"Our shorelines need to remain as intact as possible, with a mix of trees and shrubs," she says. "But we may not need a dense, native forest. There likely are designs that are compatible with both lakeshore development and sustaining lake food webs."
Greenroofs can save cities millions of gallons of water
Having a garden on your roof isn't just nice for a garden party; it can make your city more environmentally friendly. Many American cities are beginning to incorporate greenroofs into their planning ordinances because they recognize that, planting a rooftop garden can offset heat, increase city biodiversity and decrease stormwater runoff. This runoff can be problematic in cities where rainwater is funneled by streets and parking lots directly into streams, carrying with it chemicals and debris and increasing the risk of flash floods.
But the plants on greenroofs can absorb some of this water "like a sponge being saturated," says Olyssa Starry, a graduate student at the University of Maryland at Baltimore County. Starry studied a greenroof atop a Baltimore building in comparison to a similar building without a greenroof to determine how well the roof would absorb water from frequent storms. By measuring water flowing out of building downspouts, she found that the greenroof retained from 30 to 75 percent of water from storms, compared to a negligible amount retained by the building with no greenroof.
Although her results are preliminary, Starry thinks that cities can reap benefits from making greenroofs a part of their building requirements, as cities like Toronto and Berlin have recently done. Using GIS satellite imagery, she estimated the number and area of buildings that could hold greenroofs within one watershed in the Baltimore area. If all these roofs were greened, she says, the city could save the watershed
|Contact: Christine Buckley|
Ecological Society of America