Construction at Dirksen Nature Park
Construction has been completed on a new oak savanna overlook and wetland boardwalk at Dirksen Nature Park.
- The oak savanna overlook provides seating to view wildlife and to enjoy the establishing prairie restoration. Hidden around the overlook will be bronze depictions of different animals that live in Oregon’s oak savannas.
- A wetland boardwalk reaches into a stunning forested wetland hidden in the center of the nature park. Although the site is dry during summer months, winter brings a wet bayou-like setting where tall trees reflect in the water below. The boardwalk allows park visitors to get a close-up look at the trees and to enjoy this unusual setting, all without getting wet!
Camas at Dirksen Nature Park
Camas is a culturally important plant for northwest native tribes and is a beautiful oak savannah flower. Over 30,000 Camas bulbs were planted in Dirksen Nature Park in 2015 and bloomed for the first time in 2017. In addition, restoration specialists were caught by surprise when a large bloom of native bulbs emerged that were lying dormant and had been out-competed by non-native pasture grass.
Oak Savanna Restoration Project
Throughout the summer, the city’s contractor will clear areas around native oak trees and will remove/spray invasive trees and other non-native vegetation. Later in the year, native plants will be installed.
Dirksen Nature Park contains seven distinct Northwest ecosystems. They include Oak Savanna, Forested Wetland, Coniferous Forest, Mixed Deciduous Forest, Ash Forest Riparian Forest, Emergent Wetland, Scrub Shrub Wetland
Environmental Benefits of the Restoration Project
- Less than 2 percent of historic oak savanna habitat remains in the Willamette Valley. Restoring this remnant oak savanna will provide an opportunity for park visitors to view this important historic landscape.
- Thinning allows mature oaks to expand their crowns and produce more acorns, which provide food for wildlife. More tree cavities are formed in oaks with larger crowns. The cavities serve as homes for squirrels, birds and insects.
- This project will restore habitat for wildlife species like the western gray squirrel, white-breasted nuthatch and the acorn woodpecker. All use the grasslands and oaks of the savanna for food, cover and nesting.
- Thinning the savanna increases light to the forest floor, increasing growth of native flowering plants and benefitting pollinators like native bees and butterflies.
Educational Benefits of the Project
Tigard partnered with Tualatin Riverkeepers and Fowler Middle School. These organizations provide tours and hands-on nature access to over 2000 children per year. A restored savanna will allow children to view the area’s native oaks, wild lilies and the creatures that this habitat supports.
What to Expect in an Oak Savanna Restoration
First, invasive and non-native plants, like English Hawthorn trees and turf and farm grasses, will be removed or eradicated. Removing these trees will create a more open area. Oak savanna restoration specialists will spray non-native grasses with a targeted herbicide a few times a year for the next several years. This work:
- Ensures native plants have time to become established without competition.
- Promotes wide, spacious growth habits and greater acorn production among the large, existing Oregon White Oak trees at the site.
In the fall, planting will begin in the savanna. The English Hawthorn trees will be replaced with native Black Hawthorn trees around the perimeter of the site. Native lilies, like Camas and Oregon Iris, will be planted. Dense sections of native grasses will be installed, making it harder for non-native plants to become established. Shrubs and Oregon White Oak trees will be planted in phases over the next three winters.
The site will be carefully monitored by a specialized re-forestation contractor through 2019.