PAGE 19 GREG BERMAN COASTAL DUNES FENCING AND SEA GRASS 052211
Hi David,
I think we've chatted a couple of times about the potential of such a design and some of the limitations / side effects. Erosion at this site is well documented, but having some fine scale "before" data would be useful if you can actually get one of these things permitted. Any luck getting a neighborhood organization together?
Also, I'd recommend clums as opposed to seeds for beachgrass, although it's getting late in the season for that. Check out the website below as there are many more choices for coastal banks than just beachgrass.
http://www.mass.gov/czm/coastal_landscaping/dune.htm
-Greg
__________________________
gberman@whoi.edu
508-289-3046
WoodsHole Sea Grant Program
193 Oyster Pond Road, MS #2,
Woods Hole, MA 02543-1525
gberman@barnstablecounty.org
508-375-6849
Cape Cod Cooperative Extension
PO Box 367
Barnstable MA 02630-0367
Marine Extension Bulletin
Woods Hole Sea Grant & Cape Cod Cooperative Extension
Protection & Restoration
Coastal Dune
Using ‘Cape’ American Beachgrass & Fencing
December 2008
The Origin of
Cape American Beachgrass
The term ‘Cape’ A m e r i c a n b e achgrass, in place of
simply American beachgrass, is used extensively
throughout this bulletin. The USDA Soil Conservation
Service (now the Natural Resources Conservation
Service) tested a collection of American beachgrass
which performed extremely well on sand dunes along
the oceanfront. Named after its place of origin, Cape
Cod, Massachusetts, it was released to the commercial
market in 1971. ‘Cape’ is considered the industry
standard and has proven to out-perform all other
varieties for conservation applications from Maine
to North Carolina (USDA, NRCS, 2006).
Table of Contents
Two Hundred Years of Planting ‘Cape’
American Beachgrass on Dunes 1
Planning Dune Restoration: Imported
Sand or Sand Fence & Vegetation 2
Survival of ‘Cape’ American Beachgrass 11
Preserving Shorebird Habitat 11
Permitting 12
Potential Adverse Considerations of
Dune Building and Restoration Permits 12
Management of Pedestrian Traffic 13
in Heavy Use Areas
Acknowledgements 14
Additional Resources 14
References 15
This bulletin addresses restoration of the dynamic frontal coastal sand dune system with
sand fencing and ‘Cape’ American beachgrass. Other typical Northeast area dune plants,
such as Rosa Rugosa, Bayberry, and Beach Plum occupy more stable secondary and backdune
areas (Clark and Clark, 2008).
By Jim O’Connell
Woods Hole Sea Grant & Cape Cod Cooperative Extension
Edited by Jeffrey Brodeur, Woods Hole Sea Grant
Coastal Dune Protection & Restoration
1
Two Hundred Years of Planting ‘Cape’ American
Beachgrass for Dune Stabilization
In 1714, after clearing thickly forested areas of the
Province Lands for fuel, fence posts, fish weirs, and
burning for croplands, colonists recognized that lack
of dune vegetation created blowing sand that was
threatening Provincetown and Provincetown Harbor,
and they began planting beach grass and placing
pine branches to stabilize the dunes (Knutson and
Finkelstein, 1987.) In 1904, Massachusetts hunters
introduced ‘Cape Cod Grass,’ brought from New
England, to the Outer Banks of North Carolina. Today,
sources of ‘Cape’ American beachgrass exist from Massachusetts
to North Carolina.
The beneficial functions of coastal dunes result from
their ability to move and change shape and supply a
reservoir of sand to the fronting beach during coastal
storms. Dunes and beaches dissipate storm wave energy
— minimizing effects to landward areas — in an
interaction known as dynamic equilibrium.
Sand dunes provide unique wildlife habitat. Dunes also
act as a barrier to storm surges and flooding, protecting
landward development and limiting storm wave effects
on landward coastal resources. During storms, coastal
dunes erode and nourish fronting and downdrift
beaches and nearshore sand bars. Sand bars, beaches
and dunes interact within the larger coastal landform
system, each exchanging sand while changing form
and shape — an interaction that dissipates storm wave
energy. As the storm diminishes and waves become less
steep, nearshore sand bars migrate landward and weld
onto the beach. Finer-grained sand is then wind-blown
back into the dune area to naturally rebuild the dunes.
However, the natural dune-rebuilding process can
take several years, and it may be desirable to rebuild a
storm-eroded dune quicker than natural processes.
Why are frontal coastal dunes so
important? Coastal dunes:
• Provide landward areas by acting as a
barrier to storm surge and flooding
• Provide significant wildlife habitat
• Provide a reservoir of sand that
nourishes eroding beaches and feeds
nearshore sand bars during storms
Figure 1. Natural and artificially stabilized dunes provide protection
to landward development and limit storm impacts to landward coastal
resources.
2
To naturally rebuild a dune, it is important to initially
determine whether there is sufficient volume of windblown
sand available. Nearby accumulation around
sand fences or the general condition of adjacent dunes
can indicate availability of wind-blown sand. For example,
moderately sized 3’ to 8’ or higher dunes in the
interdune or back dune areas, with undulating sand
surfaces and moderate to dense vegetation, would suggest
available wind-blown sand.
If wind-blown sand is available, install sand fence and
plants, based on a sketch of the area. If not, import
clean sand of compatible grain size to build the dune.
After the sand is shaped, sand fencing and plantings
can take place.
Dune Rebuilding with Imported Sand
Through experimentation at their nearly five-mile long
beach, the Duxbury Beach Reservation, Inc., in Massachusetts
discovered a method to rebuild an artificial
dune with imported quarry sand that is also appealing
to shorebird habitat. The organization covered the
quarry sand with approximately six inches of native
dune sand, then planted vegetation on the natural sand
veneer to create a natural appearing dune. (Figures
2-5, DBR Management Plan, 2003.)
The native dune sand was obtained from a landward,
more stable, dune area land and the borrow area subsequently
filled with quarry sand and recovered with
native sand.
It is interesting to note that the Duxbury Beach Reservation,
Inc. is now nourishing/rebuilding the backside
of frontal dunes, not the eroded frontal dune scarp.
Planning Dune Restoration:
Imported Sand or Sand Fence & Vegetation
Figure 2. Building a dune with imported quarry sand (Duxbury Beach,
Mass.).
Figure 3. Covering quarry sand with natural dune sand.
Figure 4. Planting the artificial dune with beachgrass.
Before beginning a dunes restoration
project, check with your local conservation
commission. See “Permitting”on page 12.
3
After many years of rebuilding the eroded frontal dune
scarp, only to have sand erode during the next moderate
storm, members realized that dune rebuilding was
taking place too far seaward for protection and longevity.
The dune was frequently inundated and eroded by
storm wave uprush. Natural processes were suggesting
a more landward location optimum for survival of the
frontal dune. That optimum landward dune location
is often landward of the seasonal average storm tide
elevation. This elevation can generally be recognized
by observing the landward toe of other frontal dunes
along that section of beach.
Thus, the procedure now for rebuilding frontal dunes
on Duxbury Beach following storms is to rebuild the
backside of the frontal dune, not the seaward side. This
approach works with landward migrating barrier beach
processes.
Another example of rebuilding a frontal dune with
trucked-in sand and the installation of sturdy sand
drift fences can be seen in Figure 6 in Brewster, Massachusetts.
Minor renourishment took place following
initial construction and the dune continues to provide
storm and flood protection to the landward dwellings.
It should be noted, however, that this dune restoration
project was on the immediate updrift side of a stone/
riprap groin so the beach was wider in that particular
location.
Begin dune building farthest landward from mean
high water as possible.
Natural vegetated coastal dunes are found a specific
distance landward of mean high water. That distance is
based primarily on the landward limit and frequency of
seasonal storm tides and wave inundation up the beach
face, because storm tides and waves prevent vegetation
from growing.
Plant vegetation at least 100 feet or greater landward
of mean high water.
Less frequent storm waves at this distance allows windblown
sand time to build dune volume and for the roots
of stabilizing dune vegetation to grow. If a 100-foot
buffer is not possible, begin building a dune the farthest
possible distance landward from mean high water,
landward of the average seasonal storm inundation area.
Adjacent seaward dune vegetation generally indicates
the average seasonal storm tide limits.
Sand Fences vs. ‘Cape’ American Beachgrass
Sand fences initially trap higher volumes of sand than
‘Cape’ American beachgrass alone. ‘Cape’ American
beachgrass traps little sand during the first growing
season. Once established however, ‘Cape’ American
beachgrass traps sand at a rate comparable to multiple
sand fences (Knutson, 1980).
