This was originally posted to: Guemes Island Planning Advisory Committee

GIPAC Annual Meeting: Noah Booker Presentation on Native Plants for Shoreline Restoration

GIPAC Annual Meeting: Presentation on Use of Native Plants in Shoreline Restoration, by Noah Booker of Shelterbelt, Inc.

Noah Booker, a Native Plant Specialist and Arborist with Shelterbelt, Inc., gave an informative, practical, and very useful presentation at the annual GIPAC meeting on November 19, 2016.  Noah discussed “Coastal Bluff Restoration and Revegetation and Restoration 101” and provided valuable information on how to successfully utilize native plants in shoreline protection and restoration projects.

GIPAC plans to build on Noah’s informative presentation as it develops the concept of organizing a “plant bank” on Guemes Island.  A plant bank would include nursery sites on the island for cultivating native plants that could provide plant material as needed for revegetation projects over time as needed.  GIPAC will post more information on this project as it is further developed.

Following is an outline of Noah’s presentation.

 Shelterbelt, Inc.

Revegetation and Restoration

Licensed, Bonded and Insured:  SHELT**972JS

www.shelterbeltinc.com

 

Noah D. Booker, Native Plant Specialist and ISA Certified Arborist WE-4312A

2406 Broadway, Bellingham, Washington 98225-2402

Telephone: 360 920-1902 

noah@shelterbeltinc.com                                                                      November 2016

 

Coastal Bluff Revegetation and Restoration 101:

Coastal bluffs and shorelines have an outsized ecological role to play in providing for a healthy marine environment.  They are the narrow “ecotone” or mixing area/buffer between land and sea.  Shoreline property owners have a responsibility to be good stewards of these sensitive and dynamic areas.  The good news is that our own self-interest as landowners dovetails neatly with a healthy shoreline:  a dense, diverse community of native plants which knit the steep slope together while providing many other benefits, including seasonal flowers, fragrance, fruit and fall color; increased abundance of songbirds, pollinators and other wildlife and a regionally distinctive, natural look that enhances this unique place in the world.

 

Site Evaluation and Planning: 

History of site, history of slumps/problems; disturbance/fill, riprap/hardened shorelines.  Consult with a geologist who specializes in coastal bluffs.

Water:  It is essential to manage water on coastal bluffs, especially concentrated runoff from roofs/gutters/hardscapes.  Tightline water in sturdy pipes to base of slope, do not disperse water onto slope.  Slope soil saturation = slumps.

Soils:  texture, organic content, colluvium, seeps; poor soils on coastal bluffs are often the reality. 

Slope aspect:  North/South/West/East; Slope %/steepness.

Existing vegetation, native vs. weeds, trees vs. shrubs, shading vs. sunny.  Consider habitat value for songbirds and pollinators, aesthetics and future view issues as well.

What vegetation type are you aiming for?  Depends greatly on site conditions.  Look around at nearby properties, what is your reference slope?

Go with native plants.  Generally best to aim for dense, diverse plantings of native trees, shrubs and ground cover, providing multiple canopy layers for natural beauty and long term slope stabilization.

 

Site Preparation:

Weed control vs. weed management.  Weeds generally have inferior erosion control characteristics and are typically the #1 challenge to any revegetation project.  Site preparation is critical!  Varies greatly by site.  Many weeds need to be controlled before any other work happens.  Common weed challenges on Salish Sea coastal bluffs include Himalayan blackberry, reed canarygrass, English ivy, Scotch broom, laurel-leafed daphne, poison hemlock, morning glory/bindweed, English holly, etc.  Each weed has specific control strategies, techniques and timing.  Use an Integrated Pest Management (IPM) approach.

Slumps and slides, steepness, need for jute fabric/erosion control blankets, turf reinforcement mats/engineered geotextiles.  Generally I don’t use ECBs or jute unless the site is very steep, with loose, sloughy soils, or has a recent slump.  I prefer biodegradable materials.  Crib boards or small logs (eg peeler logs) placed horizontally on slope can be helpful for planting pockets and for access. 

Mulching:  Mulch type is important.  Use clean, weed-free mulch.  Bark is not good.  Wood chips do not hold well on a slope.  Use hog fuel, also known as stump grindings, tub grindings, hogged mulch, biomulch.  Has woody material and fibers; if placed properly and packed down with a pitchfork as you go it holds really well on a steep slope.  Place it thickly, i.e. 6” deep.

Remember to plan for maintenance access to slope i.e. “goat paths.”  Foot traffic can be very damaging; use ladders, ropes and an abundance of caution.

 

Installation: 

Timing:  Best to plant in fall/winter to allow natives to get good root establishment before the summer dry period.

