants that love shade in a place where they are receiving direct sun. We may use the example of a red maple here as well. Here is a tree that enjoys being an understory tree, growing in mostly shade on the edge of a swamp and we put it into direct sun in between a sidewalk and a curb. We expect to prosper in an area where it is suffocating to say the least. Many of these trees are planted in a strip that is only three feet wide!