Wildlife in the Winter Garden

American holly (Ilex opaca).

Did you know Smithsonian Gardens joined Audubon International’s Cooperative Sanctuary Program? The goal is for the gardens and greenhouses at the Smithsonian to be designated as a Certified Audubon Cooperative Sanctuary. To become certified, Smithsonian Gardens has developed, implemented, and documented the results of an environment management plan in five key areas: site assessment and environmental planning, wildlife and habitat management, water, resource management, and outreach and education. We believe that Smithsonian Gardens has met (or in some cases exceeded) Audubon International’s environmental management standards in all five areas. We are looking forward to a site visit from an Audubon International staff member to verify Smithsonian Gardens submission.

Below is a list of plants that you can find in the Smithsonian Gardens that are native to the mid-Atlantic region and provide food and shelter to wildlife during the winter months.

• Ilex glabra, also called inkberry, is an evergreen shrub with black fruit called drupes. The fruit, attractive to birds, appears September through March. You can find this shrub in the Urban Bird Habitat Garden at the National Museum of Natural History.
• Ilex opaca, known as American holly, can be found on the south side of the Smithsonian Castle in the Enid A. Haupt Garden. This large evergreen tree provides nesting opportunities for birds and small mammals as well as bright red berries to sustain our feathered friends during the cold winter months.
• Ilex verticillata is a deciduous holly often called winterberry. Birds really seem to enjoy these beautiful berries so don’t forget that winterberries are dioecious, meaning that the berry-producing female plants need a male winterberry nearby to produce fruit. Look for Ilex verticillata on the north side of the National Air and Space Museum due east of the entrance.
• Lindera benzoin is called spicebush because of the spicy smell of the leaves when crushed.  We grow this tree for its year-round wildlife value. This tree is a host plant for the Spicebush Swallowtail butterfly and the fruit is eaten by songbirds. You can find this understory shrub in the landscape of the National Museum of the American Indian as well as in the Butterfly Habitat Garden at the Natural History Museum.
• Rhus typhina ‘Dissecta’ or staghorn sumac as it is commonly called is not only a picturesque plant but a source of reddish brown seeds that are consumed by many birds and small mammals throughout the winter months. The staghorn sumac is also a host and nectar plant for both moths and butterflies which is why you can find it in our Butterfly Habitat Garden.

Staghorn sumac (Rhus typhina ‘Dissecta’)

For more information on native plants for wildlife habitat: http://www.nps.gov/plants/pubs/chesapeake/pdf/chesapeakenatives.pdf

For more information about the Audubon International’s Cooperative Sanctuary Program:
https://www.auduboninternational.org/acsp 

–Shelley Gaskins, Smithsonian Gardens Horticulturist, Green Team Member 

Exploring DC Water

Smithsonian Gardens’ Green Team had a unique opportunity to visit the Blue Plains Advanced Wastewater Treatment Plant (AWTP) owned and operated by Washington, D.C.’s Water and Sewer Authority or DC Water.  Serving the District and nearby suburbs, the plant takes in more than 330 million gallons of raw sewage daily.

We had the pleasure of meeting with General Manager George Hawkins before getting a tour of the facility.  After just a few minutes spent with Mr. Hawkins you could immediately appreciate not only his vast knowledge but his passion for what he does.  He touched upon several aspects of DC Water, from its many large construction projects to its water treatment process  to sustainability.

General Manager George Hawkins details various aspects of DC Water.

The Washington Aqueduct provides the public water supply system serving Washington, D.C., and parts of nearby suburbs and is run by the U.S. Army Corps of Engineers.  DC Water takes wastewater and runs it through cleaning processes using mechanical, chemical and biological methods like screening, aeration, polymer use and bacterial digestion.  Once cleaned to EPA standards, this treated water is then put back into the Potomac River and the cycle begins once again.

One way DC Water is becoming more sustainable is with a huge construction project to further the biosolids management program with a Thermal Hydrolysis Process (THP) and digestion facility.  Once completed, the project will not only be the largest of its kind in the world, but also save DC Water around $10 million a year in energy costs and cut its usage by a third.  (DC Water is currently the largest consumer of electricity in the District.)  It will also reduce the amount of carbon emissions by approximately 50,000 metric tons yearly.  DC Water hopes to have the process up and running by July 2014.

George Hawkins actively looks for ways for DC Water to be more sustainable instead of simply taking the tried and true (easier) way out. Currently, any excess water generated during a large rain event that the facility can’t handle overflows into the city’s rivers.  DC Water’s Clean Rivers Project is a colossal undertaking that will help alleviate that issue; a huge cistern-like cavity is currently being built to gradually treat storm-water that overwhelms the system.  George also sees other ways of dealing with excess water, such as a push for individuals and the government on all levels to build bioswales, green roofs and rain gardens to help mitigate the problem.

The Smithsonian Gardens Green Team tours the Blue Plains Advanced Wastewater Treatment Plant.

