Saving Regional Forests
Suburban Forests in Decline
Legacy logging transformed evergreen forests into remnants of deciduous canopy prone to ivy and blackberry infestations. Logging and development diminished the woody fungal-based topsoil that reduces flooding and filters stormwater. Roads further fragmented diverse plant and soil communities that help protect forests from disease, drought, and fire. Tree-topping and the loss of deep-rooted native plants increases the rate of natural landslides and unnatural weed invasions of shallow-rooted plants. When non-native species establish, they prevent the regrowth of native trees and understory, decimating species diversity necessary to sustain birds, wildlife & pollinators. Deciduous alder and maple forests are short-lived, potentially becoming "ivy deserts" and blackberry patches. "Restoration" requires removing invasive plants, replanting native trees and understory, and periodic weeding. Restoration of healthy forests supports "eco-services" like clean air, clean water, carbon sequestration, pollination, and wildlife food chains. Evergreen trees intercept twice the winter rain as deciduous trees, shading out weeds and filtering toxic stormwater. |
Invasive "seed rain"
English ivy goes to seed when it climbs vertically, creating a sail that topples trees. Ivy then spreads by bird into neighboring properties and forests. I00 years to after the first introduction in Seattle, English ivy completely covered over 50 percent of urban forests This is a snapshot of our region after another century of neglect given ivy's slow, relentless spread. This could create region-wide monocultures prone to Norway rat infestations, threatening ecological and human health. 
Count five English ivy seedlings in two square feet of forest floor, re-infested one year after removal of invasive plants
To reduce the epidemic nature of ivy's seed rain, the single most important step that anyone can do is cut ivy off trees. This saves the tree and prevents ivy from going to seed, thereby slowing its spread.
Removing entrenched ivy must be done carefully to avoid soil erosion and weed re-infestations. |
Invasive onslaught
"Old's Man's Beard" (Clematis vitalba) is another introduced vine that invades forests and topples trees. Clematis "seed rain" spreads by wind, tire treads, animal and foot traffic. Clematis is one of dozens of plants from other lands that are not evolved in our local conditions. Non-native plants often thrive in our mild northwest climate and outcompete native plants, reducing wildlife populations and throwing ecological checks out of balance. Other worrisome invasives include English holly, laurel, hawthorn, Scotch broom, Butterfly bush, knotweed, Yellow archangel, Poison hemlock, and nightshade, among others. English holly is doubling every six years, having “the potential to become a dominant species in both number and area covered within a few decades… and transform the region’s native forests on a large scale.” (Dr. David Stokes, UW). Many alien/exotic plants displace native plants that otherwise form a stable food chain necessary to feed insects and pollinators that feed birds, salmon, and humans. For more detailed information, see the public-service announcement: seedrain.org |