Adding spurs to a straight sand fence, building zigzag
fence configurations, or perpendicular or oblique configurations
do not measurably improve long-term fence
performance, and increases construction costs (Knutson,
1980; Miller, et al, 2001.)
Figure 5. Artificially built dune naturally revegetating.
Figure 6. An artificial dune 18 months after construction.
4
In experiments on Cape Cod, planted dunes produced
lower and wider dunes than fence-built dunes (Knudson,
1980). Gently sloping, wider seaward-facing
dunes are less prone than steep slopes to wave-induced
scarping and loss of sand from storms.
Rebuilding a frontal dune
STEP 1: Draw a sketch of the dune restoration
area
A sketch can be a simple drawing based on visual observations
along with on-the-ground measurements of
the dune restoration area made using a tape measure.
A sketch could also be made on an aerial photo or satellite
image. If sufficient funds are available, a survey
with engineering drawings can be obtained, however,
the expense may not be justified, or necessary, for
smaller projects.
On the sketch, draw the locations of sand fencing and
areas for planting dune vegetation, and measure the
linear length of fence and numbers of culms (a culm
is one single plant stem) desired, based on the plant
spacing chosen (see Plant Spacing in Step 3.)
Follow this same approach for 18”, 24” or 36” oncenter
culm planting.
STEP 2: Install sand/snow fence in specific location.
Sand fencing is used to both capture wind-blown sand
to build a dune and also to control pedestrian traffic
and keep people off the fragile dune vegetation.
Posts
Install sand fence posts at or within several feet seaward
of the toe of the dune scarp. If the dune is high
and the seaward dune scarp is not too steep, a fence
could be installed partway up the seaward dune face
to add volume to the existing dune. The posts should
be buried several feet into the sand to withstand occasional
small wave energy—minimum depth of 4’ is
optimum. Shallow posts could by dislodged easily by
strong winds or waves. Posts to hold the fencing range
from metal garden stakes, 2x4 posts, 4x4 posts, and 6”
to 8” round timber piles. 2x4 posts should be installed
with the narrow (2”) end facing seaward to minimize
wind and wave effects on its stability.
Various size posts can be used. The diameter of the
post depends on whether the site is located in a high
energy area where the fence may be subject to wave or
significant wind action, and also the amount of funds
available. If it is expected that the site will be inundated
by waves, larger size posts (4x4 or 6x8 round piles)
should be considered with adequate depth embedment.
Attach the initial sand/snow fence to the posts with
1.5” to 2” galvanized staples, attaching the fence wire
to the post, or nail the fence slat directly to the post.
Figure 7. Ted Keon, Director of Coastal Resources for Chatham, Mass.,
uses a shovel for larger size holes for 6x8 poles while project manager Tim
Friary looks on.
Installing initial sand fencing or plantings
too close to the sea will result in the
capture of wind-blown sand at the
extreme seaward portion of the beach
berm, preventing the sand from reaching
and building the existing eroded
foredune. This will subject the new
fence and plants to more frequent storm
inundation and potential loss. Begin dune
restoration as far landward as possible!
5
Figure 8. Using an excavator to dig larger size holes for 6”to 8” poles,
Duxbury Beach, Mass.
Figure 10. Installing 6” piles for a double row of slat style fence.
Figure 13. Experienced sand fence installers Joe Grady and Dick Sjostedt
attach fencing to posts. The snow fence is being held taut by a crow bar
while a 2” galvanized staple is hammered into the post loosely attaching
the snow fence ‘wire’ to the post.
Figure 9. Fence arrives on Duxbury Beach, Mass. in 50’ rolls.
Figure 11. Fence is laid-out.
Figure 12. Fence is attached to 6” diameter posts.
Figure 14. A wire is wrapped around the back of the post and is attached
to the sand fence wire approximately 8” to either side. This adds support
to the fence under strong wind conditions. A loose attachment allows the
fence wire to slide and move to prevent breakage as wind shakes the fence.
Wire wrapped around the back of the post
Fence
support
wire
2.5” staple
6
Sand Fence Varieties
There are a variety of sand fence materials including
wood, plastic, polyethylene, and metal. There are
also many varieties and sizes of sand fencing, from the
typical slat-type sand/snow fencing (Figure 15), to 2x3
vertical and horizontal fence members.
Regardless of sand fence slat size, a 50-50 ratio of open
space to slats spacing between vertical members appears
to perform similarly in terms of sand volume capture.
Larger sizing of slats or posts (i.e. 2x3 slats and 6”
Figure 15. Sand/snow fence held to 2x4 posts with tie-wraps, an alternate
method of installation.
posts), or having two parallel fence rows may withstand
small wave action, but adds to overall expense.
Begin landward and over time build the existing foredune
seaward in incremental steps. As one sand fence
fills approximately two-thirds high, install another
fence slightly seaward on the newly deposited sand
(Figure 16).
Optional second initial fence
In addition to one sand fence placed at, or several feet
seaward, of the existing dune scarp, a second sand
fence could be installed one half to two-thirds up an
un-vegetated foredune slope or dune scarp. Depending
on the dune slope and size, and ability to install a
fence up the dune slope, a second fence may expedite
sand accumulation on larger dunes.
Dune building with sand fences in overwash areas
An overwash occurs when storm waves overtop the
beach berm and generally break through and flatten
dunes. The storm wave uprush does not return to sea
but continues landward and deposits sand in a flat,
fan-shaped deposit. Overwash areas in Massachusetts
are often prime piping plover or tern habitat which are
rigorously protected by law in Massachusetts. Before
conducting any activity in an overwash area, check
with your local conservation commission.
If dunes have completely eroded, significantly
lowered in elevation, and/or overwashed, dune rebuilding
should begin approximately mid-way into
the overwash fan by installing the first sand fence,
in association with planting rows of ‘Cape’ American
beachgrass (detailed in the next section). When the
first sand fence fills approximately two-thirds high,
install another fence at the rebuilt seaward dune toe.
Continue progressively building the dune seaward by
adding sand fence ‘lifts’ (Figure 16).
Dunes generally grow towards the direction of maximum
sand source. In Massachusetts, if a source is
available, sand will be blown from the prevailing
north-northwest direction in winter, and south-southwest
direction in summer. Predominant east-northeast
winter storms will move sand during brief winter
storms. Because dune restoration generally takes place
Begin dune building and planting as far
landward as possible, as installing initial sand
fencing or plantings too far seaward will:
• Capture wind-blown sand at that more
seaward location on the beach berm
and prevent that sand from reaching
and building the existing eroded foredune
leaving it vulnerable
• Subject the new, more seaward fence and
plants to more frequent storm inundation
and potential loss
7
Figure 17. Sturdy sand drift fence made of 2x3 vertical and horizontal
members, with 6” diameter posts.
Figure 18. Double row of sturdy sand drift fence — made of 2x3 vertical
and horizontal rows with 6” diameter posts which are partially buried
when installed. This style of fence is generally used in areas of small waves
or ice.
Figure 16. Building a dune through sand accumulation by installing additional sand fences, as previousy installed fence fills to approximately two-thirds.
A series of four sand fence lifts is shown (from Savage and Woodhouse, 1969, in ACOE,1984).
0 months
2 months
16 months
40 months
68 months
Ocean
100 120 140 160 180 200 210 240 260
30 40 50 60 70 80
Feet
Meters
Distance from base line
Elevation above MSL (mean sea level)
0
2
4
6
8
20
10
12
16
18
14
0
1
2
3
4
5
6
Feet
Meters
Sand fence “lifts”
8
on the seaward dune scarp (which gets eroded during
a coastal storm) and the landward dunes generally
remain vegetated, the primary sand source is generally
from the seaward direction, i.e., the beach. Some
volume of sand, however, will blow from the prevailing
west wind direction and build the backside of the
dune.
STEP 3: Planting ‘Cape’ American Beachgrass
‘Cape’ American beachgrass (Ammophila breviligulata)
is the dominant dune building plant along the North
Atlantic Coast from Maine to North Carolina and along
the Great Lakes (Knutson and Finkelstein, 1987).
The almost perfect performance and ease of establishment
of ‘Cape’ American beachgrass has escalated this
plant to being literally the only species extensively
planted on coastal sand dunes — particularly the frontal
dune — from Maine to North Carolina (Miller and
Skaradek, undated, NRCS, Cape May Plant Materials
Center).
