Create a Vegetated Buffer

A vegetated buffer is a strip of grass, shrubs, and trees running parallel to the water body. They are made from plants that are separate from your lawn. The EPA recommends that these strips should be used in all coastal water protection activities [1]. Vegetated buffers are comprised of layers whenever possible to ensure it achieves the desired effect.

On Fishers Island, we are concerned about nitrogen from fertilizer runoff and septic leakage, so our buffers need to contain plants that can slow the flow of surface and ground waters. Tall, densely planted native grasses are the most effective plant type to slow surface water runoff. The first, most landward side of your buffer should contain a strip of native grasses. This will ensure that the water slows enough to allow the nitrogen to be absorbed into the plants before running into Long Island Sound. Lawns are not a suitable substitute for this layer, as they are often cut too short to significantly affect flow.

Native hardwood trees and shrubs should form the second layer of your buffer and be closest to the water. These plants have deeper roots that can reach the deeper flowing water that contains nitrogen from septic tanks and cesspools. Nitrogen can be tricky to filter out of the water, so this layer of trees and shrubs will also absorb nitrogen that has sunk into the soils from the first grassy layer of the buffer [2].

Vegetated Buffers Work for You! [3]

  • Buffers help prevent erosion.

    44% (excluding Alaska) of the US coastline is experiencing significant erosion. The roots of the vegetated buffer bind the soil and prevents the soil from washing away due to waves, tides, and storms.

  • They improve wildlife.

    Buffers that are just 15 m wide can provide vital habitat for birds such as osprey. Smaller buffers can still be used as feeding grounds. As buffers widen they can provide even more wildlife services such as supporting songbird communities, providing small mammal habitat, and creating a breeding site for birds.

  • Buffers are nice to look at.

    An increase in visual diversity corresponds to an increase in visual appeal. By diversifying your vegetated landscape, you can increase the visual value of your property. Plan your buffer so that you can increase visual diversity while maintaining the views you already treasure.

  • They clean our water.

    Vegetated buffers are effective at removing pollutants from water. They slow the flow of surface water run-off and trap pollutants like nitrogen by giving it time to sink into the soil. From there, the plant roots absorb and transform the nitrogen into an essential nutrient for growth. By periodically trimming branches or removing leaves and composting them, you take nitrogen out of the systems and safely reapply it where it is needed.

How do vegetated buffers Save Our Seagrass?

When your buffer decreases nitrogen runoff

It is as easy as

  • The nitrogen will not fuel algal and phytoplankton blooms.

    Epiphytes on eelgrass leaves will remain under control.

  • Without blooms interrupting the sunlight, eelgrass can photosynthesize without competition.

  • The excess nitrogen also will not be incorporated into the eelgrass tissues. This will promote better structural integrity of the plant, making it resilient to other threats.

When You Create Your Buffer

  • Keep it continuous.

    Gaps and paths through the buffer lessen its connectivity [2]. Create small, infrequent, vegetated pathways to ensure your buffer fulfills its purpose.

  • Prevent channeling.

    Channeling is the single greatest threat to a vegetated buffer’s effectiveness [1]. Water will naturally form grooves over time in the buffer so that it can flow better. This is antithetical to our purpose so we must take steps to avoid it. Slower water flow, thick vegetation, and maintenance will ensure a successful buffer.

  • Consider the slope.

    Nitrogen is effectively filtered out of the water when the water movement is slow and retention time is high [1]. When you create your buffer, understand that steeper slopes will require more careful planning. A slope of less than 15% is will allow for adequate retention time without additional consideration.

  • Think about the width.

    The width of a buffer is measured perpendicular to the water body, starting at the side closest to the water body and measured landward. Nitrogen removal efficiency of a buffer increases asymptotically with buffer width [3]. Widths recommended to filter out nitrogen range from 25 - 150 m [4, 5]. Choose your width based on the slope of your buffer area and soil type.

  • Know your soil type.

    Sandy, highly-permeable soils, such as the soil found on Fishers Island, allow water to move rapidly both horizontally and vertically [6, 1]. In this soil type it is essential to have plants with deep roots to catch the nitrogen that is sinking into the soil as well as wide buffers to slow the horizontal path of the polluted water.