Stories from the NFCCA Newsletter, the “Northwood News”

Northwood News ♦ April 2009

Warriors Wanted to Fight Ongoing Invasion

By Carole Barth

Inch by inch, our parks are being invaded.  Exotic invasive plants threaten to overwhelm the 24,912 acres of county parkland set aside for environmental protection.  Invasives also threaten all the undeveloped park acres (like Rachel Carson Meadow) as well as landscaped areas.  In fact, every year invasives swallow 14 million acres across the U.S.

An invasive plant is one that escapes cultivation and damages native ecosystems.  It’s not necessarily a plant that aggressively spreads in your garden.  For example, switch grass is a native plant that, in the garden, may crowd out slower growing plants. However, switch grass is a normal part of this region’s ecosystem.  It provides important winter habitat for birds and produces food for birds and mammals.  It’s part of the natural balance.

The pretty — but dangerous — Japanese Barberry in bloom.
On the other hand, consider the ubiquitous commercial landscape shrub, Japanese barberry.  This shrub may never spread in your yard, but its seeds are carried into the woods by birds and mammals where it alters soil pH, nitrogen levels, and biological activity in the soil.  Raising the soil pH (i.e., making it more basic) threatens the whole acid-soil loving plant community and the wildlife which depends upon those plants.  Barberry has also been shown to reduce the depth of the litter layer.  Leaf litter is where salamanders and wood frogs overwinter.  Many of our forests are already losing leaf litter due to the invasive European earth worm, so this is doubly bad for the amphibians.

So how do you know which plants are invasive? A guide to Mid-Atlantic invasive plants is available for download from the web at  You can also request a copy of the booklet by calling Jil Swearingen at the National Park Service (202.342.1443, ex. 218).  (This booklet also suggests native alternatives you can plant instead of invasives.)  You can also get handy fact sheets on individual invasive species at the Plant Conservation Alliance website at

Garlic Mustard has small white flowers and triangular-shaped notched leaves.
In 1962, Rachel Carson warned that the indiscriminate use of pesticides could lead to a “silent spring” where no birds sang.  Today, exotic invasives are the second-leading threat to biodiversity (after outright habitat destruction).  Bugs eat plants, and frogs and birds eat bugs.  In 2007, Douglas Tallamy’s book, Bringing Nature Home, documented that exotic plants cannot support enough native insects to preserve our birds and amphibians.  Thus, we truly are at risk of a silent spring.  This is especially poignant for our neighborhood, since Rachel Carson lived in the neighborhood across Northwest Branch and she and her nephew always made a point of listening to the frogs calling each spring around the Branch.

In 1999, Carole Bergmann, Montgomery Parks Forest Ecologist, created the innovative Weed Warriors program.  This was one of the first such volunteer programs in the region.  More than 500 citizen volunteers have been trained as certified weed warriors and have logged more than 23,000 hours to date controlling invasives in county parks.  Let’s keep the birds chirping and the frogs quacking.  Enlist as a Weed Warrior this spring.

What You Can Do to Help Save Our Parks

[Many of the URLs above have been changed/updated from those originally published in the newsletter.]   ■

   © 2009 NFCCA  [Source:]