Plant Spacing
‘Cape’ American beachgrass is generally planted 12”,
18”, 24”, or 36” on-center, in a minimum, if possible,
of 10 parallel staggered rows. Plant spacing depends
on the desired location of maximum sand accumulation
and elevation. Closer spaced plants capture
sand quicker. Spacing is based on number of plants
Figure 19. Planting ‘Cape’ American beachgrass requires only a pogo-type
hole poker (any pole or stick several feet long will do), and culms
of beach grass (100 culms in a bundle as shown). Note the horizontal bar
on the pogo stick is approximately 8” inches up from the bottom for ease
of ensuing proper depth of the hole. Makai O’Connell planting beachgrass
on Duxbury Beach, Mass.
Figure 20. Individual culms are generally planted 8” to 10” deep with
two or three culms per hole. A culm is a single plant, often with two stems.
available and the presence or absence of protected
shorebird habitat. Less dense plantings are generally
required in shorebird habitat areas, generally 36” oncenter
culms.
Estimating Plant Numbers
Calculate the square footage of the area to be planted.
Determine the plant spacing desired, e.g. 12”, 18”, 24”,
or 36”. Recall that more dense plant spacing, e.g. 12”,
traps more sand. Make sure that the highest density of
beachgrass plant spacing is where the highest volume
of sand is desired.
Example: If the area to be planted is 10’ x 10’ = 100
square feet:
• 1 plant hole per square foot = 100 plant holes
• 3 culms per hole = 300 culms of beach grass are
needed.
Due to the dense configuration of 12”
spacing, one or two culms per hole can be
sufficient, rather than the suggested two
to three culms per hole for wider spacing.
9
Planting Guidelines
Rapid dune stabilization or steep slopes--
Plant
two or three culms per hole at 12” to 18” spacing.
Rare, threatened or endangered shorebird (e.g. piping
plover) habitat areas --
Planting any vegetation
will be significantly limited — generally 36” plants
on-center is required — if planting is allowed at all.
In Massachusetts, maps of potential and actual rare
species habitat are available through your local conservation
commission.
If your dune restoration project is within a habitat, a
written opinion from the Massachusetts Division of
Fisheries and Wildlife’s Natural Heritage and Endangered
Species Program is required before authorization
for restoration is granted. They will determine whether
your project will have a short or long-term impact on
rare wildlife habitat.
Maximum dune width — Plant spacing densities can
be the same throughout a project area or, if space allows,
can be graduated from landward dense spacing
to gradually wider spacing moving seaward to obtain
maximum dune width (Figure 22).
Obtaining Maximum Dune Width
In North Carolina, researchers found that decreasing
the spacing of plants both landward and seaward from
the dune crest increased dune width and reduced the
seaward slope of the dune from about 10 percent to 5
percent (Savage and Woodhouse, 1968).
As shown in Figure 22, the most dense plant spacing
are in the landwardmost location, with decreasing plant
spacing or density moving seaward. This method will
begin dune formation in the landwardmost area and
will grow the dune seaward, resulting in a wide stable
dune.
Keep in mind that a dune will grow in the direction of
the source of wind-blown sand. Due to the open beach
area, the source will generally be from the seaward
direction.
Planting Season: November 1 through April
Optimum planting season for ‘Cape’ American Beachgrass
from Massachusetts to North Carolina is late fall
to early spring. A cut-off date of April 1 is recommended
for more southern areas in this range (Fournier,
NRCS, undated), and April 15 for the more northern
Massachusetts areas (Tim Friary, personal communication,
2008). This seasonal constraint is due to both
weather conditions and rare shorebird nesting behavioral
disruptions. The temperature and rainfall during
the summer months are too warm and dry to support a
bare root plant (Church’s Garden’s Center, 2008).
An optimum planting time for increasing plant survival
may be early to mid-March. In addition, April 1 is
generally a planting cut-off date to avoid disruption to
piping plover nesting behavior.
STEP 4: Fertilizing
Fertilizer may easily leach through porous sand and
pollute groundwater nearby bays or estuaries causing
water quality problems. Use of slow-release fertilizer
is recommended. However, technical literature recommends
various amounts of fertilizer, as detailed below.
Properly applying fertilizer is the key to good vigorous
initial growth of newly established stands of American
Beachgrass (USDA, NRC, Plant Fact Sheet, 2006).
Fertilizer stimulates growth, increases stems and accelerates
the spread of rhizomes. Inorganic, granular
Figure 21. Planting foredune scarps is particularly important.
10
Space culms
36”
apart
Space culms
18” – 24”
apart
Space culms
12”
apart
Future dune
Figure 22. Graduated plant spacing seaward increase dune width and concentrates dune volume and height in the more densly planted area.
fertilizers high in nitrogen are best (N-P-K 30-10-0,
16-8-8 or 10-10-10). Apply no more than one pound
N/1000 square feet in a single application (USDA,
NRCS, Plant Guide, 2006).
USDA, NRCS (2006) recommends applications providing
between 30-60 lbs of nitrogen per acre annually.
Splitting applications into spring and early summer is
more effective. Spring application should be applied
at least 30 days after establishment, but not later than
April 1. Once the stand is established, the rate can be
reduced by half, or applied only when the stand appears
to be weakening.
USDA, SCS, also recommends using 600 lbs of
10-10-10 fertilizer per acre (14 lbs per 1,000 sq. ft. 30
days after planting, but not before April 1.
Cape Cod Organic Farms recommends only 100 lbs of
10-10-10 fertilizer per acre. Even this lower application
rate has resulted in a 10-fold increase in stem density
(Tim Friary, personal communication, 2008).
Cape Cod Cooperative Extension suggests using 25
to 60 lbs of nitrogen per acre annually as adequate.
Results are more effective if applied in two applications:
one in spring within 30 days of planting, but before
April 1; another application in late summer or early
fall (American Beach Grass Plant – Plant Spacing Fact
Sheet).
For the first year following planting American beachgrass,
North Carolina Sea Grant recommends applying
4 lbs of 30-10-0 or 7 lbs of 16-4-8 fertilizer per 1,000
square feet in March or April and again in September.
The second year, apply 4 lbs of 30-10-0 or 7 lbs of
16-4-8 fertilizer per 1,000 sq. ft. in March and again
in September (NC Sea Grant, 2003). Fertilize only if
necessary after two years.
STEP 5: Monitoring (optional)
Monitor through documentation of dune evolution. A
DVD explaining how to monitor dune and beach profiles,
“Dune and Beach Profiling: Training in the Use of
the Emory and O’Emory Rod Methods”, is available free
from Woods Hole Sea Grant or Cape Cod Cooperative
Extension.
STEP 6: Maintenance
Add sand lost due to storms (optional).
Replace fence and plants as needed and spread fertilizer
in second year.
11
‘Cape’ American beachgrass evolved in areas of dune
systems that experience sand accretion. Moderate
sand burial processes stimulate new plant growth,
and also bury the old leaves and vegetative materials,
thus eliminating thatch build-up and pathogen harbor
(NRCS, Cape May PMC, undated). If sufficient windblown
sand is not available at a particular site, ‘Cape’
American beachgrass may only survive for a couple of
growing seasons. More frequent maintenance and plant
replacement may be necessary under these conditions.
Incorporating seed of other dune plants into the area
may also help stabilize these sand deficit areas.
As dunes mature and advance seaward, sand accumulation
slows, depriving the established beachgrass its
Survival of ‘Cape’ American Beachgrass
needed nutrients. Often the result is a decline in the
health of plants in older stands. Over a 30-40 year
period it has been observed that throughout its native
range, American beachgrass is susceptible to decline
after six to eight years when artificially established
(Miller and Skaradek, Cape May PMC). Dunes will
advance in the direction of wind-blown sand, generally
seaward, until equilibrium is reached with seasonal
frequency of storm wave inundation.
American beachgrass has been shown to be able to
grow through at least a foot — and possibly two --
of overwash sand and survive saltwater inundation
(Knutson, 1980).
Figure 23. Preserve piping plover habitat and areas for pioneer beach and
dune vegetation growth fronting the foredune by roping off the area.
Preserving Shorebird Habitat
The area immediately fronting foredunes for 20 or so
feet seaward and overwash areas, particularly on barrier
beaches, are often prime shorebird nesting habitat,
particularly for the threatened piping plover. Piping
plovers prefer relatively flat, unvegetated or sparsely
vegetated sandy/pebble/cobble mixed sediment beach
and dune areas. Thus, foredune slopes <10:1 are critical
nesting habitat and generally are required to remain
unvegetated or, at most, planted with beachgrass at 36”
spacing. For foredune slopes between 10:1 and 6:1,
consultation with your local conservation commission
or state shorebird specialists should take place prior to
submitting an application (Notice of Intent) to conduct
dune planting.
