Lake Barcroft  


Reflections on the RPA Garden

 Reflections on the RPA Garden

By Betsy Washington - Dec 2007

The new Resource Protection Garden (RPA) by Beach 5 has exceeded our wildest expectations despite the record breaking drought this past year, and the recent vandalism and destruction of plants. This demonstration garden was designed to protect and restore the riparian buffer zone at Beach 5 following the guidelines for Resource Protection Areas along Fairfax County watersheds. An equally important goal was to demonstrate the beauty and adaptability that native plants offer our neighborhood gardens.  

Why are riparian buffer zones so important? The streams that feed Lake Barcroft, drain over 15 sq miles including most of Falls Church, stretching as far as Vienna and Tyson’s Corner. Much of the forested shorelines that once occurred along the streams have been lost to development.  Unfortunately this only serves to increase the velocity and amount of storm water that rushes down the streams into Lake Barcroft as we witnessed in the June deluge two years ago. Riparian buffer zones along the lake and streams act like giant filters and sponges by slowing and absorbing the flow of storm water and by filtering out the sediments, pollutants, and oils carried downstream from roads, parking lots, and developments.  

The Demonstration Garden is a Showcase for Native Plants & Wildlife: In addition to functioning as a riparian buffer zone along the shoreline, the garden features a broad array of plants native to the Chesapeake Bay watershed that bloom from spring through late fall. Many also offer showy fruit, beautiful bark, and brilliant fall color. If you visited the garden this fall, you will have noticed dozens of butterflies and moths flocking to the clouds of fall blooming plants like the goldenrods, asters, coneflowers, Joe-Pye weed and blue mist flowers.  Ruby throated hummingbirds hovered over the brilliant red blooms of cardinal flowers planted at the lake's edge, as well as the tubular flowers of turtleheads and coral honeysuckle. Goldfinches fed on the seeds of the coneflowers and black-eyed susans, while chickadees were busy feeding on seeds and berries as well as insects attracted to the plants. Downy woodpeckers searched for insects in the peeling bark of the river birches. The rose mallow and swamp hibiscus were still flaunting a few flashy blooms right up until the last frost.  And the beautiful fall blooming witchhazel waited until late October to begin opening its spidery yellow flowers with their elusive

The Possumhaw viburnum flaunted showy clusters of pink and blue fruit, and the winterberries and red chokecherries are still covered with glossy red fruit that will last through much of the winter, and feed flocks of winter hungry birds.

Why Native Plants? Several people have asked why native plants are so important and why we just don’t let the vigorous alien plants take over the shoreline since they grow so well?  The most important reason is that alien plants are not a functioning part of our ecosystem.  Our native insects and wildlife have co-evolved over thousands of years with our native plants and have developed specialized adaptations that allow them to safely feed on them. Few if any of our native insects and butterflies are able to feed on ornamental alien plants from other areas of the world. 

Native Plants Support Wildlife: Native plants featured in the RPA garden support hundreds of species of butterflies and other insects. Our mighty oaks support more wildlife than any other native plant group, with recent research finding over 500 species of butterflies and other insects that depend on oaks as well as dozens of species of birds and mammals. Oaks are followed closely by other trees such as the wild cherries and river birches (> 400 spp.), hickories (>200), black gums and dogwoods (> 100 spp.). Goldenrods and asters lead the list of perennials that attract butterflies and pollinators (>100 spp. each).  Gardens planted with native plants support more than 35 times as many butterflies and birds than those planted with the ubiquitous alien plants such as burning bushes, Bradford pears, evergreen azaleas and of course, lawns. Not only that, they support many uncommon nesting birds that raise their families nearby. 

The Link Between Native Plants, Insects, and Songbirds: Without a diverse population of insects and butterflies, our songbirds and other wildlife could not survive. At least 96% of our song birds raise their young only insects and caterpillars. Loss of native plants and the insects that depend on them has greatly reduced the survival of baby birds. People have commented about not seeing as many chickadees and other songbirds around the lake in the last few years. This is not surprising since songbird populations have declined by nearly 50% since 1966. Suburban neighborhoods have removed most of the plants that insects and other wildlife depend on for survival. Add this to the average of 100 acres of forest/ day that has been lost to development in the Chesapeake watershed since 1985, and you have a recipe for disaster.

So how can we make a difference in our own neighborhood and gardens?  First and foremost protect and preserve your native trees.  They support more wildlife than all other plants combined.  Second, try adding a few native plants to your garden or replace plants that have died with native species. Perhaps a native vine like the American Wisteria or Coral Honeysuckle would look fabulous growing up a fence or trellis. Consider reducing your lawn by adding a few small native trees like serviceberries, dogwoods, or witchhazels underneath your tall trees.  But don’t stop there. Tuck in a few native shrubs such as wild azaleas, viburnums, or winterberry. Then tie it all together with native groundcovers and wildflowers.  Let the plants in the RPA demonstration garden serve as your inspiration, and while you are there, be sure to check out the fascinating insects, butterflies, and birds that are making this new garden their home.  Compare this to the typical suburban patch of lawn and ask yourself, how many insects or birds do you see?