Riparian Buffer Resources

• Plant Native Perennial Plants – those native to the state and appropriate to your site conditions and therefore better adapted to survive and support local wildlife

Native plants are essential to sustain diverse wildlife populations, and the location (such as the compass direction—hot late afternoon sun, or predominantly north exposure) and soil (sandy or with a log of clay) will help dictate the best plants to use. Proximity to moving water also needs consideration because of saturated soils and potential for strong currents and flooding.

• Plant a Diversity of Plants

The greater the mix of plants—different species of trees, shrubs and perennial ground covers—will maximize buffer effectiveness. This also provides greater habitat for wildlife species and the capacity of multiple below-ground root structures to build soils that can remediate pollutants. A diversity of plant species will also help to minimize pest and disease problems and provide greater resistance to flood waters.

• Create Layers of Plants

To the extent that canopy trees, mid-story trees, shrubs, herbaceous perennial flowering plants (forbs) and ground cover can be maintained or added to your buffer, its capacity to remove pollutants, provide abundant habitat, and create effective screening will be enhanced. The deep roots of woody plants—trees and shrubs, in particular—are important to buffer effectiveness. Migratory and resident birds occupy and use particular zones of stratified woodlands, making these areas inviting habitat for them.

A diverse buffer doesn’t negate a view. In fact, a managed canopy promotes good air circulation, enhances understory growth, and can lessen damage from high winds. Periodic thinning may be necessary to maintain a desirable mix of woody species. A professional forester should be consulted.  

• All Ages Represented

Differing ages of plants (particularly woody species such as trees and shrubs) will ensure continuity over time as old vegetation dies (and becomes habitat and, eventually, soil) and young plants have the space to mature into gaps left by dead or downed trees. Younger plants are especially good at excess nutrient removal, and dead standing trees provide important nesting cavities and perching sites for birds and mammals.

• Leave Organic Matter on the Ground (and to the extent possible, standing dead wood)

The “litter” from your plants—leaves, twigs and downed branches and trunks, provides the carbon and nutrients necessary for a healthy soil—and that’s where much of the work of cleaning water happens. Those leaves and sticks also create the “roughness” at ground level that will slow and redirect polluted stormwater into the soil. Soil is your buffer’s work engine and it is fed by what the above ground greenery generates and eventually adds to the woodland floor. Leaf litter is also essential habitat for many of the insects that recycle organic matter, fuel the soil (and aquatic) realms, and feed many of the wildlife species that make riparian areas their home.

Other Important Buffer Considerations

If you are Stewarding an Existing Riparian Buffer

• Minimize soil disturbance that can result in the recruitment and spread of invasive, non-native plant species. Ensure any soil amendments are from a reputable source.
• Avoid soil compaction from traffic in the buffer in order to preserve infiltration capacity and ensure that soil microorganisms continue to thrive. Elevate walkways where possible.
• At the water’s edge provide (or don’t remove) downed or drifted woody debris that provides aquatic habitat structure.

If you are Amending an Existing Riparian Buffer

• Finer-textured and organic-rich soils typically have slower infiltration rates than sandy soils; consider amending your sandy soil to enhance the capacity to handle stormwater.
• Soils in inundation zones (where flooding takes place) need to be moderately permeable to encourage infiltration and will benefit from coarse, woody debris left on the ground to diffuse strong currents.

If you are Creating a Riparian Buffer                                                                                             

• Locate the buffer as close as possible to a known source of pollution; adjoining land uses need to be considered when designing the buffer width.
• Remove anything that impedes the flow of water into the buffer, such as a berm or raised garden bed. To control erosion on steep areas, use check dams (perpendicular to the slope) to slow water movement and increase retention time for the soil to work on pollutants.
• Wherever possible connect buffers where gaps exist along a waterway or waterbody
• When creating access to water through a riparian buffer, where possible design the access in a low-angle zigzag that is parallel to the slope to avoid creating an erosion issue.
• Create your buffer along the land’s contour to slow the flow of stormwater perpendicular to the slope, allowing it to infiltrate.

Other Buffer Types

Not all buffers are, or need to be forested, although higher rates of denitrification have been observed in forested buffers, and the woody stems and debris from trees and shrubs will offer greater flood resistance.  A buffer of grasses and forbs (a plant that doesn’t develop a woody stem, so it dies back to the ground in the fall) can still provide significant benefits for protecting water quality. Many grasses have extensive and deep root systems that make them effective at remediating stormwater pollutants and securing and enhancing the soil.

Grass buffers can also provide substantial habitat for wildlife, particularly when a diversity of plant species, including forbs, is used.  Native warm season grasses, such as Little bluestem (Schizachyrium scoparium), Indiangrass (Sorghastrum nutans), and Switchgrass (Panicum virgatum), grow in dense bunches with tall, rigid stems that provide year-round shelter and food for insects, birds and small mammals.

Inter-planting grasses with forbs will provide nectar, seeds and fruits for local wildlife, including pollinators, in addition to the appeal of flowering plants, especially if you diversify your plant selection to provide blooms throughout the growing season. There are many possibilities for plants to use with grasses, such as coneflowers (Echinacea spp.), bee balm (Monarda spp.), black-eyed Susan (Rudbeckia hirta) and asters (Symphyotrichum spp.).

The same principles for wooded buffers apply to non-wooded buffers: plant native, maximize plant diversity, create layers (heights and a variety of growth habits) and leave organic matter in place to build soil and secure habitat for insects and invertebrates.