Plant densely.  If a denuded slope, go with 3-4’ centers.  Use a regular, triangular planting pattern; this helps greatly with knowing where plants are during maintenance.  Flag plants with brightly colored plastic flagging so they don’t get lost.  Blue tubes or white spiralwrap vole tubes can be appropriate for some sites depending on weeds, deer, rabbits, wind, etc.  Generally I don’t use tubes or plant protection on coastal bluff jobs unless the site demands it.

Bareroot vs. container stock:  For larger projects, bareroot is cheaper.  Some plants do really well from bareroot, including snowberry, Nookta rose, ninebark, twinberry, willows, etc.  Bareroot plants can be “slip planted” into the soil with minimal disturbance, are cheap and easily moved around, and you can carry 100 or more in a planting bag.  Some are not available (sword fern, salal) or grow more slowly/less dependably (tall Oregon grape).  Bareroot plants take longer to get established and grow more slowly at first, plant densely. Typically minimum of 50 plants per single species bundle.  Bareroot plants available from Fourth Corner Nursery, WACD and from Conservation District plant sale; must pre-order, cost usually <$2 or so each.

For smaller projects 1 gallon sized plant material is often the best choice.  1gal pots have a good root mass but are still small enough to handle and install on a slope.  Better root mass = faster establishment, lower mortality.  Plant on 3-5’ centers, triangular pattern.  1gallon stock available from Plantas Nativa Nursery, typically $6-10/each.

Cuttings/live stakes:  Some plants do really well installed as live stakes into moist sites, especially willows.  If you cut your own make sure you positively ID your plants, there are a lot of the invasive, non-native crack willow along Whatcom County shorelines, especially Bellingham Bay, as well as other non-native willow plantings.

 

Favorite plants for coastal bluffs:  Check your reference site, what is growing nearby on similar slopes.  Generally aim for native plants that are tough, adaptable, with dense, aggressive root systems, especially rhizomatous (spreading) types.

Trees:  *Douglas fir, Western red cedar, grand fir, *shore pine, *Douglas maple, Sitka and *Hooker willows.

Shrubs for sunny/drier sites:  *snowberry, *Nootka rose, red flowering currant, oceanspray, tall Oregon grape, serviceberry, Lewis’ mock orange.

Shrubs for shadier/moister sites:  salmonberry, *twinberry, *thimbleberry, *ninebark, red osier dogwood, Indian plum.

Favorite plants for top of bank:  salal, *snowberry, *thimbleberry, slough sedge, sword fern.  Easily maintained for height, no thorns.

Ground covers:  *salal, *Western sword fern, strawberries:  *wood, sand, Virginia.  Sandy top of slope:  Pacific dune grass.

* = My favorite revegetation plants for coastal bluffs.

There are many other appropriate native species to use, these are just plants with which I have had a lot of success on the coastal bluffs.

 

Views:  Maintain as much existing tree cover as possible to protect slope and balance privacy and bluff health.  Favor trees like Douglas fir, cedar and madrona over alders and cottonwoods.  Do not top trees.  Frame your views and use appropriate pruning methods like windowing, limbing up/”raising the skirt”, etc.

 

Maintenance and Monitoring:

This is where revegetation projects most commonly fail; maintenance is critical to success.  Weeds are the biggest threat and the biggest challenge.  Balance weed control/management with potential for disturbance to slope.  If weeds grow up and shade out your natives, the planted stock will just disappear and die off quickly.  Control methods include hand weeding, weed whacking/string trimming, herbicides, etc.  Use great care if considering herbicide use; careful, spot applications that are carefully timed; follow all regulations, read the label.  Generally best to avoid any herbicide use on slopes except when necessary due to weed types eg morning glory/bindweed, knotweed, Canada thistle, etc.

Deer, European cottontail rabbits, voles:  Can devastate new plantings, though typically not on the steepest slopes.  I have had luck with PlantskyddTM non-toxic deer repellent, applied 3-4X/year.  Temporary fencing can be excellent.  Generally not as much of an issue on coastal bluffs, unlike in wetland/riparian plantings.

Watering:  As little as possible, to keep that weight off the slope.  After the first two summers the plants will rarely need any supplemental watering. 

Evaluate how things are going and be ready to make adjustments.

 

Things to Avoid:

Placing fill, building close to top of bank.  Directing gutters or concentrated runoff near the bluff.  Topping trees.  Any major disturbance near top of bank.  Broadcast herbicide use.  “Clearing” vegetation on the bluff or top of bank.  Uninformed slope work.  Planting non-native, invasive plants such as ivy, holly, laurels, cotoneaster, pampas grass, butterfly bush, etc.

 

General Thoughts:

Coastal bluff stewards have a real responsibility to take care of their slopes; your actions or lack thereof have an outsize effect on our natural systems.  Plants are a key part of a stable slope but plants alone cannot solve serious slope instability issues.  Every site is different, the site should guide what you do.  Remember that it took a long time for your slope to get degraded, so take a short, medium and long term approach to your project (It’s okay and even advisable to take on larger projects a piece at a time).  <