In Massachusetts, advice should be obtained from
the Massachusetts Division of Fisheries and Wildlife’s
Natural Heritage and Endangered Species Program for
planting gently sloping foredune areas.
Preserving a 20-foot buffer zone of beach fronting foredunes
to protect prime piping plover nesting habitat,
and allowing an area for seaward pioneer vegetation
growth, particularly on barrier beaches, is advisable.
On Duxbury Beach, sand fence and temporary symbolic
fencing (orange string tied to metal posts with signs)
are maintained in order to preserve plover nesting
habitat and allow pioneer vegetation to grow seaward
These measures keep pedestrians and off-road vehicles
(ORV) out of these important areas.
12
In Massachusetts, authorization, generally a permit
known as an Order of Conditions, must be obtained
from the town conservation commission for any
activity in or adjacent to a coastal dune, including
restoration.
However, before the local conservation commission can
make a determination on issuing a permit, a written
Permitting
opinion must be obtained from the Massachusetts Division
of Fisheries and Wildlife’s Natural Heritage and
Endangered Species Program advising on the potential
short- and/or long-term impacts to protected shorebird
habitat.
Considerations
u Sand dunes will slow but not prevent erosion.
u Dunes can provide significant protection from
storm surge. But along an eroding shore storm
waves will eventually overtop or erode dunes.
u Dune restoration, while a preferred and oftentimes
effective protective measure, requires maintenance.
u If a dune or vegetation are placed father seaward
than adjacent dunes (or approximately <100’ landward
of mean high water) the plants and dune will
be subject to frequent wave inundation and potential
loss.
u Discarded Christmas trees are not effective in
maintaining a coastal dune under storm condi tions.
It has been shown that storm waves dislodge the
buried trees, rapidly removing all accumulated
wind-blown sand.
Potential Adverse Considerations
of Dune Building and Restoration
Large successful dune building projects
have been shown to:
• Change adjacent micro-climate
affecting ecology and adversely
impacting coastal plant communities
(Knutson and Finkelstein, 1987).
• Prevent barrier beach/barrier island
migration by reducing frequency of
overwash
• Lower landward areas by preventing or
reducing overwash
• Potentially have negative impact on salt
marsh vertical growth by preventing
sand transport to the landward marsh
surface
13
Management of Pedestrian Traffic in Heavy Use Areas
All-weather outdoor signs help educate and orient pedestrian
traffic out of dune areas and are available free of charge from
Woods Hole Sea Grant and Cape Cod Cooperative Extension.
Additional Resources
The following individuals are thanked for improving
the content of this bulletin: Joseph Grady, Conservation
Administrator, Town of Duxbury, Mass., and a Duxbury
Beach Reservation, Inc. Trustee; Tim Friary, owner of
Cape Organic Farm, Barnstable, Mass.; Henry Lindh,
Director, Department of Natural Resources, Eastham,
Mass.; Kate Madin and Jeffrey Brodeur, Woods Hole Sea
Grant, Woods Hole, Mass.; and, Bill Clark, Director,
Cape Cod Cooperative Extension, Barnstable, Mass.
Acknowledgements
Joe Grady is particularly acknowledged for providing
technical advice on beachgrass planting and sand
fence installation techniques developed over 30 years
of annual installation of several miles of sand fence and
coordinating the annual planting of Cape American
beachgrass on Duxbury Beach.
U.S. Department of Agriculture
Natural Resources Conservation Service
Cape May Plant Material Center
Cape May, N.J.
http://plant-materials.nrcs.usda.gov/njpmc
The Dune Book
North Carolina Sea Grant
NCSU Box 8605, Raleigh, NC 27695-8605
Ask for UNC-SG-03-03. Single copies are $5.
Copies can be downloaded from the web at:
www.ncseagrant.org
Planting and Maintaining Sustainable Landscapes
(Available through the UMass Extension Bookstore)
Cape Cod Cooperative Extension & UMass
Slobody Bldg.
101 University Drive, Suite A4
Amherst, MA 01002-2385
On-line orders: umassextensionbookstore.com
($15 + shipping)
14
REFERENCES
Clark, W.F. and Cark, R.A., 2008, Planting and Maintaining Sustainable Landscapes: A Guide for Public Officials and
the Green Industry, Barnstable County and University of Massachusetts Extension Programs, UMass Extension Bookstore,
Slobody Bldg, 101 University Drive, Ste A4, Amherst, MA 01002-2385
Duxbury Beach Management Plan, 2005, Duxbury Beach Reservation, Inc, P.O. Box 2593, Duxbury, MA 02331
Fournier, M., undated, ‘Standards for Creating and Restoring Sand Dunes: from Massachusetts to North Carolina (ed.
by Miller & Skaradek, Cape May Plant Material Center, and RPS, USDA, NRCS).
Friary, Tim, 2008, Owner of Cape Organic Farms, Barnstable, MA (beachgrass farmer).
Knudson, P.L. 1980, ‘Experimental Dune Restoration and Stabilization, Nauset Beach, Cape Cod, Massachusetts, Technical
Report 80-5, U.S. Army Coastal Engineering Research Center, Fort Belvoir, VA.
Knutson, P.L., and Finkelstein, K., 1987, Environmental Considerations for Dune Stabilization Projects, Technical Report
EL-87-2, U.S. Army Engineer Waterways Experiment Research Station, Vicksburg, Miss.
Miller, C.F. and Skaradek, W., (undated), Improving Plant Diversity in Coastal Sand Dunes, USDA, NRCS, Cape May
Plant Materials Center.
Miller, L.M., Thetford, M., and Yager, 2001, Evaluation of Sand Fence and Vegetation for Dune Building Following
Overwash by Hurricane Opal on Santa Rosa, Florida, Journal of Coastal Research, vol. 17, No. 4.
Savage, R.P., and Woodhouse, W.W. Jr., 1968, Creation and Stabilization of Coastal Barrier Dunes’, Proceedings of the
11th Conference on Coastal Engineering, Am Society of Civil Engineers, Sept.
USDA, NRCS, Plant Materials Program, 2002;2006, American Beachgrass Plant Fact Sheet.
USDA, NRCS, Cape May Plant Materials Center, Investigations into American Beachgrass Die-out at National Park Service
Unit Sandy Hook, N.J., Technology Report.
Hamer, d., Belcher, C., and Miller, C., 1992, Restoration of Sand Dunes along the Mid-Atlantic Coast, USDA, SCS,
December.
15
Design & cover photos: LianneDunn.com
All other photos: Jim O’Connell
Text pages printed on 30%
post-consumer recycled paper.
