Predictive Open-grown Crown Width Equations for Three Oak Species Planted in a Southern Urban Locale

Development of DBH/crown models from i-Tree Eco data on the Auburn University Campus.

"Models that predict ecosystem services in urban areas are useful tools to urban forest managers. Predictive open-grown crown width equations were developed for three oak species common in urban forests in the southern United States. Tree crown form is an important component of these equations; however, there are few predictive equations available for urban, open-grown trees. The species used were Quercus lyrata Walt. (overcup oak), Quercus nuttallii Palmer (Nuttall oak), and Quercus phellos L. (willow oak). The study authors believe that these are the first predictive open-grown crown width equations developed for these species in the southern U.S. Diameter at breast height (DBH) (independent variable), DBH2 (independent variable), and average crown width (dependent variable) data were used to create the predictive crown width equations and yielded R2 values of 0.96, 0.94, and 0.91 for overcup, Nuttall, and willow oaks, respectively. These equations can aid urban landscape and utility planners by providing a means to predict crown dimensions at varying trunk diameters. Field time could also be minimized by reducing the need to measure crown width and with time, these equations could be used to validate species specific equations (e.g., leaf biomass) for these and other southern urban-planted tree species." [Abstract]