PROFESSIONAL LANDSCAPE DESIGN The Art and Science of Wetlands

Cattails sway in the wind. Butterflies flit about. A frog croaks; a songbird coos. Welcome to the “nursery of life.” Welcome to a wetland. These unique ecosystems, whether they are marshes, swamps, bogs or fens, provide habitats for thousands of plants and animals. They also hold and slow floodwaters, reducing danger and damage, and absorb and filter nutrients, sediment and other pollutants before they contaminate bodies of water. Wetlands’ aesthetic and recreational advantages are the most apparent to the public – they provide a paradise for birdwatchers, hikers, photographers and nature-lovers of all kinds.

While the planning, design, management and construction of wetlands is far from a new process, as Jon Bryan Burley, associate professor of landscape architecture at Michigan State University’s School of Planning, Design and Construction, points out, scientific involvement in the process has increased in recent years. In addition, federal, state and local regulations have evolved over the last three decades, due in part to the Clean Water Act (see Wetland Regulations on page 12). Unfortunately, even with the awareness created by President George H.W. Bush’s 1989 declaration to sustain “no net loss” of wetlands, the United States still loses about 60,000 acres of wetlands per year due to pollution, hydrologic alterations from land development and vegetation damage including the introduction of nonnative plants, according to the Environmental Protection Agency.
 
The EPA estimates that 75 percent of all wetlands are privately owned. As public perception of the importance of conservation and sustainable landscapes rises, aided by federal funding for restoration and approval of compensatory mitigation projects, wetland-related projects will continue to present themselves to landscape architects and designers.
 
When designing landscapes adjacent to wetlands or restoring wetlands themselves, Burley emphasizes that no “cookbook” solutions exist. “It’s not like doing a math problem with a discrete answer,” Burley says. “There are a variety of variables and approaches that need to be carefully examined and considered,” he says. The first step in working with wetlands is to engage the proper experts. Depending on scope, a wetland-related project could require the involvement of landscape architects, wetland scientists, environmental planners and other ecological experts.
 
A buffer zone, or an adjacent area of upland, is one essential element that affects design – and it’s often required and regulated by state or local agencies. Essentially, a buffer functions as an extension of the wetland – filtering sediment, removing nutrients and providing and protecting wildlife habitats.
Buffers, which can range from 50 feet to several hundred meters (depending on local and state regulations), are also important in preventing the erosion of upland areas – one particular concern of anti-development activists, says Laurie Broccolo, president of Broccolo Tree and Lawn Care, a Rochester, N.Y.-based firm that provides environmental planning services to site developers, engineering firms and land owners. Creating a buffer, which also protects the wetland from human activities that could affect wildlife, is one vital part of developing a design that minimizes any disturbance to the existing site.
 
To transition from a mowed turf area to a wetland, Broccolo recommends the following order:

 • High-maintenance turf;
 • Low-maintenance turf and/or un-mowed meadow grass;
 • An almost-no-maintenance area of wildflowers and
 un-mowed meadow grass; and
 • The wetland.

Plant selection in the buffer zone and wetland itself is a vital element of design, as the introduction of non-native species can threaten sustainable wetlands. “It’s all about modeling after what occurs naturally,” says Curtis La Pierre, a senior landscape architect and planner with Seattle-based architecture firm Otak.
 
While it’s important to know what to plant in any particular region, knowing what not to plant may be a greater concern. “There are many wetland plants that are banned in many areas of the country,” Burley says. “Be familiar with what is not allowed in your region.” The U.S. Department of Agriculture’s Natural Resources Conservation Service offers an online tool for selecting native plants for wetlands at  http://plants.usda.gov/wetland.html. The Wetland Indicator Status allows users to search by region, growth habit and duration.
 
Also remember to match vegetation with the appropriate water regime (high, low or normal water levels) and fetch (the distance of open water to the shoreline), Burley says.
 
Designing with diversity in mind is a good approach, La Pierre notes. “We use a lot of different plant species – it’s taking the shot-gun approach,” he says. “If some don’t make it, others might. It’s a survivability approach.” Another tip from La Pierre: “We use small plants rather than traditional-sized landscape plants,” he says. “They have a lower mortality rate.”
 
In addition to a broad plant palette, attracting various species of animals and insects will add to the aesthetic value and longevity of a wetland. “We usually try to include some wildlife features in our wetland plans,” La Pierre says. These additions may include brush piles for rodents and small mammals, rock piles for amphibians and reptiles or a “snag,” a large log that’s planted upright. “You include those so you can get insects moving in and eventually have cavity-nesting birds occupy the logs. It’s all to help draw other wildlife.”
 
Finally, wetland monitoring is often the most important part of the process. When La Pierre’s firm prepares wetland plans it also includes a long-term maintenance proposal. While the goal for most wetlands is to become self-sustaining, the maintenance period after a wetland restoration project is typically five years.
 
“A big part of maintenance is weed control,” La Pierre adds, noting mechanical measures are preferable to chemical applications, due to wetlands’ close proximity in the watershed to streams and other bodies of water.  As a preventive measure, he recommends installing a 3-inch layer of wood-chip mulch, which keeps the ground moist and suppresses the weeds. “It gives the wetland plants a chance to get growing,” he says.
 
Buffer zone maintenance is essential, too. Areas of wildflowers and un-mowed meadow grass should be mowed down every three years, Broccolo says. This practice should take place in three sections on a rotating schedule – not all at once, to ensure preservation of the wildlife habitat.
 
Experience and application, too, play a role in long-term success. “Knowing everything in a book about wetlands may still not generate a good plan or design,” Burley notes. “It’s the combination of scientific knowledge with the art of planning and design that generates sound solutions.”