One way the public can help be more water smart is by drinking more tap water instead of using bottled water.  To this end, DC Water is directly involved with a project called TapIt that is also found in other cities.  TapIt enables you to locate eateries (via internet search, iPhone app, or restaurants labeled with a TapIt sticker) that will let you bring your own water bottle and fill it for free.

DC Water hopes someday to become net zero for energy consumption meaning it would produce energy equal to or more than its daily needs.  With future plans to double the Thermal Hydrolysis Process and digestion facility and talks of installing solar panels, DC Water thinks it can achieve this lofty goal.  If everyone uses water more consciously and tries to alleviate polluting through trash and water runoff we can make D.C.’s rivers a major highlight of the city.

-Matt Fleming, Smithsonian Gardens Horticulturist 

Urban Trees – More Than Just Beautiful

Street and garden trees along Constitution Avenue at the National Museum of Natural History create a cool, green tunnel for pedestrians.

When people walk through the landscapes of Smithsonian Gardens, they often take pleasure in the beauty and majesty of the trees that are found throughout.  The large spreading canopies, colorful spring and summer blooms, and brilliant autumn colors make for a feast for the eyes.  Although we take great pride in the appearance of the trees here at Smithsonian Gardens, we also manage them for the numerous benefits that they provide, many of which are often not recognized.

Urban trees provide myriad contributions to the areas where they grow.  Some of those benefits include:

• Storm water runoff and flooding reduction.  It has been found that trees absorb the first 30% of most precipitation events through their leaf systems, and up to another 30% can be absorbed and held by their root systems.
• Traffic calming.  Research shows that tree lined streets have fewer and less severe traffic accidents than those with no trees.
• Reduction of air pollution.  Tree crowns capture and trap air pollutants, including automobile exhaust gasses and particulate matter.  The severity of asthma and other negative health impacts are reduced in the presence of trees.
• Carbon sequestration.  Trees absorb and retain carbon, thereby contributing to the reduction of greenhouse gasses.  A US Forest Service study found that the average annual carbon sequestration of urban areas in the U.S. is approximately 26 million tons totaling a $2 billion value.
• Lowering of air temperatures.  Urban areas can become extremely hot, as all of the concrete, asphalt and other hardscapes absorb heat throughout the day.  In areas with trees, air temperatures can be reduced by 3-10°F, and properly shaded neighborhoods can realize energy cost savings of up to 35%.
• Improve your health.  The findings of one study show that areas that have many trees can lower blood pressure, have a calming effect on teens and adults with ADHD, and contribute to overall emotional and psychological health.
• Add to property values.  Realtor based estimates of street tree versus non-street tree comparable streets show a $15,000-$20,000 increase in home or business value.

Trees in front of the Smithsonian Castle soften the hard lines of its architecture while helping to cool the building during the hot summer months.

So, the next time you’re enjoying the trees here at Smithsonian Gardens, remember all of the wonderful and helpful things they’re doing for us!

–Greg Huse, Smithsonian Gardens Arborist and Tree Collection Manager

Sustainable Lawns at Smithsonian Gardens

Smithsonian Gardens continues to make significant improvements to its lawn maintenance program, which in turn has contributed greatly to institution-wide sustainability efforts. Since 2008 Smithsonian Gardens has reduced its fertilizer runoff and pollution to the Chesapeake Bay Watershed, reduced pesticide applications, and reduced the total number of mowings each year. This year we are experimenting with more environmentally-friendly lawn maintenance equipment and collaborating with University of Maryland Cooperative Extension to evaluate the use of different types of grasses that require less maintenance.

Smithsonian Gardens is asking its contractors to switch to more eco-friendly mowing equipment.

In 2010, we started reducing lawn mower emissions by asking our mowing contractor to switch their riding mower from gasoline to propane. Our mowing contractor has switched all of its mowers over 42 inches from gasoline to propane powered. In addition, the contractor has agreed to replace all of the gas-powered handheld equipment it uses (backpack blowers, stick edgers, and string trimmers) with battery-powered equipment. The contractor hopes to replace its 21-inch gas-powered mowers with battery-powered mowers this summer thereby eliminating all gas-powered lawn equipment used by the contractor.

Evaluation of various types of grass at the Smithsonian Gardens Greenhouse Facility.

Smithsonian Gardens and Maryland Cooperative Extension have teamed up to evaluate different types of grasses that require less maintenance. Fine fescue grasses have a reputation for being environmentally friendly as they require less water, fertilizer and–most important–less mowing. Last fall, we planted 10 x 10 foot plots of creeping red, chewings, sheep, and hard fescue grasses at our Greenhouse Facility in Suitland, Maryland. All the grasses were planted in the existing soil as well as in compost-amended soil to determine the best way to establish them as a lawn. The goal of this project is to determine which types of fine fescue grasses will work best in our climate. If they require less maintenance and can still be considered an acceptable lawn, we hope to use these types of grasses in the future.

Both of these initiatives have made Smithsonian Gardens’ lawn care program substantially more sustainable and do much to contribute to a healthier Smithsonian community and environment.

-Graham Davis, Horticulturist