A healthy riparian buffer consists of a diversity of native plants that help protect the waterway as well as its inhabitants.
A riparian buffer is an area of land that borders a stream, pond, lake, river, etc. A healthy riparian buffer consists of a wide section of vegetation, preferably forest, that buffers a waterway from the surrounding land and vice versa.
WHY DO THEY MATTER?
Riparian zones provide critical services for aquatic ecosystems, terrestrial ecosystems, and people as well. These services include:
- Streambank stabilization – The roots of large trees help keep the streambank soil locked in place, and prevent it from eroding into the waterway.
- Pollution and excess nutrient filtering – Trees and other plants naturally extract pollutants and excess nutrients from our soil, both of which have the potential to severely degrade water quality for humans and wildlife alike. A lot of money is spent on cleaning our waterways, but plants provide a variation of this service free of charge.
- Flood prevention – Riparian forests absorb a lot of rainwater. This slows down the release of storm runoff into the waterway, which in turn reduces flood intensity. Trees and shrubs within riparian buffers also physically slow down floodwaters, which reduces damage downstream.
- Temperature stabilization – Large trees hanging over waterways provide shade both to the understory and the stream, which stabilizes temperatures within them. This creates optimal conditions for a wide variety of wildlife (and fishermen too).
- Source of nutrients for the stream – Leaves and even branches from overhanging trees eventually fall into the water, which provides a vital source of nutrients for the aquatic food web. And while it’s true that riparian buffers work to absorb excess nutrients, they also return some of it, slowly, at optimal concentrations. Leaves and branches also provide structure to the stream that functions as a habitat for invertebrates, fish, amphibians, and other wildlife.
- Carbon sequestration – Trees and other plants are masters at extracting and storing carbon dioxide, which is a major contributor to climate change.
- Provide habitat for wildlife – A wealth of wildlife species rely on healthy riparian buffers. They provide habitat for birds, mammals, insects, reptiles, and amphibians. Furthermore, the protective effects of riparian buffers create optimal conditions for aquatic organisms as well.
Conversely, having little to no vegetation (mowed lawns, for instance) along waterways offers little in the way of streambank stabilization, pollution filtering, flood prevention, temperature stabilization, nutrient cycling, carbon sequestration, or habitat for wildlife.
HOW YOU CAN HELP: NATIVE PLANTS FOR YOUR STREAMBANK
The best way to help a struggling riparian buffer ecosystem is to plant native trees. It’s best to plant flood-tolerant tree species that grow to be relatively large. Large trees can be further supplemented with smaller native trees and shrubs, to increase the structural diversity of the buffer. Increasing structural diversity both improves the strength of the buffer and creates a variety of spaces for wildlife to use.
Every property is a little different, so the success of planting certain species may vary. It’s best to consider what species already exist in your area and the overall site conditions, as plants have different tolerances of flood intensity, soil conditions, etc. In any case, there are plenty of native species to pick from. Here are 5 native Pennsylvania tree species that might be great additions to your riparian buffer:
Black Willow (Salix nigra) – is a large, flood-tolerant native tree species known to host many butterflies and other insects. This willow looks a lot like the non-native weeping willow, but provides a much greater ecological benefit because it has adaptive relationships with other PA species.
Swamp White Oak (Quercus bicolor) – is a large native tree species that provides food in the form of acorns for a variety of wildlife. These are long-lived and can contribute to your riparian buffer for multiple generations.
River Birch (Betula nigra) – is a fast-growing, flood-tolerant native tree species whose catkins provide food for a variety of bird species. Their roots are especially strong and are great at stabilizing streambanks. These trees are easy to recognize by their shaggy, peeling, yellow-white bark.
Silver Maple (Acer saccharinum) – is a large, fast-growing native maple commonly found along waterways. Their seeds are consumed by a variety of birds and mammals, and they serve as nest trees for herons, owls, and waterfowl.
American Sycamore (Platanus occidentalis) – are among the largest trees in the United States. They’re commonly found along waterways, and provide excellent habitat for a variety of birds including wood ducks, herons, and bald eagles. Their sprawling canopy helps provide shade to the stream and their roots stabilize the soil.
Lastly, for good measure, here are 3 native Pennsylvania shrub species that might make great additions to the understory of your riparian buffer:
American Elderberry (Sambucus canadensis) – is a native shrub that is great at helping absorb runoff and floodwater. Their dark purple berries provide food for birds and mammals. Additionally, their hollow stems provide great habitat for cavity nesting bees.
Buttonbush (Cephalanthus occidentalis) – is a flood-adapted shrub/small tree, whose red-brown seeds provide food for a variety of waterfowl. Their spikey white flowers also provide nectar to pollinators such as honeybees.
Silky Dogwood (Cornus amomum) – is a native shrub found bordering wetlands, streams, and ponds. Their clusters of white flowers are great for pollinators and their bright blue fruit are attractive to a variety of bird species.
For a more comprehensive list of native riparian buffer species, as well as where you might acquire them, visit some of the links provided below. I’ve also provided a link that shows where native plants are sold near you:
Thank you for reading, and happy planting!
Sebastian Harris, Conservation Easement Steward