Why Riparian Planting Is A Good Approach For Creating Habitat

A Reminder of Why We Are Planting

The 2019 ” Bow Valley Riparian Recovery and Enhancement Program is now in the works. More riparian planting will add to the existing five years of planting that has already been completed. To date, over 60,000 native willows and trees have been planted on over 30 kilometers of stream bank. The riparian planting program encompasses three area streams that are tributaries to the Bow River: Bighill Creek, West Nose Creek and Nose Creek.

The long term goal of the program is to restore native willow and tree riparian growth along sections of these creeks. The native plants will also help regrowth of native plants by introducing seeds from these indigenous willows and trees into areas downstream of the planting area. Both fish and wildlife will benefit from the newly created habitat, both in the water and along the streams banks. The existing trout population in Bighill Creek, West Nose Creek and the lower reach of Nose Creek will increase as a result of the improvement of available habitat.

The water quality and quantity will improve on all three streams, as the new riparian zone develops along the stream channel. A healthy riparian zone creates a natural filtration buffer that helps to reduce the amount of surface nitrates and other organic compounds that enter the stream. The native willows and trees will also reduce the amount of silt loading into the stream channel. Tonnes of soil, clay and silt presently being washed into the stream channel at a number of erosion sites along all three streams in the program. By planting on the loose eroding slopes, the root systems will eventually provide stability to the sluffing soil and clay, allowing new growth to retain any loose soil.

Once stream banks are stable with new growth the stream channel bed will eventually clean itself of many tonnes of silt that has accumulated over the years, exposing cobble, boulders and gravels on the streambed. The constriction of flow created by new willow growth along the water’s edge will increase velocity in the stream channel and help scour down thru the silty bottom. The newly cleaned bottom gravel, cobble and boulders will result in a more healthy aquatic ecosystem.

Newly exposed gravels and rock on the streambed will enhance the invertebrate habitat and increase the food supply for resident stream trout. More exposed gravel will increase spawning habitat for trout and other important course fish, like minnows and suckers. An increase in food for trout will result in an increase in the trout numbers, which will benefit both wildlife that depend on trout and other fish for food, and sport anglers that recreate on the small streams.

The Willows Above: were planted four years earlier on Bighill Creek. They are now providing good shade and cover habitat for both trout and nesting song birds.

The willows Shown Above were planted in 2015, now they are established enough to provide stream bank stability. This photo was taken in July of 2018, three years after planting. Willows were also planted on the opposing stream bank, in native water sedge and canary grass, but those willows are slow growing and they will take a number of years of growth, before they stand out on the landscape. Annual seed production on the native willows and trees will also help recruit new riparian plant growth. Out of the millions of seeds cast along the creek, only a few will germinate and take root, if the growing conditions are favourable.
Eventually, beavers will move into the section of stream that has enough native willows and trees to maintain a lodge and family. This is just part of the natural process. If the beaver activity is properly managed, in an urban or suburban setting, the stream will benefit. Bow Valley Habitat Development plans on planting on the outer perimeter of any beaver dams that are constructed. The permanently wetted perimeter is an ideal location for new willow and tree growth. The beavers do not bother with newly planted small willows and trees. By the time the willows are large enough to feed beavers, they can survive any grazing and continue to grow. This is one of the many reasons that BVHD uses small diameter cuttings for growing native stock. The collected, small diameter cuttings, are grown until they have both root and top development, before they are ready for planting.
It is very rewarding to witness the slow recovery of a native riparian habitat, bringing it back to the streams historic appearance and knowing that the stream’s bio-diversity will also return over time.

Brown Trout Spawning

Brown trout spawn in the main-stem of Bighill Creek and West Nose Creek, some of our local area streams. Due primarily to the larger size of adult brown trout, they require a larger stream for reproduction. The brown trout will select suitable spawning habitat, where there is adequate gradient, depth and velocity of flow. On streams like West Nose Creek, in Calgary, there is limited available spawning habitat further upstream on the creek. It is important that those habitats that are presently utilized by brown trout receive extra attention and protection. Bow Valley Habitat Development is working closely with Calgary Parks to insure that these concerns are prioritized and in the future, we can develop a management plan to enhance trout reproduction on the West Nose Creek.

Presently, there is a stream bank riparian restoration program underway on West Nose Creek and Bighill Creek. The “Bow Valley Riparian Recovery and Enhancement Program” has resulted in the planting of native willows and trees along the water’s edge of both of these streams. The new willow and tree growth will enhance both trout habitat and their spawning habitat, over time. The riparian willows and trees will help to constrict the flow in the stream channel, cleaning the silt out from the bottom and exposing existing gravels, cobble and boulders in the future. It has been proven that woody debris in a stream channel will enhance spawning habitat by causing the collection of suitable sized spawning gravel at areas where submerged wood collects small to medium sized gravel.

Another good collection site for spawning gravel, is directly below beaver dams that have been breached by high flows. The plunge of large volumes of water over a beaver dam creates a scour hole pool just below the dam. The hydraulic jump loosens and frees existing gravel in the streambed and trout will utilize this newly freed gravel for spawning beds in future years. The beavers need native willows and trees to survive, so our riparian planting program will help to create a suitable living habitat for beavers, in future years. Bottom line is; trout streams tend to take care of themselves if there is adequate flow of water and a healthy riparian zone to enhance the streams flow and create habitat for both wildlife and fish.

About Guy Woods

I am Director of Bow Valley Habitat Development, based in the Town of Cochrane, Alberta, Canada. I love to fly fish and it is this past time that prompted me to get involved in the field of riparian and fish habitat enhancement. I have been working in this pursuit for over 40 years!
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