|
Vegetated
Phosphorus Buffer Strips
What Are They?
Vegetated Phosphorus Buffer Strips are areas of
natural vegetation which have been left undisturbed or are
replanted to naturally existing species. These vegetative buffer
strips are composed of trees, shrubs, bushes and a thick duff
layer (pine needles, bark mulch, etc.)
Why Do We Need Them?
Where there are humans, there is nutrient
pollution. The way we live tends to over-nourish and pollute our
environment. Fertilizers wash down over our carefully graded lawns
directly to the lake. The oils and greases from our cars are
rinsed off our driveways and roads down to the lake. We rest and
play along the lake and our foot traffic tramples the vegetation.
We park our cars and launch our boats as close as possible to the
lake – our heavy vehicles compact the earth until its as hard and
impenetrable as asphalt. Our lifestyles are hurting the lake.
Vegetated buffers provide a filter and percolation
area for the runoff that comes from our home and play areas. The
vegetation in the buffer uses the nutrients carried on the
stormwater as fertilizer. If the nutrients reach the lake, the
aquatic plants will use them and an algae bloom can occur.
Vegetated buffers are designed so that nutrients
are used by the land vegetation rather than by lake algae.
If you own waterfront property, the water quality
of the lake directly impacts you. If water quality deteriorates,
the value of your property decreases. Boating and swimming through
pond scum becomes less attractive. Fish populations can decline or
be killed off completely.
Where Should Buffers Be Located?
Vegetated buffers need to be placed between people
and the lake. We need to filter the stormwater runoff from our
houses, garages, driveways, roads (both paved and gravel), and
road ditches through flat vegetated areas. Lakeside parking areas
and playing fields should drain through a buffer too.
Equally important are the streams which flow into
the lake. The also need to be protected by leaving vegetated
buffer strips next to them.
Take Advantage of Natural Features:
- Leave depressions and
irregularities in your lawn. Don’t grade it to drain directly
into the lake.
- Don’t mow down to the edge of
the lake. Leave as much shrub and tree growth as possible
between the lawn and the lake.
- If you have flat wet spots on
your property, use them. Deliberately filter roof, driveway and
road runoff water through them. Don’t mow these areas – let them
grow up naturally.
Reduce The Impact You’re Making Now:
Planting A Vegetated Buffer
Composition:
Select a variety of trees, shrubs and ground covers to be used in
your buffers. All of these types of plants should be included
because in combination they take up the most water and nutrients.
To make the best choice, look at what is already growing in your
area and try to replace it.
In areas where a modest view of the lake is
desired, the predominant planting can be shrubs. Keep the openings
in the tree canopy small. When you eliminate trees you can also
reduce the quality of the buffer for deflecting raindrops and
taking up nutrients.
The natural duff layer that occurs in a forest
needs to be replaced also. A thick layer of mulch material such as
bark mulch can be used. In a pinch a grass mix with good hay mulch
will temporarily protect the area between the trees and the
shrubs.
Width:
Buffers range in width from 25 feet to 250 feet. Do the best you
can to make it as wide as possible.
Grading:
In general,
leave the buffer as irregular as possible. However, if water is
channelizing through it in a small stream or ditch, this should be
be changed. Water must flow through the buffer as sheet flow
(think of it as a thin film of water only about ¼ and inch deep at
most) for the buffer to be able to treat stormwater runoff.
If the site previously had a lot of foot or vehicle
traffic, the soil will need to be loosened up before planting can
occur. Plants can’t grow in soil that is too compacted.
Footpaths: Foot traffic to the lake through the
buffer should be limited to a winding path 4 to 6 feet wide at the
maximum. Stabilize the footpath with bark mulch, etc.
Protection and Maintenance:
- Don’t allow vehicles to cross the buffer.
- Restrict cuttings and thinning of vegetation
in the buffer as much as reasonable possible. Some cutting is
vital to preserve the health of the forest.
- Inspect the buffer annually and repair
channelization and erosion problems.
- Don’t rake the duff layer – leave it
undisturbed.
Planting Suggestions:
- Trees
- Deciduous
- Red Maple (wet areas)
- Sugar Maple
- Silver Maple
- Norway Maple
- Littleleaf Linden
- Green Ash
- Crabapple
- Red Oak
- Paper Birch
- Honey Locust
- Evergreen
- Red Pine
- White Pine
- Austrian Pine
- White Cedar
- Eastern Hemlock
- Shrubs
- Arrowood
- Korean Spice Vibernum
- Doublefile Vibernum
- Cranberry Bush
- Forsythia
- Honeysuckle
- High Bush Blueberry
- Red Twig Dogwood
- Grey Dogwood
- Serviceberry
- Rugosa Rose
- Autumn Olive
- Winterberry
- Bayberry
- Spiraea
- Lilacs
- Potentilla
- Juniper
- Barberry
- Burning Bush
- Rhododendron
- Azalea
- Vines and Groundcover
- Lowbush Blueberry
- Honeysuckle
- Bittersweet
- Virgina Creeper
- Daylily
- Hosta
- Crown Vetch Ferns
Source: Portland (Maine) Water District |
