On the Trails: Arboretum Boardwalks

The boardwalk from B1–B2 in Curtis Prairie runs over a stormwater channel and through a patch of invasive reed canary grass.

The boardwalk from B1–B2 in Curtis Prairie runs over a stormwater channel and through a patch of invasive reed canary grass.

Arboretum trails invite hours of exploration for thousands of visitors. The nearly 20-mile trail system winds through prairies, savannas, woodlands, and wetlands, offering recreational opportunities for hikers and runners; scientific exploration for birders, botanists, and naturalists; inspiration for artists and photographers; and respite for anyone looking for a place to enjoy the outdoors.

The trails also play an important part in the Arboretum mission, which includes fostering the land ethic. They offer visitors a way into a natural environment where they can appreciate and connect with the land. Trails also provide land care staff, restoration work parties, and volunteers access to the lands they conserve and restore. Staying on paths minimizes land disturbance and ecological issues, such as trampling plants, spreading invasive species, and disrupting wildlife and habitat. The trails are much more than a way to get from point A to point B.

Trail conditions are heavily affected by weather. Downed trees, erosion, ice, mud, and standing water are recurring maintenance issues. Rangers, land care staff, and volunteer stewards work year-round to keep trails safe for visitors.

There are also long-term challenges—one of these is aging boardwalks. Boardwalks are often installed in or near wet low areas, such as springs, ponds, and wetlands that are home to diverse plant and animal populations. Wetlands are unique habitats and important ecosystems that can help slow the flow of stormwater, provide flood control, and filter pollutants to improve water quality. They are also ecologically sensitive and provide a poor foundation for structures, which are susceptible over time to rot, instability, and deterioration.

Skunk Cabbage Bridge was closed when the bridge support posts broke.

Many of the Arboretum’s boardwalks are at least 20 years old and show signs of decline and even failure. Most notably, Skunk Cabbage Bridge (SCB) and the trail from K5 to the bridge were closed in April when the bridge support posts broke (the viewing platform is still standing and accessible from the west at K4). Repairing the bridge and reopening the trail are now high priorities.

At the time SCB failed, planning was already underway to repair the boardwalk through central Curtis Prairie (A6–B2), which offers access to the interior of the tallgrass prairie. The goal is to reroute it slightly to bypass stormwater flow and rebuild it to be wider and sturdier.

The need for repairs on multiple boardwalks at once prompted Arboretum staff to assess all 3,955 linear feet (3/4 of a mile) of boardwalks.

Boardwalk repairs are costly: the SCB project is currently quoted at $10,000 and central Curtis Prairie repairs are estimated to be $15–20,000. They also require technical and ecological expertise. In evaluating the boardwalks, we considered use, specific purpose, current condition, and ecological considerations. Important factors include the value of access for visitors and staff; the ecological impact of the boardwalks and their use; changes in federal safety standards, including more stringent railing requirements; and resources needed for repairs as well as long-term maintenance.

As we evaluated each boardwalk, we considered various outcomes. While much project planning is still in process, we began to prioritize boardwalk repairs by urgency, and also discussed which ones could simply be monitored for the near future. We also looked at decommissioning some boardwalks, and have decided to remove two in the coming months.

The first is N7–N8 in a wetland area of Wingra Woods. Under current environmental regulations, it’s ecologically inadvisable to repair. The boardwalk does not provide unique access, as visitors can see Big Spring and its wetlands from the K4–M1 trail section on higher ground. The value of protecting this wetland area far outweighs the costs and disturbance of repair, so we will remove the boardwalk and decommission the trail segment.

B1–B2 through Curtis Prairie (which links to A6–B2 mentioned above) is increasingly affected by stormwater flow so heavy that it sometimes shifts the boardwalk during large storm events. Erosion around the support posts creates a drop-off that could require a railing to meet new safety standards. The boardwalk also passes through a patch of reed canary grass, which could be inadvertently spread by visitor traffic. A short nearby segment (B5–B4–B3) also provides access to the firelanes. Due to redundancy, invasive species management, and stormwater, the boardwalk and trail segment from B1–B2 will also be removed.

As changes occur on the landscape, new ecological considerations develop and the original use and purpose of the trails and boardwalks evolve. Decommissioning these boardwalks will improve conservation and restoration efforts in these wetland areas. Repairs on other segments are still pending, and we will continue to monitor and evaluate the trail and boardwalk conditions.

—Christy Lowney, Arboretum ranger