Woods Hole Sea Grant
Woods Hole Oceanographic Institution
193 Oyster Pond Road, MS #2
Woods Hole, MA 02543-1525
508.289.2398
Fax 508.457.2172
www.whoi.edu/seagrant
This document, a collaboration of the Woods Hole Sea Grant Program and Barnstable County’s Cape Cod
Cooperative Extension, should be cited as follows: Coastal Dune Protection & Restoration, Using ‘Cape’
American Beach Grass and Fencing by Jim O’Connell. 2008
Thanks, Greg-as always you offer good background. I am having difficulty finding a point around which to rally anyone in our neighborhood probably because I cannot get any action started. I am assuming that my basic logic is correct in terms of economics as in cost per foot per year. I believe that I can trap passing sand during most of the spring and summer and lose it in the winter months. Therein the idea of reducing force from a location offshore might do the trick if it is modulated and allows most of the natural flows to remain intact. I am sure that I need some recording of these motions and sand accumulations using a combination of marked locations as you have suggested and some photographic mechanism to record both normal and abnormal events as being fundamental more cost effective and covering large areas. The pictures below show the extent (2,000 linear feet x approximately 400 feet to low tide) that I believe I can monitor from my location. This picture was taken yesterday and the "S" shaped rock in the middle was almost completely submerged today-another 5-8 inches approx. Very nice build-up going into the summer 2011. I assume a marked grid in the photo and means to record data might give a decently accurate history of any sand experiment. I wish that we had tried something 20 years ago. My calculations now are that sand replenishment or nourishment is more expensive than building or rebuilding the walls and that reduced wave force (from 8-10 ft to 2-4 ft) might encourage sand accumulation from all sources available especially reducing winter losses substantially at 1/20th to 1/30th of the cost of wall reconstruction on a cost per foot per year comparison. I am having problems on all levels getting information on products, sources of the right photos or Lidar or programing details to absorb weather data on a semi automatic basis. My background and resources are just not good enough to get my act together to get people's respect and information on how to accomplish the results I need. When you add the regulatory stone walls and what I consider strong objections to messing with "Mother Nature", it becomes almost impossible to get even a reasonable experiment started. The revetments saved us, but I believe were incomplete solutions based on the regulatory standards that had been set up and still control most actions we might propose today. I spoke to a neighbor who said he might help me out with the mechanics and I will press for that. In the mean time I am having a rough time dealing with a great many unknowns. I have read your paper and am guessing that the long-shore currents run between 2.5 mph and 25 mph and that perhaps 21 % of lost sand goes off shore. For us I can guess that the amount 50% total disbursed away from us would equal 1.5 inches per year which may be significant. If the blizzard of '78 raised our beach 8-11 feet as I had estimated at the time, that compares to a loss of 5 feet over 20 years since our revetments were first built. I dream of "catching" that flow. I will keep at it. Another issue I have been dreaming of is that, if we had not built the walls at all, our berm today might be 3 or 4 feet lower at the same theoretical point due to a landward movement as it is today with base of the wall. I find that thought fascinating. In any event, I intend to keep mushing along to find the regulatory and technical means to run some off the beach protections and accumulate sand at the apex(es) of that experimental "W" shaped "wall". I think it can be accomplished without serious damage to the ecology and might help the town and others retain their beaches for a much longer time. This view below is approx 1,000 linear feet x approx 400 feet "wide" looking NE. High tide line is quite low and this equates to approx 30 inches or more above where it has been at it's lowest since March of 2010. If you can suggest how I may find support for these activities, I would be very grateful. Thanks, again. David
In a message dated 5/20/2011 11:05:25 A.M. Eastern Daylight Time, gberman@barnstablecounty.org writes: Hi David,
I think we've chatted a couple of times about the potential of such a design and some of the limitations / side effects. Erosion at this site is well documented, but having some fine scale "before" data would be useful if you can actually get one of these things permitted. Any luck getting a neighborhood organization together?
Also, I'd recommend clums as opposed to seeds for beachgrass, although it's getting late in the season for that. Check out the website below as there are many more choices for coastal banks than just beachgrass.
http://www.mass.gov/czm/coastal_landscaping/dune.htm
-Greg
__________________________
gberman@whoi.edu
508-289-3046
WoodsHole Sea Grant Program
193 Oyster Pond Road, MS #2,
Woods Hole, MA 02543-1525
gberman@barnstablecounty.org
508-375-6849
Cape Cod Cooperative Extension
PO Box 367
Barnstable MA 02630-0367
-----Original Message-----
From: DCross180@aol.com [mailto:DCross180@aol.com]
Sent: Tue 5/17/2011 11:57 AM
To: Greg Berman
Subject: Re: Please see attached Word document. RSVP as soon as possible.
Thanks, Greg
Got it.
Will fwd to my neighbors.
I am interested in finding resources of sea grass seeds and plantings? for
our bluff.
Please let me know what comments you have on my e-mail.
The photos would not send on the attached letter.
That is why I placed them in the e-mail body. They just show sand movement
photo methodology so far.
David
401-751-6425
I think we've chatted a couple of times about the potential of such a design and some of the limitations / side effects. Erosion at this site is well documented, but having some fine scale "before" data would be useful if you can actually get one of these things permitted. Any luck getting a neighborhood organization together?
Also, I'd recommend clums as opposed to seeds for beachgrass, although it's getting late in the season for that. Check out the website below as there are many more choices for coastal banks than just beachgrass.
http://www.mass.gov/czm/coastal_landscaping/dune.htm
-Greg
__________________________
gberman@whoi.edu
508-289-3046
WoodsHole Sea Grant Program
193 Oyster Pond Road, MS #2,
Woods Hole, MA 02543-1525
gberman@barnstablecounty.org
508-375-6849
Cape Cod Cooperative Extension
PO Box 367
Barnstable MA 02630-0367
Marine Extension Bulletin
Woods Hole Sea Grant & Cape Cod Cooperative Extension
Protection & Restoration
Coastal Dune
Using ‘Cape’ American Beachgrass & Fencing
December 2008
The Origin of
Cape American Beachgrass
The term ‘Cape’ A m e r i c a n b e achgrass, in place of
simply American beachgrass, is used extensively
throughout this bulletin. The USDA Soil Conservation
Service (now the Natural Resources Conservation
Service) tested a collection of American beachgrass
which performed extremely well on sand dunes along
the oceanfront. Named after its place of origin, Cape
Cod, Massachusetts, it was released to the commercial
market in 1971. ‘Cape’ is considered the industry
standard and has proven to out-perform all other
varieties for conservation applications from Maine
to North Carolina (USDA, NRCS, 2006).
Table of Contents
Two Hundred Years of Planting ‘Cape’
American Beachgrass on Dunes 1
Planning Dune Restoration: Imported
Sand or Sand Fence & Vegetation 2
Survival of ‘Cape’ American Beachgrass 11
Preserving Shorebird Habitat 11
Permitting 12
Potential Adverse Considerations of
Dune Building and Restoration Permits 12
Management of Pedestrian Traffic 13
in Heavy Use Areas
Acknowledgements 14
Additional Resources 14
References 15
This bulletin addresses restoration of the dynamic frontal coastal sand dune system with
sand fencing and ‘Cape’ American beachgrass. Other typical Northeast area dune plants,
such as Rosa Rugosa, Bayberry, and Beach Plum occupy more stable secondary and backdune
areas (Clark and Clark, 2008).
By Jim O’Connell
Woods Hole Sea Grant & Cape Cod Cooperative Extension
Edited by Jeffrey Brodeur, Woods Hole Sea Grant
Coastal Dune Protection & Restoration
1
Two Hundred Years of Planting ‘Cape’ American
Beachgrass for Dune Stabilization
In 1714, after clearing thickly forested areas of the
Province Lands for fuel, fence posts, fish weirs, and
burning for croplands, colonists recognized that lack
of dune vegetation created blowing sand that was
threatening Provincetown and Provincetown Harbor,
and they began planting beach grass and placing
pine branches to stabilize the dunes (Knutson and
Finkelstein, 1987.) In 1904, Massachusetts hunters
introduced ‘Cape Cod Grass,’ brought from New
England, to the Outer Banks of North Carolina. Today,
sources of ‘Cape’ American beachgrass exist from Massachusetts
to North Carolina.
The beneficial functions of coastal dunes result from
their ability to move and change shape and supply a
reservoir of sand to the fronting beach during coastal
storms. Dunes and beaches dissipate storm wave energy
— minimizing effects to landward areas — in an
interaction known as dynamic equilibrium.
Sand dunes provide unique wildlife habitat. Dunes also
act as a barrier to storm surges and flooding, protecting
landward development and limiting storm wave effects
on landward coastal resources. During storms, coastal
dunes erode and nourish fronting and downdrift
beaches and nearshore sand bars. Sand bars, beaches
and dunes interact within the larger coastal landform
system, each exchanging sand while changing form
and shape — an interaction that dissipates storm wave
energy. As the storm diminishes and waves become less
steep, nearshore sand bars migrate landward and weld
onto the beach. Finer-grained sand is then wind-blown
back into the dune area to naturally rebuild the dunes.
However, the natural dune-rebuilding process can
take several years, and it may be desirable to rebuild a
storm-eroded dune quicker than natural processes.
Why are frontal coastal dunes so
important? Coastal dunes:
• Provide landward areas by acting as a
barrier to storm surge and flooding
• Provide significant wildlife habitat
• Provide a reservoir of sand that
nourishes eroding beaches and feeds
nearshore sand bars during storms
Figure 1. Natural and artificially stabilized dunes provide protection
to landward development and limit storm impacts to landward coastal
resources.
2
To naturally rebuild a dune, it is important to initially
determine whether there is sufficient volume of windblown
sand available. Nearby accumulation around
sand fences or the general condition of adjacent dunes
can indicate availability of wind-blown sand. For example,
moderately sized 3’ to 8’ or higher dunes in the
interdune or back dune areas, with undulating sand
surfaces and moderate to dense vegetation, would suggest
available wind-blown sand.
If wind-blown sand is available, install sand fence and
plants, based on a sketch of the area. If not, import
clean sand of compatible grain size to build the dune.
After the sand is shaped, sand fencing and plantings
can take place.
