Sustainable Landscapes —

(continued from page 39)

• What are current uses of the surrounding area? Are there active factories nearby? Busy roads? A strip mall? An airport?

Improving Air Quality

From the street canyons of Chicago to suburban backyards, air quality issues also provide an opportunity for choosing native plants. “I was really glad to see all the honeylocust planted as street trees in Chicago,” commented Fuselier. “There was a study done of common street tree species where honeylocust was shown to have above average removal of fine particulates from the air. With that many trees present in the urban landscape; it has a real positive impact on air quality. Plus, they were spaced out enough so that you don’t have a solid canopy. Green ceilings, as they’re called, just hold airborne pollutants such as ozone close to the ground where pedestrians are. This is especially important in cities like Chicago where buildings restrict lateral air flow. You’ve got to have good spacing between the street trees to create ventilation to allow the ground level air contaminants a chance to rise.”

Plants can not only assimilate airborne pollutants in their tissues, but also help trap them, reducing particulate levels in the air around us. Needle-leaved species like pine, spruce, juniper, and arborvitae can help clean the air. “The needle-leaved species have higher tissue surface area,” reported Fuselier. “The small spaces between the needles are also able to trap airborne pollutant particles and help reduce the amount of particulate matter in the atmosphere. It’s not a case of quantities of particulates getting absorbed into the plant. Most of them will land on the surface of the leaf and eventually accumulate. Then they either fall down to the ground or get resuspended into the air, but at least it reduces the amount of particulate matter in the air pretty immediately.” Waxy and fuzzy leaves also do an excellent job of capturing airborne particulates, so consider planting species like bayberry, inkberry, and holly where appropriate.

Managing Stormwater and Runoff

Perhaps the most easily recognizable use for natives is to assuage erosion along edges of waterways and to assist in controlling stormwater runoff. Many native grasses with their deep, fibrous root systems do an excellent job of holding soil in place at the edges of ponds, streams, lakes, and drainage systems. What you may not know is how these plants can also break down contaminants via phytostimulation. Phytostimulation is the ability of the plant to pull apart organic contaminants in the soil via enhanced microbial activity in the plant root zone or rhizosphere.

“If I’m working with our engineers on a detention pond project, I’m looking at what drains into that pond,” commented Fuselier.

(continued on page 42)