Editor’s Note: This is part three of a three-blog series focused on OWC’s restoration process, from concept to completion. Our projects at Beaver Creek serve as a sort of ‘case study’ to illustrate these steps. We hope it will shed some light on the hard work that goes into our restoration sites, and inspire you to volunteer at a future event!
Restoration is a lot of work, but it can also be a lot of fun. After we’ve laid all the groundwork - both figuratively (planning and approvals) and literally (rough and loose) - it’s time for our favourite part of the restoration process: bioengineering.
“Soil bioengineering is the use of living plant materials to perform some engineering function. Soil bioengineering techniques can be used to treat eroding banks, excess gravel and unstable slopes and can provide a finished product that treats the problem as well as providing appropriate riparian vegetation.”
One simple and inexpensive bioengineering technique is willow staking: literally planting willow stakes into the soil, where they will grow roots and shoots, thereby stabilizing streambanks, restoring riparian vegetation, and providing habitat for terrestrial as well as aquatic species.
Willows are ideal to use for bioengineering because they:
propagate using vegetative reproduction, meaning that they can grow from cuttings,
grow abundantly in stands where they can be harvested sustainably,
like to “have their feet wet,” meaning they grow well in moist areas like streambanks,
grow relatively quickly, providing structural and ecological results in a relatively short timeframe,
are resilient and able to survive in dynamic ecosystems (e.g. flooding).
OWC and partners like Cows and Fish and Trout Unlimited Canada have found success in hosting volunteer willow staking events, as the work is labour-intensive, but the technique can be taught quite easily - and many hands make light work! Volunteers and partners at these restoration events have included ENGO staff, government employees, OHV recreationists, campers, college and university students, Scouts, families, and general community members. It is a lot of fun and oh-so-satisfying to spend a day outdoors, working together with community members to make a positive and visible difference to our environment.
Past volunteer restoration events
Prior to planting, the willows are harvested in the early spring or late fall, while they are dormant and have stored carbohydrates in their stems. Ideally they are kept cool and well-hydrated (e.g. partially submerged in a cold mountain creek) until they are planted in the ground.
To plant a willow stake, first we need a hole in the ground We use a custom-made planting bar, which is driven deeply into the soil using a sledgehammer - the deeper the better; 2-3 feet is ideal. The planting bar is pulled out and a willow is inserted, bottom-end-down. The soil is tamped down around the willow, and the top is cut off, leaving only about 4-6 inches sticking out above ground. This way, the willow won’t dry out, and is encouraged to produce plenty of roots below ground.
Willow staking at Beaver Creek, October 5, 2020. Counter-clockwise from top left: First, a deep hole is made using a sledgehammer and planting bar. A willow stake is inserted and gently tamped into the hole. The hole is filled and packed to ensure good soil contact with the willow. Finally, the top of the willow stake is trimmed so that only 4-5 inches remain above ground.
By planting most of the stake underground, most of the apical meristems (cells that will develop into roots or shoots) grow roots, providing the willow access to water and nutrients before it tries to invest energy in growing shoots and leaves. We liken this to wanting a firm foundation below-ground before building a house on top! These roots will also act like rebar, helping to stabilize the streambank and reduce erosion, and filter runoff before it reaches the stream. As the willow grows shoots, the leaves will shade the stream, keeping the water cool for aquatic species like native westslope cutthroat trout.
Willow staking is only one of a plethora of bioengineering techniques, each designed to address a particular site issue. Polster Environmental outlines a variety of bioengineering methods developed to treat everything from steep slopes (e.g. wattle fences, modified brush layers), excess moisture (e.g. pole drains), moving water (e.g. live silt fences, live gravel bar staking), slumping soil (e.g. live smiles, live reinforced earth walls), and lack of shade (e.g. living shade).
Various bioengineering methods have been developed to address different issues, from steep banks to poor drainage to lack of shade. Images used with permission from polsterenvironmental.com
Another way to control erosion is to bury bundles of live willow stakes, called fascines, perpendicular to the slope. These fascines installed at Beaver Creek in June had already grown shoots and leaves when we revisited in August!
To finish it all off, when appropriate we like to “top-dress” our restoration site with coarse woody debris - scattered logs, branches, leaves, etc. Coarse woody debris:
creates shelter for new vegetation
provides nutrients
captures sediment
At Beaver Creek, coarse woody debris added to our restoration site shelters the willows, captures sediment, and provides nutrients as it decomposes.
Nice weather and a delicious, locally-sourced lunch make for a great day! At Beaver Creek, we enjoyed smokies from Broek Pork Acres.
The Beaver Creek Restoration Project is a collaboration between OWC and Cows and Fish. It is funded in part by the Habitat Stewardship Program for Aquatic Species at Risk (Fisheries and Oceans Canada), and the Watershed Resiliency and Restoration Program (Alberta Environment and Parks). Thank you for your support!
