I thank Luke McGuff (who works in North Beach Park) for telling me about the Bradley Method of “bushland regeneration.” The method is named after two sisters, Eileen and Joan Bradley, who developed a successful method of restoring native vegetation to degraded natural areas in Australia. Their ideas are relevant anywhere, including our backyard forests in the Puget Lowlands.
The Bradley Method begins by locating core areas that have healthy populations of native plants without major infestations of invasives. Then, the non-native plants are removed in narrow bands around the core areas, minimizing disruption of the soil by only using hand weeding. The cleared bands are kept “weed free” until native plants have had enough time to spread into them at which point the next bands are cleared. Clearing of weeds always moves from less-infested areas towards more-infested areas, the pace of clearing is set by the pace of natural regeneration, and “over-clearing” is avoided.
I’ve been using much the same strategy with my narrow “weed breaks” around problematic invasives like Creeping Buttercup and Hedge Bindweed. I came to them out of necessity, having too little time to address all of the major problem areas, but wanting to at least contain the worst invasives while focusing my efforts on less degraded spots. The Bradley Method also seems relevant to the problematic edge areas where canopied forests meet adjacent open areas.
I have observed the negative consequences of over-clearing in my work in Forest Park. For example, in April of 2015, in less than three hours, two dozen strong volunteers from the U. S. Navy cleared a 5,000 square foot blanket of thick Ivy growing beneath a canopy of Western Redcedars and Norway Maples. The following October, another large volunteer work party installed a mix of 250 native plants, only 25% of which have survived (partly because of lack of irrigation). Since then, I have spent about a dozen hours each year clearing the area of re-emergent Ivy and annual invasives, but the area remains relatively barren except for scattered Sword Ferns and a few Redcedar saplings. If the Bradley Method had been used, there would probably still be a blanket of Ivy covering part of the area, but perhaps the rest would be better colonized by natives, and my annual maintenance would be a few hours instead of a dozen. Maybe we have to rethink our tolerance for Ivy blanketing the ground.