Make a Splash with Native Shoreline Perennials: Maintaining a balanced ecosystem with native plants

Arrow Arum provides lush, tropical foliage in the sun and shade.
Arrow Arum provides lush, tropical foliage in the sun and shade.

Plants are a key element of a balanced pond ecosystem. No matter how big or small the body of water may be, plants play an essential role in maintaining good water quality and a healthy, balanced habitat. Some of the functions plants perform include bank and soil stabilization, nutrient uptake from the water column and providing a habitat for everything from beneficial microbes, insects, fish and amphibians to ducks, small mammals and songbirds. Plants also provide us with visual aesthetics, with their showy flowers and blocks of texture and color throughout the seasons.

For inspiration, look to natural ponds and lake shores. Take note of natural meanders, curvilinear lines and subtle transitions. Observe interactions between plant groupings and their dispersal. With a keen eye, notice the influence of seasonal high and low water on the various plants and where they occur.

It is important to not “box a design in” and only focus on what will grow in the water. A fully encompassing design begins well above the water and takes into consideration every step of hydrological influence approaching the water’s edge and down three feet into the pond. Each zone plays an important role in the fabric of a healthy pond.

Zonation of aquatic plants

Dry Meadow/Upland
Perhaps the most overlooked and underappreciated zone around a pond is the high meadow. This is the “buffer zone,” the first area through which runoff must flow to reach the pond. For this zone to function as part of the whole, taller grasses and some trees and shrubs would be recommended. More often than not, this area is mowed turf grass, essentially rendering it non-existent. It is in this zone that runoff water will be slowed down and sediments and debris will be trapped before reaching the pond.

Wet Meadow/Saturated Soil
The wet meadow or high marsh zone around a pond functions as a buffer, much like the high meadow zone, but is hydrologically influenced during times of flooding or seasonally high water. The soils in the zone tend to be saturated for part of the year and support more traditional wetland vegetation and moisture-loving wildflowers.

Marginal Aquatic Vegetation/Low Marsh (0-6 inches)
Enter the zone where the water meets the land. This is a dynamic area, very sensitive to erosion from wave action, foot traffic and grazing. It is here that aquatic perennials such as sedges (Carex spp.), soft Rush (Juncus effusus), Swamp rose-mallow (Hibiscus moscheutos) and Blueflag iris (Iris versicolor) work to stabilize the bank and provide cover for amphibians and small fish.

Emergent Aquatic Vegetation/Shallow water (6-12 inches)
The shallow water zone is teeming with abundant aquatic life like spawning fish, toads and frogs as well as dragon- fly larvae and other macroinvertebrates. The plants that occupy this zone tend to be colonizers spreading with modi- fied roots called rhizomes. Examples of colonizing perennials include Pickerel rush (Pontederia cordata), Bullrushes (Schoenoplectus spp.), Lizard’s tail (Saururus cernuus) and Burreed (Sparganium spp.). A few clump-form- ing perennials that occupy this zone and spread only by seed include Arrow arum (Peltandra virginica), Golden club (Orontium aquaticum) and Water plan- tain (Alisma spp.). These plants help break up wave action before it reaches the marginal zone, provide excellent cover for wildlife and aid in nutrient uptake from the water column.

Floating Leaf Aquatics/Open Water (12-24 inches)
These are the true aquatic plants. The Water lily (Nymphaea odorata), American lotus (Nelumbo lutea) and Spadderdock (Nuphar lutea) all emerge from the bottom sediments with a petiole stretched to the surface leaves. These plants provide essential shade and cover for deeper water where algae and other potentially undesirable species would otherwise dominate.

Submergent Aquatic Vegetation/Open Water (24-36 inches)
Submergent aquatics (SA) form the foundation of a balanced aquatic ecosystem, playing a vital role in nutrient absorption, particulate filtration and oxygenation. They function as a biological particulate and chemical filter while providing critical cover and oxygen for countless invertebrates and the predators that consume them. Often referred to as “oxygenators,” most water gardeners consider them essential to a balanced ecosystem. Many native options are available that can provide interesting forms as well as function. These include Water-celery (Valisneria americana) and Floating leaf pondweed (Potamogeton nodosus).

Design Process/Site Analysis

The first step in formulating a good planting plan for a pond or lake is to define the objective and primary use of the water body. A pond that is to be used for swimming will have a completely different plan than a pond that is to be used for maintaining a fishery. A good planting plan takes into consideration the primary objective and balances it with the need for aquatic vegetation to achieve a functioning, healthy ecosystem.

Secondly, consider the entire water- shed of the pond. Special attention should be paid to the primary and secondary sources of water. It is in these areas that plants can be used to slow water down, trap sediments and aid in nutrient removal before reaching the main water body. Also note the prevailing windward and leeward sides of the pond. This will help identify areas of organic deposition, as well as areas that may need plantings to help keep wave action from reaching the shore. Wind can be used as a natural means of dispersal of seed as the plantings become mature.

Inventory existing vegetation; note non-natives and potential problem plants as well as desirable populations that can be enhanced. Note certain views and areas for access. Try to identify the seasonal high and low water line. This is especially important when planting the marginal zone, where a difference of four inches of water will determine survivability of certain species.

Implementation/Planting

When planting in an earth-bottom pond, plants native to that region should be used. Most all-aquatic plants are opportunistic in nature and can be aggressive in certain situations. That’s not to say every plant has that potential, but special consideration should be taken in the plant selection.

Always work backwards in the mud to minimize foot traffic in the soft sediments, smoothing out any footprints as you go. To minimize disturbance, open up the smallest hole possible to plant; unconsolidated mud cannot be compacted and should not be dug like normal garden soil. Most importantly, never step at the waterline — always step over it when entering and exiting the water. This practice will help maintain the integrity of the bank.

After planting, protection from predation in areas of high goose pres- sure is a must until the plants are established, which can take up to three years. Techniques to keep the geese out range from black plastic-coated wire fencing at the shoreline and in the water to mono- filament line strung across and around a pond to prevent landing. Once the plants are established and the exclosure comes down, special attention should be paid during nesting season and fall migration times. Geese can also be prevented from landing through either human or canine harassment. Following these few simple practices will help ensure the success of a shoreline planting. Remember to first lay out the primary objective and use of the water body before planting anything.

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