Dune Rebuilding with Imported Sand
Through experimentation at their nearly five-mile long
beach, the Duxbury Beach Reservation, Inc., in Massachusetts
discovered a method to rebuild an artificial
dune with imported quarry sand that is also appealing
to shorebird habitat. The organization covered the
quarry sand with approximately six inches of native
dune sand, then planted vegetation on the natural sand
veneer to create a natural appearing dune. (Figures
2-5, DBR Management Plan, 2003.)
The native dune sand was obtained from a landward,
more stable, dune area land and the borrow area subsequently
filled with quarry sand and recovered with
native sand.
It is interesting to note that the Duxbury Beach Reservation,
Inc. is now nourishing/rebuilding the backside
of frontal dunes, not the eroded frontal dune scarp.
Planning Dune Restoration:
Imported Sand or Sand Fence & Vegetation
Figure 2. Building a dune with imported quarry sand (Duxbury Beach,
Mass.).
Figure 3. Covering quarry sand with natural dune sand.
Figure 4. Planting the artificial dune with beachgrass.
Before beginning a dunes restoration
project, check with your local conservation
commission. See “Permitting”on page 12.
3
After many years of rebuilding the eroded frontal dune
scarp, only to have sand erode during the next moderate
storm, members realized that dune rebuilding was
taking place too far seaward for protection and longevity.
The dune was frequently inundated and eroded by
storm wave uprush. Natural processes were suggesting
a more landward location optimum for survival of the
frontal dune. That optimum landward dune location
is often landward of the seasonal average storm tide
elevation. This elevation can generally be recognized
by observing the landward toe of other frontal dunes
along that section of beach.
Thus, the procedure now for rebuilding frontal dunes
on Duxbury Beach following storms is to rebuild the
backside of the frontal dune, not the seaward side. This
approach works with landward migrating barrier beach
processes.
Another example of rebuilding a frontal dune with
trucked-in sand and the installation of sturdy sand
drift fences can be seen in Figure 6 in Brewster, Massachusetts.
Minor renourishment took place following
initial construction and the dune continues to provide
storm and flood protection to the landward dwellings.
It should be noted, however, that this dune restoration
project was on the immediate updrift side of a stone/
riprap groin so the beach was wider in that particular
location.
Begin dune building farthest landward from mean
high water as possible.
Natural vegetated coastal dunes are found a specific
distance landward of mean high water. That distance is
based primarily on the landward limit and frequency of
seasonal storm tides and wave inundation up the beach
face, because storm tides and waves prevent vegetation
from growing.
Plant vegetation at least 100 feet or greater landward
of mean high water.
Less frequent storm waves at this distance allows windblown
sand time to build dune volume and for the roots
of stabilizing dune vegetation to grow. If a 100-foot
buffer is not possible, begin building a dune the farthest
possible distance landward from mean high water,
landward of the average seasonal storm inundation area.
Adjacent seaward dune vegetation generally indicates
the average seasonal storm tide limits.
Sand Fences vs. ‘Cape’ American Beachgrass
Sand fences initially trap higher volumes of sand than
‘Cape’ American beachgrass alone. ‘Cape’ American
beachgrass traps little sand during the first growing
season. Once established however, ‘Cape’ American
beachgrass traps sand at a rate comparable to multiple
sand fences (Knutson, 1980).
Adding spurs to a straight sand fence, building zigzag
fence configurations, or perpendicular or oblique configurations
do not measurably improve long-term fence
performance, and increases construction costs (Knutson,
1980; Miller, et al, 2001.)
Figure 5. Artificially built dune naturally revegetating.
Figure 6. An artificial dune 18 months after construction.
4
In experiments on Cape Cod, planted dunes produced
lower and wider dunes than fence-built dunes (Knudson,
1980). Gently sloping, wider seaward-facing
dunes are less prone than steep slopes to wave-induced
scarping and loss of sand from storms.
Rebuilding a frontal dune
STEP 1: Draw a sketch of the dune restoration
area
A sketch can be a simple drawing based on visual observations
along with on-the-ground measurements of
the dune restoration area made using a tape measure.
A sketch could also be made on an aerial photo or satellite
image. If sufficient funds are available, a survey
with engineering drawings can be obtained, however,
the expense may not be justified, or necessary, for
smaller projects.
On the sketch, draw the locations of sand fencing and
areas for planting dune vegetation, and measure the
linear length of fence and numbers of culms (a culm
is one single plant stem) desired, based on the plant
spacing chosen (see Plant Spacing in Step 3.)
Follow this same approach for 18”, 24” or 36” oncenter
culm planting.
STEP 2: Install sand/snow fence in specific location.
Sand fencing is used to both capture wind-blown sand
to build a dune and also to control pedestrian traffic
and keep people off the fragile dune vegetation.
Posts
Install sand fence posts at or within several feet seaward
of the toe of the dune scarp. If the dune is high
and the seaward dune scarp is not too steep, a fence
could be installed partway up the seaward dune face
to add volume to the existing dune. The posts should
be buried several feet into the sand to withstand occasional
small wave energy—minimum depth of 4’ is
optimum. Shallow posts could by dislodged easily by
strong winds or waves. Posts to hold the fencing range
from metal garden stakes, 2x4 posts, 4x4 posts, and 6”
to 8” round timber piles. 2x4 posts should be installed
with the narrow (2”) end facing seaward to minimize
wind and wave effects on its stability.
Various size posts can be used. The diameter of the
post depends on whether the site is located in a high
energy area where the fence may be subject to wave or
significant wind action, and also the amount of funds
available. If it is expected that the site will be inundated
by waves, larger size posts (4x4 or 6x8 round piles)
should be considered with adequate depth embedment.
Attach the initial sand/snow fence to the posts with
1.5” to 2” galvanized staples, attaching the fence wire
to the post, or nail the fence slat directly to the post.
Figure 7. Ted Keon, Director of Coastal Resources for Chatham, Mass.,
uses a shovel for larger size holes for 6x8 poles while project manager Tim
Friary looks on.
Installing initial sand fencing or plantings
too close to the sea will result in the
capture of wind-blown sand at the
extreme seaward portion of the beach
berm, preventing the sand from reaching
and building the existing eroded
foredune. This will subject the new
fence and plants to more frequent storm
inundation and potential loss. Begin dune
restoration as far landward as possible!
5
Figure 8. Using an excavator to dig larger size holes for 6”to 8” poles,
Duxbury Beach, Mass.
Figure 10. Installing 6” piles for a double row of slat style fence.
Figure 13. Experienced sand fence installers Joe Grady and Dick Sjostedt
attach fencing to posts. The snow fence is being held taut by a crow bar
while a 2” galvanized staple is hammered into the post loosely attaching
the snow fence ‘wire’ to the post.
Figure 9. Fence arrives on Duxbury Beach, Mass. in 50’ rolls.
Figure 11. Fence is laid-out.
Figure 12. Fence is attached to 6” diameter posts.
Figure 14. A wire is wrapped around the back of the post and is attached
to the sand fence wire approximately 8” to either side. This adds support
to the fence under strong wind conditions. A loose attachment allows the
fence wire to slide and move to prevent breakage as wind shakes the fence.
Wire wrapped around the back of the post
Fence
support
wire
2.5” staple
6
Sand Fence Varieties
There are a variety of sand fence materials including
wood, plastic, polyethylene, and metal. There are
also many varieties and sizes of sand fencing, from the
typical slat-type sand/snow fencing (Figure 15), to 2x3
vertical and horizontal fence members.
Regardless of sand fence slat size, a 50-50 ratio of open
space to slats spacing between vertical members appears
to perform similarly in terms of sand volume capture.
Larger sizing of slats or posts (i.e. 2x3 slats and 6”
Figure 15. Sand/snow fence held to 2x4 posts with tie-wraps, an alternate
method of installation.
posts), or having two parallel fence rows may withstand
small wave action, but adds to overall expense.
Begin landward and over time build the existing foredune
seaward in incremental steps. As one sand fence
fills approximately two-thirds high, install another
fence slightly seaward on the newly deposited sand
(Figure 16).
Optional second initial fence
In addition to one sand fence placed at, or several feet
seaward, of the existing dune scarp, a second sand
fence could be installed one half to two-thirds up an
un-vegetated foredune slope or dune scarp. Depending
on the dune slope and size, and ability to install a
fence up the dune slope, a second fence may expedite
sand accumulation on larger dunes.
