Protecting clean water and restoring fish and wildlife habitat are at the core of Metro’s parks and nature mission.
Nearly half of the money from the levies is dedicated to protecting water quality and habitat. Restoration and maintenance work includes controlling invasive weeds, planting native trees and shrubs, removing unnecessary or harmful culverts and roads, maintaining existing roads and infrastructure, decommissioning unauthorized trails, improving connections between streams and wetlands, and improving habitat for fish and wildlife.
After Metro acquires a property, a stabilization plan is drawn up as the first step of the management process. Invasive weeds start getting treated. Sometimes, dilapidated buildings, septic systems and other manmade structures are removed. This initial work is paid for with money from the 2006 natural areas bond measure.
After a site is stable, a site conservation plan is developed to identify the most important actions to improve water quality and fish and wildlife habitat at the site. A site stewardship plan is also developed that details weed treatments and maintenance of fence lines, signage and more. Restoration work can take years or even decades to complete, after which a site transitions to long-term maintenance.
Restoration takes different forms across the forests, rivers, wetlands, prairies, oak savannas and other habitats that make the region a beautiful and fascinating place to explore. It means treating invasive weeds choking out rare native wildflowers. It means thinning overcrowded forests and planting native shrubs. It means removing asphalt and concrete from riverbanks and planting native plants in their place, or strategically creating log jams and placing giant root wads into streams to create habitat for endangered fish. In every case, restoration and maintenance make for better habitat, cleaner water and a more enjoyable visit.
Invasive ludwigia threatens to choke aquatic habitats, devastate ecosystems
At first glance, the delicate yellow flowers appear rather pretty. But glance up, and you realize the plant’s leaves and branches stretch all the way to the horizon. In just two weeks, this green monstrosity has doubled in size, growing into a thick, dense mat on the shoreline along Bybee Lake and into the water.
This is invasive ludwigia, an aquatic plant native to South America that is threatening to choke backwaters, oxbow lakes and warmer river channels in Oregon. Ludwigia could destroy these special habitats and harm water quality, damaging native plants, amphibians, fish, birds and other wildlife. But it’s not too late to avoid the worst, and various groups are battling ludwigia, including Metro at Smith and Bybee Wetlands Natural Area in North Portland.
“As I say to people in lectures, this one is the game changer,” said Glenn Miller, an invasive plants specialist at the Oregon Department of Agriculture. “It is so impactful that you’ll see open bodies of water that just convert to anaerobic mudholes in probably 20 years and really exclude most other life. No other aquatic plant we have had in the state does that.”
Experts suspect ludwigia arrived in Oregon through aquariums, which often get dumped into local waterways when people no longer want them.
Ludwigia has the potential to devastate aquatic ecosystems by outcompeting native grasses, forbs, sedges and other plants that form the basis of healthy habitats. When invasive ludwigia covers an area, migrating shorebirds can’t stick their beaks in mudflats to eat bugs, and wintering ducks and waterfowl find less rice cutgrass and other native seeds and plants.
Ludwigia can also lead to poor water quality, said Elaine Stewart, a senior natural resources scientist at Metro. Ludwigia depletes the water of oxygen, which native fish and invertebrates in the wetlands need.
“Ludwigia can throw an entire ecosystem out of balance,” Stewart said. “Complexity is good in an ecosystem, and ludwigia simplifies it.”
Metro staff first spotted invasive ludwigia at Smith and Bybee Wetlands in the mid-2000s. Large-scale treatments started in 2014, thanks to money from the parks and natural areas levy approved by voters the previous year. In 2014 and 2015, intense treatments from July through September helped keep ludwigia under control. In 2016, crews faced their biggest challenge, tackling a 60-acre monoculture that had developed on Bybee Lake.
Each year, contractors start by hand pulling and spraying a glyphosate-based herbicide on ludwigia growing around the lake. The first round of treatments usually occurs in late June using canoes to reach floating mats away from the water’s edge. The herbicide prevents floating mats of ludwigia from taking root on the lake bed as the water level drops.
As new plants grow on the exposed lake bed, crews strap on 4½ gallon backpack sprayers and walk around to treat the ludwigia. At the height of the growth, crews use a 700-foot hose connected to an ATV to reach patches far from solid ground.
“I’m hopeful we’ve turned the corner and are pushing ludwigia down,” Stewart said. “Invasive species are forever. It takes a lot of resources.”