Growing Greener: The Sustainable Sites Initiative

The following was published as part of my regular “Growing Greener” column in Public Garden magazine, Vol. 23 No. 3/4 (2008). Public Garden is the flagship publication of the American Public Gardens Association. In “Growing Greener” I answer sustainability-related questions from public garden staff.

Q: What is the Sustainable Sites Initiative, and how can public gardens use it?

A: In the past several years, the LEEDR program of the U.S. Green Building Council has become synonymous with sustainable design. The USGBC awards four levels of LEED certification for the design, construction, and operation of high-performance green buildings: Certified, Silver, Gold, and Platinum. This rating system has provided targets for public gardens and other institutions striving to go green.

One limitation of LEED, especially for public gardens, is that it currently is concerned primarily with buildings. It’s not surprising, then, that two public gardens, the Lady Bird Johnson Wildflower Center and the United States Botanic Garden, have teamed up with the American Society of Landscape Architects to produce the Sustainable Sites Initiative, the first program to develop guidelines and standards for sustainable landscapes.

“The Sustainable Sites Initiative will clearly communicate the social, economic, and environmental benefits of sustainable landscape practices,” says Heather Venhaus, the Wildflower Center’s SSI program manager. It will not only provide specific sustainability benchmarks and targets for public gardens but also, in Venhaus’s words, serve “as an educational tool for visitors illustrating the positive impact they can have in their own landscapes.”

The Wildflower Center, USBG, and ASLA have partnered with a variety of stakeholder groups and a voluntary group of professionals who provide technical expertise on five subcommittees that cover the SSI’s major areas of focus: Hydrology, Soil, Vegetation, Materials (which includes maintenance issues like green waste and the use of chemicals), and Human Well-Being. The U.S. Green Building Council, one of the stakeholder groups, anticipates that once the SSI standards and guidelines have been developed, they will be incorporated into LEED.

The SSI will consist of three “products.” A draft Standards and Guidelines report consisting of best practices for sustainable landscapes, divided into the five major categories listed above, is now available on the SSI website.

The next step is producing a Rating System, as in LEED, in which sustainable landscape benchmarks are assigned weighted credits, and an award or other recognition system with various levels of sustainability achieved is defined. This will be followed by a phase in which the Standards and Guidelines and the Rating System are tested in a number of pilot projects. The knowledge gained in these real-life examples will be incorporated in a Reference Guide to demonstrate how the credit system works and to aid creative problem solving.

One of the most innovative features of the SSI is that its standards and guidelines are based on the “ecosystem services” that landscapes provide — natural processes such as crop pollination by bees, birds, and other animals. Flood protection, air and water filtration, and greenhouse gas regulation by the soil and vegetation are among the other natural landscape functions that the SSI aims to protect or restore. These processes are essential for both healthy ecosystems and healthy human communities.

Sounds good, but what will this really mean in practice? In the future, the SSI is likely to guide public garden collections and landscape displays in a number of intriguing ways.

The collections of most public gardens have long reflected traditional garden aesthetics and plant systematics. This has resulted in features such as formal herb gardens and herbaceous flower borders, as well as collections that focus on taxonomic groups, like cycads or orchids. Taxonomic collections often serve a scientific purpose, and traditional design elements are an important part of our cultural heritage, so these are highly unlikely to disappear, although the SSI will no doubt result in ornamental plantings that are more regionally appropriate — less reliant on irrigation and fertilizer, for example. Ray Mims, the U.S. Botanic Garden’s SSI representative, likens these traditional landscapes to the Old Masters at art museums. An art museum upgrading to a more energy-efficient HVAC system wouldn’t get rid of its Old Masters, he says, but rather “adapt the system to the appropriate humidity and temperature.”

However, the SSI’s focus on achieving ecological goals is likely to lead to new types of plantings and collections based on natural models in the regional landscape. One important ecological goal, for example, is protecting or restoring the area’s natural hydrological cycle. In a natural landscape, plants, along with the soil, absorb rainfall, so there is generally little runoff. By contrast, in our built environment we have radically altered the natural hydrologic cycle, destroying wetlands and replacing natural vegetative cover with roofs, paved paths, parking lots, and other impermeable surfaces. As a result, huge volumes of storm-water runoff flow in to storm sewers, carrying pesticides, motor oil, and other pollutants to nearby streams and rivers, fouling surface waters and destroying aquatic life through sheer physical force.

What kinds of landscape designs and plantings aimed at restoring natural hydrologic function can we expect as SSI increasingly exerts an influence on public gardens? Rain gardens, green roofs, and green walls, modeled after local plant communities that survive in similar conditions, are among the features likely to become prominent elements of the 21st century public garden. At the moment, many of these sustainable design features are still being created by engineers, restoration ecologists, and others concerned more with functionality than beauty. Public gardens have the opportunity to transform ecological functionality into a new art form, creating spectacular green roofs, wetland gardens, and other sustainable plantings that wow their visitors and inspire them to grow these new ecological gardens in their own homes and communities.

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