Over the last two years we have transformed the Grady Tract landscape during a major restoration project—one of the largest, if not the largest, in Arboretum history. Our main goals were to remove invasive shrub species and restore the structure of the savanna ecosystem on nearly a third of the 203-acre Grady Tract. In March, we closed the books on the latest phase of work conducted by Arboretum staff, private contractors, and volunteers, with support from a Dane County Partners for Recreation and Conservation (PARC) grant.
Perhaps the biggest ecological impact came from forestry mowing approximately 60 acres of buckthorn, honeysuckle, and other invasive shrubs and small trees during the winters of 2014–15 and 2016–17 in the northern end of the Southwest Grady Savanna, the western part of the Kettle Hole Forest, and the Grady Knolls Forest. Clearing the brush revealed a rolling topography and ancient oak trees—including a 48-inch-diameter bur oak behemoth—that had been hidden for years. Sunlight that was previously blocked by tree and shrub canopy now reaches the ground and benefits numerous native wildflower species such as shooting star and wild bergamot.
The removal of many larger trees, including approximately 4 acres of pines, was another major phase in the project, which brought the density and composition of the remaining trees closer to the oak savanna that would have been present historically and more sunlight to the native savanna plant species that have been shaded out for so long. The trunks and branches from cleared trees have been repurposed into lumber, firewood, wood chips, and compost for use by the Arboretum and businesses in the Madison area.
Since fall 2015 we have conducted seven prescribed fires on the Grady Tract in units that had been forestry mowed. Prescribed fires reduce woody debris left over from mowing, top-kill resprouts and seedlings of invasive brush, and stimulate native plant growth. The fires also help prepare the areas for seeding by removing leaves and other plant material that have built up over the years. We purchased native plant seed with money from the PARC grant and have also harvested seed from the Arboretum. We have begun seeding in the Grady Tract already and will continue seeding this spring to help the native plant species re-establish populations.
We have also begun other ongoing tasks, including further clean-up of the site; managing invasive species like garlic mustard through pulling and herbicide application; and managing invasive tree and shrub resprouts and seedlings with additional mowing or cutting and herbicide application. As we work on these tasks in the coming years, we will also be carefully planning the next phase of restoration for this wonderful savanna site.
We’ve already seen a positive response to our restoration work from several non-plant species as well. While pulling and treating garlic mustard in April, our land care staff came across an American woodcock nest in one of the forestry mowed areas. We are always happy to see woodcock successfully nesting in the Arboretum as they are considered to be an “umbrella species,” meaning that the diverse habitat they require will benefit many other species as well. Several days after coming across the nest, the staff found the eggs had hatched!
We would like to thank Dane County for the two PARC grants awarded to support our restoration work at the Grady Tract, the first in 2011 and the second in 2014, as well as the contractors we partnered with: Cardno, Boley Tree and Landscape Care, and Quercus Land Stewardship Services. Many volunteers have also provided invaluable help to our staff and we thank them for their time, effort, and dedication to the Arboretum.
—Michael Hansen, Arboretum land care manager