When most of us think about Greenbelt Land Trust, the first place we often think of is Bald Hill Farm. In fact, Bald Hill Farm is only one of many areas managed and protected by Greenbelt. In its 30 years as a nonprofit, Greenbelt has protected over 3,000 acres in four counties (Benton, Linn, Polk, and Marion). These protected areas contain a wide range of ecosystems from prairies and oak savannas to aquatic habitats such as rivers, wetlands, and streams. While some of these areas, like Bald Hill Farm, are open to the public, others are owned by private landowners and are only accessible through Greenbelt-led tours. Two such areas are the Horseshoe Lake and Little Willamette conservation areas. These areas are special in that they contain ecologically unique habitats: oxbow lakes and floodplains.
Horseshoe Lake is an oxbow lake, which is a U-shaped water feature adjacent to the main channel of a river. These features are ecologically important because they provide a still water, or lentic, habitat for aquatic organisms such as fish and invertebrates. Oxbow lakes form as the river naturally bends or meanders. Once a meander forms, sediments are deposited and eroded and the meander eventually gets cut off from the main channel. These processes are able to occur in sections of the river that have not been artificially straightened, or channelized, by humans. A river needs the physical space of a floodplain to meander in. Currently, Greenbelt is working to restore the floodplain habitat at Horseshoe Lake.
The Little Willamette site is another area protected by Greenbelt and the landowner. This site is unique because it contains important floodplain habitat. Floodplains also provide slower-moving lentic habitat for aquatic organisms and act as fish nurseries. Young fish will often inhabit the quiet waters until they are ready for the hustle and bustle of the main channel. When the waters at Little Willamette rise and eventually begin to inundate the floodplain, juvenile Chinook salmon can take advantage of the abundant food and habitat resources. The large surface area and plentiful food resources of an inundated floodplain make them highly productive ecosystems. Biological productivity is a function of the total mass of organisms in a given area, or biomass, in a system. This biomass translates into energy in the form of food for organisms that live both in and out of the water. There are many fish and birds that call floodplain habitats home for these reasons. To date, Greenbelt has worked to restore approximately 60 acres of floodplain habitat at Little Willamette.
I recently joined Greenbelt on a Wildflower Walk & Picnic at Little Willamette and explored its fascinating habitat that helps increase biological diversity and productivity of the Willamette River and the adjacent riparian zone. Next time you are out enjoying the Mulkey Creek Trail in the Bald Hill area, take a moment to stop by the creek. Notice the small meanders in the creek- these are the same processes that form an oxbow lake on a much smaller scale. The protection and preservation of these aquatic systems are a part of the important conservation work done by Greenbelt Land Trust. Join Greenbelt for special tours at Horseshoe Lake, Little Willamette, and other conservation areas to see it for yourself!
Blog post and photos by Erica Johnson, Greenbelt Volunteer Naturalist