Why Are Trees Removed?
The City of Toledo makes every effort to only remove trees when absolutely necessary. Trees in the immediate vicinity to a construction site are sometimes removed because they will often be killed during the construction process, or damaged to the point where they will die in the next few years.
Tree roots grow where they are able to absorb water, oxygen, and minerals from the soil. The biggest supply of these materials is in the top layers of soil. Because of this, most of a tree's roots are located in the top 24 inches of soil. For a typical road reconstruction, crews must dig a minimum of 30 inches deep. This means that in a typical road reconstruction, any tree adjacent to the road will lose the vast majority of their roots on one side. Alternatively, resurfacing a roadway typically doesn't require any excavation, and will often not impact trees.
When a tree loses that much of its root system, its ability to absorb nutrients from the soil is greatly impacted. Because trees can store a large amount of nutrients in its remaining roots, the tree often will not die immediately. However, in the few years after construction, the chance that a tree that was heavily damaged during the project will die is very high. Additionally, a tree's roots provide the above ground portion of the tree stability. With almost half of its roots missing on one side, the impacted tree becomes a dangerous fall hazard.
Another factor that can affect the trees is a change in the soil conditions. During a reconstruction, underdrains are placed below ground along the length of the road on each side. These drains absorb water from the surrounding soil to keep the base of the road dry. This greatly increases the longevity of the road, but also robs the trees of some of their water supply. Many mature trees will die as a result to this change in their habitat. Also during construction, the soil is compacted by vehicles and equipment. This too limits the amount of water or oxygen that the soil is able to store and subsequently is available to the trees.
During the planning stages of a project, trees are individually evaluated by experts from the City of Toledo's Forestry Division. Every effort to save trees is made, and trees are only removed if the Forestry expert deems it absolutely necessary.
In the picture below, the tree's roots remain after the tree has been removed prior to construction. You can see how the roots are heavily damaged. This picture was taken after underdrains were placed and backfilled.