St. Croix WMD |
Oak Savanna Restoration and Management
Oak savannas are one of the most endangered ecosystems in the world with less than 1/10 of one percent remaining. Oak savannas are a fire dependent community dominated by an overstory of oak trees and an understory of native grasses and forbs. In the District, numerous species of oaks, including burr, white, Hill's and black, are found in oak savannas.
Without fire to control succession, these communities are overrun with aggressive tree species such as maple, ash, buckthorn, Siberian elm and box elder that thrive in the open conditions in a savanna. Eventually, as the old oak trees die these savannas turn into forest and lose their characteristic grass/forb dominated understory. With the suppression of wildfire and human development of the landscape, oak savannas are rapidly disappearing. Restoration of oak savannas is very labor intensive and often entails dramatic changes to the landscape.
The process of restoring each savanna differs based on the number and species of oak trees present, the long term viability of burning the unit and the degree of invasion by invasive species such as buckthorn, Siberian elm and honeysuckle. Although initial restoration of savannas will involve removal of non-oak tree species and some grass/forb planting, complete restoration through repeated burning and control of brush and invasives may take 30-40 years before a more natural fire regime of burning every 8-15 years can be used.