Dune building with sand fences in overwash areas
An overwash occurs when storm waves overtop the
beach berm and generally break through and flatten
dunes. The storm wave uprush does not return to sea
but continues landward and deposits sand in a flat,
fan-shaped deposit. Overwash areas in Massachusetts
are often prime piping plover or tern habitat which are
rigorously protected by law in Massachusetts. Before
conducting any activity in an overwash area, check
with your local conservation commission.
If dunes have completely eroded, significantly
lowered in elevation, and/or overwashed, dune rebuilding
should begin approximately mid-way into
the overwash fan by installing the first sand fence,
in association with planting rows of ‘Cape’ American
beachgrass (detailed in the next section). When the
first sand fence fills approximately two-thirds high,
install another fence at the rebuilt seaward dune toe.
Continue progressively building the dune seaward by
adding sand fence ‘lifts’ (Figure 16).
Dunes generally grow towards the direction of maximum
sand source. In Massachusetts, if a source is
available, sand will be blown from the prevailing
north-northwest direction in winter, and south-southwest
direction in summer. Predominant east-northeast
winter storms will move sand during brief winter
storms. Because dune restoration generally takes place
Begin dune building and planting as far
landward as possible, as installing initial sand
fencing or plantings too far seaward will:
• Capture wind-blown sand at that more
seaward location on the beach berm
and prevent that sand from reaching
and building the existing eroded foredune
leaving it vulnerable
• Subject the new, more seaward fence and
plants to more frequent storm inundation
and potential loss
7
Figure 17. Sturdy sand drift fence made of 2x3 vertical and horizontal
members, with 6” diameter posts.
Figure 18. Double row of sturdy sand drift fence — made of 2x3 vertical
and horizontal rows with 6” diameter posts which are partially buried
when installed. This style of fence is generally used in areas of small waves
or ice.
Figure 16. Building a dune through sand accumulation by installing additional sand fences, as previousy installed fence fills to approximately two-thirds.
A series of four sand fence lifts is shown (from Savage and Woodhouse, 1969, in ACOE,1984).
0 months
2 months
16 months
40 months
68 months
Ocean
100 120 140 160 180 200 210 240 260
30 40 50 60 70 80
Feet
Meters
Distance from base line
Elevation above MSL (mean sea level)
0
2
4
6
8
20
10
12
16
18
14
0
1
2
3
4
5
6
Feet
Meters
Sand fence “lifts”
8
on the seaward dune scarp (which gets eroded during
a coastal storm) and the landward dunes generally
remain vegetated, the primary sand source is generally
from the seaward direction, i.e., the beach. Some
volume of sand, however, will blow from the prevailing
west wind direction and build the backside of the
dune.
STEP 3: Planting ‘Cape’ American Beachgrass
‘Cape’ American beachgrass (Ammophila breviligulata)
is the dominant dune building plant along the North
Atlantic Coast from Maine to North Carolina and along
the Great Lakes (Knutson and Finkelstein, 1987).
The almost perfect performance and ease of establishment
of ‘Cape’ American beachgrass has escalated this
plant to being literally the only species extensively
planted on coastal sand dunes — particularly the frontal
dune — from Maine to North Carolina (Miller and
Skaradek, undated, NRCS, Cape May Plant Materials
Center).
Plant Spacing
‘Cape’ American beachgrass is generally planted 12”,
18”, 24”, or 36” on-center, in a minimum, if possible,
of 10 parallel staggered rows. Plant spacing depends
on the desired location of maximum sand accumulation
and elevation. Closer spaced plants capture
sand quicker. Spacing is based on number of plants
Figure 19. Planting ‘Cape’ American beachgrass requires only a pogo-type
hole poker (any pole or stick several feet long will do), and culms
of beach grass (100 culms in a bundle as shown). Note the horizontal bar
on the pogo stick is approximately 8” inches up from the bottom for ease
of ensuing proper depth of the hole. Makai O’Connell planting beachgrass
on Duxbury Beach, Mass.
Figure 20. Individual culms are generally planted 8” to 10” deep with
two or three culms per hole. A culm is a single plant, often with two stems.
available and the presence or absence of protected
shorebird habitat. Less dense plantings are generally
required in shorebird habitat areas, generally 36” oncenter
culms.
Estimating Plant Numbers
Calculate the square footage of the area to be planted.
Determine the plant spacing desired, e.g. 12”, 18”, 24”,
or 36”. Recall that more dense plant spacing, e.g. 12”,
traps more sand. Make sure that the highest density of
beachgrass plant spacing is where the highest volume
of sand is desired.
Example: If the area to be planted is 10’ x 10’ = 100
square feet:
• 1 plant hole per square foot = 100 plant holes
• 3 culms per hole = 300 culms of beach grass are
needed.
Due to the dense configuration of 12”
spacing, one or two culms per hole can be
sufficient, rather than the suggested two
to three culms per hole for wider spacing.
9
Planting Guidelines
Rapid dune stabilization or steep slopes--
Plant
two or three culms per hole at 12” to 18” spacing.
Rare, threatened or endangered shorebird (e.g. piping
plover) habitat areas --
Planting any vegetation
will be significantly limited — generally 36” plants
on-center is required — if planting is allowed at all.
In Massachusetts, maps of potential and actual rare
species habitat are available through your local conservation
commission.
If your dune restoration project is within a habitat, a
written opinion from the Massachusetts Division of
Fisheries and Wildlife’s Natural Heritage and Endangered
Species Program is required before authorization
for restoration is granted. They will determine whether
your project will have a short or long-term impact on
rare wildlife habitat.
Maximum dune width — Plant spacing densities can
be the same throughout a project area or, if space allows,
can be graduated from landward dense spacing
to gradually wider spacing moving seaward to obtain
maximum dune width (Figure 22).
Obtaining Maximum Dune Width
In North Carolina, researchers found that decreasing
the spacing of plants both landward and seaward from
the dune crest increased dune width and reduced the
seaward slope of the dune from about 10 percent to 5
percent (Savage and Woodhouse, 1968).
As shown in Figure 22, the most dense plant spacing
are in the landwardmost location, with decreasing plant
spacing or density moving seaward. This method will
begin dune formation in the landwardmost area and
will grow the dune seaward, resulting in a wide stable
dune.
Keep in mind that a dune will grow in the direction of
the source of wind-blown sand. Due to the open beach
area, the source will generally be from the seaward
direction.
Planting Season: November 1 through April
Optimum planting season for ‘Cape’ American Beachgrass
from Massachusetts to North Carolina is late fall
to early spring. A cut-off date of April 1 is recommended
for more southern areas in this range (Fournier,
NRCS, undated), and April 15 for the more northern
Massachusetts areas (Tim Friary, personal communication,
2008). This seasonal constraint is due to both
weather conditions and rare shorebird nesting behavioral
disruptions. The temperature and rainfall during
the summer months are too warm and dry to support a
bare root plant (Church’s Garden’s Center, 2008).
An optimum planting time for increasing plant survival
may be early to mid-March. In addition, April 1 is
generally a planting cut-off date to avoid disruption to
piping plover nesting behavior.
STEP 4: Fertilizing
Fertilizer may easily leach through porous sand and
pollute groundwater nearby bays or estuaries causing
water quality problems. Use of slow-release fertilizer
is recommended. However, technical literature recommends
various amounts of fertilizer, as detailed below.
Properly applying fertilizer is the key to good vigorous
initial growth of newly established stands of American
Beachgrass (USDA, NRC, Plant Fact Sheet, 2006).
Fertilizer stimulates growth, increases stems and accelerates
the spread of rhizomes. Inorganic, granular
Figure 21. Planting foredune scarps is particularly important.
10
Space culms
36”
apart
Space culms
18” – 24”
apart
Space culms
12”
apart
Future dune
Figure 22. Graduated plant spacing seaward increase dune width and concentrates dune volume and height in the more densly planted area.
fertilizers high in nitrogen are best (N-P-K 30-10-0,
16-8-8 or 10-10-10). Apply no more than one pound
N/1000 square feet in a single application (USDA,
NRCS, Plant Guide, 2006).
USDA, NRCS (2006) recommends applications providing
between 30-60 lbs of nitrogen per acre annually.
Splitting applications into spring and early summer is
more effective. Spring application should be applied
at least 30 days after establishment, but not later than
April 1. Once the stand is established, the rate can be
reduced by half, or applied only when the stand appears
to be weakening.
USDA, SCS, also recommends using 600 lbs of
10-10-10 fertilizer per acre (14 lbs per 1,000 sq. ft. 30
days after planting, but not before April 1.
Cape Cod Organic Farms recommends only 100 lbs of
10-10-10 fertilizer per acre. Even this lower application
rate has resulted in a 10-fold increase in stem density
(Tim Friary, personal communication, 2008).
