Crown encroachment on southern live oaks in suburban settings: tree status and homeowner concerns

"We recorded the status of the crowns of 50 southern live oaks (Quercus virginiana) in each of four suburban neighborhoods in Gainesville, Florida, U.S. We focused on the extent to which the crowns of formerly open-grown live oaks were encroached on by other trees. Once the crowns of live oak trees develop their characteristic open-grown form, they are very susceptible to trees overtopping them from the side or even piercing up through their crowns from below. Unfortunately, severely shaded mature live oaks seldom recover, even if the encroaching tree crowns are removed. Few (7.5%) of the live oaks surveyed were not crowded. On the basis of stem growth rates and stem-crown diameter relations of the principal encroaching species, we predict that unless the encroached live oaks are provided with space to grow, approximately half of them will succumb to crowding within the next 5 to 13 years, depending on the neighborhood. Although the 23 homeowners surveyed valued their live oaks highly (mean assigned value $6,887), only about half said that they plan to provide them growing room even after they were informed of the encroachment threat." [Abstract]