Adding fill also excludes oxygen. Sometimes this kind of damage will kill a tree outright within a few years, but more commonly there will be a prolonged decline, with secondary, opportunistic agents often getting the blame. It doesn t take a construction project to cause lethal damage to tree roots. Repeated driving over the roots, especially when the soil is wet, will cause severe compaction. And a clay or silt soil is much more prone to compaction than a sandy soil.
Trees have complex ways of fending off disease, insects, and decay.
For those defense systems to work properly, a strong root system is needed. A tree with damaged roots will not be able to manufacture and transport decay resistant chemicals to a wound site, for example, and will be subject to more extensive decay. The same goes for insect damage, below. Many times, the problem is not the problem, if you know what I mean. Let s say you glance out the window and see, to your dismay, wood chips the size of baseballs raining down from your favorite white pine.