Maximum crown area equation for open-grown bur oak

Bur oak (Quercus macrocarpa Michx.) is a classic savanna species with a range that covers much of the eastern United States. Because savannas are an endangered habitat in North America, significant restoration efforts are in progress across much of the range of bur oak. For open sites being planted with bur oaks as well as fully stocked sites that are being thinned to create savanna conditions, an understanding of potential maximum crown area is of great utility. Between 2013 and 2015, 45 open-grown bur oaks ranging in size from 3.6 to 36.1 inches diameter at breast height (d.b.h.) were measured across central and southern Wisconsin. The equation Crown Area = 3.253DBH2.004 was used to predict crown area with an r2 of 0.93 (p < 0.001). This strong relationship has substantial utility for modeling crown cover to guide management of savanna restoration sites.