Plants have roots.They have roots that intertwine, roots that mat together, roots that penetrate deeply and anchor around rocks, roots that prevent soil from washing away. Nature has done a pretty good job holding things together since the last ice age 10,000 years ago. Attached to these roots are a variety of remarkable plants, shrubs and trees that have evolved over 10, 000 years with each other and with mammals, insects and avian species to create some pretty extraordinary ecosystems.
More and more landscapers are turning to native plants and methods that mimic natural processes to restore degraded sites along shorelines and in upland areas. If you live on waterfront, you’ll want access to the water to reach a dock or a beach. The ideal is to minimize the amount of native vegetation that you remove to create a path. For level sites a soft path is kindest on the land. For steeper sites, steps or a snaking path may be necessary. A path will act as a water course during heavy rains so top your path with wood mulch to help slow and absorb water. If your slope is very steep and you’re using rock, make it local granite which is available nearby and aesthetically fits in with the surrounding land. Don’t ignore the value of plants when you are putting in hardscapes like steps, patios and retaining walls and wherever practical choose plants over hardscape to solve problems and create esthetic spaces. Place plants close to hard scape features to hold the soil in place and plant them densely.
Bearberry would be a good choice for planting around steps and paths since they are widely available, hardy, low growing, sun loving and thrive in poor sandy soil.
Photo credit Sten Porse CC-BY 3.0plants
Shorelines cloaked in vegetation fare better than properties cleared of shrubs and trees and planted in grass. Steep banks do well planted in Willow shrubs, Speckled Alder, Beaked Hazelnut (Corylus cornuta) and Red Osier Dogwood, named for its red stems. It is the tenacious plant roots of these shrubs that hold the soil in place. These plants have adapted to extreme conditions and will survive periods of flooding and then long periods of little rain. They are deciduous and can be pruned aggressively to maintain views. There are many other plants that can tolerate a range of conditions that make them ideally suited to shorelines and the vagaries of the weather. For other plant choices please peruse the article on Solutions to Erosion .
Hard surfaces like steps and retaining walls do nothing to slow the flow of water from the top of a slope or prevent the force of a river or wave action from slowly undermining these structures. Engineers have found that rip rap is not always effective in stabilizing the shore but merely armours it for a period of time. Rip rap does a poor job of absorbing the energy of water and merely deflects waves to the edges undermining neighbouring properties. Placing plants in rip rap to accumulate organic debris from roots can help.
Restorationists are now opting to use vegetation and softer organic materials. In serious cases a steep slope may need to be cut back to reduce the angle and then clothed in coco mat to hold the disturbed soil in place until plant roots spread enough to take over this function. Coconut fiber rolls and mats placed along a shoreline can absorb and redirect water and can be planted so that plant roots can eventually take over.
Ideally we want to take care of water before it reaches the shore. And to do that we need to assess the state of the landscape from the shoreline back to your property line. We would need to consider how many buildings and parking areas with impervious surfaces, grass vis a vis a many layered woodland are in place. A landscape of different layers allow light to penetrate to all plants – low perennials, understory, upper canopy.
Erosion has a lot to do with upland management. The ideal is to have the ground water from rainfall and runoff be absorbed, filtered and cleaned before it runs down the slope to the water body. Bio swales, raingardens, and undulations in the landscape can all be used to hold water and give it time to absorb into the ground.
Forests filter and regulate the flow of water. Leaves capture and slow the fall of rain to the forest floor. The ground acts like an enormous sponge, absorbing up to 46 centimetres (15 in) of precipitation before gradually releasing it to streams and recharging ground water. On average an untouched forest floor can absorb 2/3rds more rain than a cover of suburban turf.
Well vegetated upland areas can still offer a view. Deciduous shrubs and trees can be thinned, and branches removed with little effect on the vegetation. It’s called ‘vista pruning’ and looks more attractive than a clear-cut swath down to your lake. Use brush and other available organic matter to build soil to reclaim poor soil areas. It may take a few years for twigs and branches to break down in our temperate zone with our short summers and cool evenings, but you’ll eventually be rewarded with rich, moist soil ideal for planting natives. If you can’t wait, you can make a hole in the brush, add soil and plant. Brush piles also act as habitat for wildlife so you may want to have a succession of soil building projects on the go.
Build swales or ditches and then plant them so that plant roots can take up excess water. A bio swale allows surface water to soak into the earth slowly, rather than flooding or shooting down to the lake. Use rocks, logs and any other natural debris to slow down the flow of water and arrest erosion. Place logs perpendicular to a compacted and steep path to direct water to the sides. Use wood chip mulch on the sloped pathways as it is absorbent and is a soil builder. As tempting as it may be, please avoid planting fast growing invasive ground covers like periwinkle (Vinca) and Goutweed (Aegopodium podagraria).
Plants, with their varied root systems blanket and protect the soil from drying out and from blowing or eroding away. They also aerate the soil and provide nutrients to the soil from decaying foliage. Organic material has the additional benefit of providing texture and nutrients to your soil as it breaks down.
An effective and affordable solution for any terrain but particularly steep slopes is the use of wattles which are simply bundles of organic material, possibly coco rolls. Live stakes and/or steel rods are used to hold the material in place. The live stakes are cuttings taken from shrubs such as willow and dogwood, that quickly set down roots. The use of live stakes can only be used in early spring and the stakes can be bought or cut from existing vegetation before leaf out. Buttonbush, elderberry, viburnum, willow and dogwood are all sold as live stakes. Buy dormant and plant in April/May.
How to obtain plants:
The nursery trade has a very small inventory of native plants, so you’ll have to be creative.
Celebrate what you have, prune, move and enhance.
Transplant or divide from plants on your property.
Collect seed from friends.
Purchase sustainably grown plants
For a list of local landscapers, arborists and nurseries please visit our Buy Local page
Carolyn Langdon, Master Gardeners, 2023