Help Save Our City Forests
Hamilton Viewpoint: Duwamish Head Greenbelt, Seattle
Seventy percent of Seattle’s forests gone in twenty years? This is the projection of forest ecologists – if we do nothing about the spread of invasive plants. Himalayan blackberry, Japanese knotweed, Scot’s broom, English ivy, holly, laurel, butterfly bush, wild clematis, and yellow archangel are the worst of the worst, including some that nurseries are still selling.
After logging 150 years ago, the native forests of Douglas fir, Western Red Cedar, and Western Hemlock grew back with Bigleaf Maple and Red Alder. These short-lived trees face an even earlier demise with ivy strangling and weighting the canopy. When they’re gone, there will be little to hold the soil, and blackberry will smother any native seedlings attempting to germinate. The result is far more threatening than any midnight chainsaw, yet Seattle’s new tree ordinance does little to address invasives. It’s not a dramatic forest fire demanding immediate attention, but if we want to maintain the beauty, wildlife habitat, slope stability, property values, and the natural sponge that prevents millions of gallons of polluted road, lawn, and roof runoff from overflowing sewer systems and dumping directly into Puget Sound, then we must act.
Being an alarmist, I also worry about the loss of diverse habitat. Blackberry and ivy infestations are prime rat habitat (food and shelter). Rats eat bird eggs… fewer birds to eat insects… disease and insect outbreaks may be more likely (http://www.fao.org/docrep/009/a0789e/a0789e03.htm). Essentially, we’re losing our ecological checks and balances.
Rotting roots from an illegally cut tree result in slope soil movement
What can you do? Don’t dump or let landscapers infect your woods with yard waste. Don’t cut trees (unless hazardous) or take out stumps. Do safely remove invasive plants from your property, but wait if it will affect the stability of a slope. Do call a certified geotechnical engineer for immediate landslide concerns, and consider “vegetative management” (slowly replacing invasives with native plants) as a proactive approach to stabilizing forested slopes. King Conservation District (brandy.reed@kingcd.org) offers informative workshops on restoring nearshore habitat and stabilizing slopes. Also, KC’s Noxious Weed website (http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds.aspx) has good invasive species information. There are a number of companies that do native plant restoration in yards and forests, and I happily offer the names of my competitors — EarthCorps, Restoration Logistics, and Greenbelt Consulting — as the stakes are too high to misinterpret these warnings as self-interest.
Garden Cycles has a crew with some of the best plant ID skills in the field, and five are licensed herbicide applicators in in Aquatic, Right-of-Way, and Ornamental Weed categories (WSDA # 74158). We employ Integrated Pest Management and restoration best practices, but careful herbicide applications are the only practical way to get rid of some invasives – knotweed or holly will regrow with 20 times the stems if manually cut. We take efforts to minimize drift with cut and paint, frilling, or stem injection methods and use the safest products available for humans, pets, fish and wildlife. It must be said that glyphosate, the active ingredient in Roundup, has an acute toxicity four times safer than aspirin, is considered “practically non-toxic” by the EPA, is safer than many pollutants we tolerate daily, and far safer than neglecting the spread of invasive species.