Cape Cod Cooperative Extension suggests using 25
to 60 lbs of nitrogen per acre annually as adequate.
Results are more effective if applied in two applications:
one in spring within 30 days of planting, but before
April 1; another application in late summer or early
fall (American Beach Grass Plant – Plant Spacing Fact
Sheet).
For the first year following planting American beachgrass,
North Carolina Sea Grant recommends applying
4 lbs of 30-10-0 or 7 lbs of 16-4-8 fertilizer per 1,000
square feet in March or April and again in September.
The second year, apply 4 lbs of 30-10-0 or 7 lbs of
16-4-8 fertilizer per 1,000 sq. ft. in March and again
in September (NC Sea Grant, 2003). Fertilize only if
necessary after two years.
STEP 5: Monitoring (optional)
Monitor through documentation of dune evolution. A
DVD explaining how to monitor dune and beach profiles,
“Dune and Beach Profiling: Training in the Use of
the Emory and O’Emory Rod Methods”, is available free
from Woods Hole Sea Grant or Cape Cod Cooperative
Extension.
STEP 6: Maintenance
Add sand lost due to storms (optional).
Replace fence and plants as needed and spread fertilizer
in second year.
11
‘Cape’ American beachgrass evolved in areas of dune
systems that experience sand accretion. Moderate
sand burial processes stimulate new plant growth,
and also bury the old leaves and vegetative materials,
thus eliminating thatch build-up and pathogen harbor
(NRCS, Cape May PMC, undated). If sufficient windblown
sand is not available at a particular site, ‘Cape’
American beachgrass may only survive for a couple of
growing seasons. More frequent maintenance and plant
replacement may be necessary under these conditions.
Incorporating seed of other dune plants into the area
may also help stabilize these sand deficit areas.
As dunes mature and advance seaward, sand accumulation
slows, depriving the established beachgrass its
Survival of ‘Cape’ American Beachgrass
needed nutrients. Often the result is a decline in the
health of plants in older stands. Over a 30-40 year
period it has been observed that throughout its native
range, American beachgrass is susceptible to decline
after six to eight years when artificially established
(Miller and Skaradek, Cape May PMC). Dunes will
advance in the direction of wind-blown sand, generally
seaward, until equilibrium is reached with seasonal
frequency of storm wave inundation.
American beachgrass has been shown to be able to
grow through at least a foot — and possibly two --
of overwash sand and survive saltwater inundation
(Knutson, 1980).
Figure 23. Preserve piping plover habitat and areas for pioneer beach and
dune vegetation growth fronting the foredune by roping off the area.
Preserving Shorebird Habitat
The area immediately fronting foredunes for 20 or so
feet seaward and overwash areas, particularly on barrier
beaches, are often prime shorebird nesting habitat,
particularly for the threatened piping plover. Piping
plovers prefer relatively flat, unvegetated or sparsely
vegetated sandy/pebble/cobble mixed sediment beach
and dune areas. Thus, foredune slopes <10:1 are critical
nesting habitat and generally are required to remain
unvegetated or, at most, planted with beachgrass at 36”
spacing. For foredune slopes between 10:1 and 6:1,
consultation with your local conservation commission
or state shorebird specialists should take place prior to
submitting an application (Notice of Intent) to conduct
dune planting.
In Massachusetts, advice should be obtained from
the Massachusetts Division of Fisheries and Wildlife’s
Natural Heritage and Endangered Species Program for
planting gently sloping foredune areas.
Preserving a 20-foot buffer zone of beach fronting foredunes
to protect prime piping plover nesting habitat,
and allowing an area for seaward pioneer vegetation
growth, particularly on barrier beaches, is advisable.
On Duxbury Beach, sand fence and temporary symbolic
fencing (orange string tied to metal posts with signs)
are maintained in order to preserve plover nesting
habitat and allow pioneer vegetation to grow seaward
These measures keep pedestrians and off-road vehicles
(ORV) out of these important areas.
12
In Massachusetts, authorization, generally a permit
known as an Order of Conditions, must be obtained
from the town conservation commission for any
activity in or adjacent to a coastal dune, including
restoration.
However, before the local conservation commission can
make a determination on issuing a permit, a written
Permitting
opinion must be obtained from the Massachusetts Division
of Fisheries and Wildlife’s Natural Heritage and
Endangered Species Program advising on the potential
short- and/or long-term impacts to protected shorebird
habitat.
Considerations
u Sand dunes will slow but not prevent erosion.
u Dunes can provide significant protection from
storm surge. But along an eroding shore storm
waves will eventually overtop or erode dunes.
u Dune restoration, while a preferred and oftentimes
effective protective measure, requires maintenance.
u If a dune or vegetation are placed father seaward
than adjacent dunes (or approximately <100’ landward
of mean high water) the plants and dune will
be subject to frequent wave inundation and potential
loss.
u Discarded Christmas trees are not effective in
maintaining a coastal dune under storm condi tions.
It has been shown that storm waves dislodge the
buried trees, rapidly removing all accumulated
wind-blown sand.
Potential Adverse Considerations
of Dune Building and Restoration
Large successful dune building projects
have been shown to:
• Change adjacent micro-climate
affecting ecology and adversely
impacting coastal plant communities
(Knutson and Finkelstein, 1987).
• Prevent barrier beach/barrier island
migration by reducing frequency of
overwash
• Lower landward areas by preventing or
reducing overwash
• Potentially have negative impact on salt
marsh vertical growth by preventing
sand transport to the landward marsh
surface
13
Management of Pedestrian Traffic in Heavy Use Areas
All-weather outdoor signs help educate and orient pedestrian
traffic out of dune areas and are available free of charge from
Woods Hole Sea Grant and Cape Cod Cooperative Extension.
Additional Resources
The following individuals are thanked for improving
the content of this bulletin: Joseph Grady, Conservation
Administrator, Town of Duxbury, Mass., and a Duxbury
Beach Reservation, Inc. Trustee; Tim Friary, owner of
Cape Organic Farm, Barnstable, Mass.; Henry Lindh,
Director, Department of Natural Resources, Eastham,
Mass.; Kate Madin and Jeffrey Brodeur, Woods Hole Sea
Grant, Woods Hole, Mass.; and, Bill Clark, Director,
Cape Cod Cooperative Extension, Barnstable, Mass.
Acknowledgements
Joe Grady is particularly acknowledged for providing
technical advice on beachgrass planting and sand
fence installation techniques developed over 30 years
of annual installation of several miles of sand fence and
coordinating the annual planting of Cape American
beachgrass on Duxbury Beach.
U.S. Department of Agriculture
Natural Resources Conservation Service
Cape May Plant Material Center
Cape May, N.J.
http://plant-materials.nrcs.usda.gov/njpmc
The Dune Book
North Carolina Sea Grant
NCSU Box 8605, Raleigh, NC 27695-8605
Ask for UNC-SG-03-03. Single copies are $5.
Copies can be downloaded from the web at:
www.ncseagrant.org
Planting and Maintaining Sustainable Landscapes
(Available through the UMass Extension Bookstore)
Cape Cod Cooperative Extension & UMass
Slobody Bldg.
101 University Drive, Suite A4
Amherst, MA 01002-2385
On-line orders: umassextensionbookstore.com
($15 + shipping)
14
REFERENCES
Clark, W.F. and Cark, R.A., 2008, Planting and Maintaining Sustainable Landscapes: A Guide for Public Officials and
the Green Industry, Barnstable County and University of Massachusetts Extension Programs, UMass Extension Bookstore,
Slobody Bldg, 101 University Drive, Ste A4, Amherst, MA 01002-2385
Duxbury Beach Management Plan, 2005, Duxbury Beach Reservation, Inc, P.O. Box 2593, Duxbury, MA 02331
Fournier, M., undated, ‘Standards for Creating and Restoring Sand Dunes: from Massachusetts to North Carolina (ed.
by Miller & Skaradek, Cape May Plant Material Center, and RPS, USDA, NRCS).
Friary, Tim, 2008, Owner of Cape Organic Farms, Barnstable, MA (beachgrass farmer).
Knudson, P.L. 1980, ‘Experimental Dune Restoration and Stabilization, Nauset Beach, Cape Cod, Massachusetts, Technical
Report 80-5, U.S. Army Coastal Engineering Research Center, Fort Belvoir, VA.
Knutson, P.L., and Finkelstein, K., 1987, Environmental Considerations for Dune Stabilization Projects, Technical Report
EL-87-2, U.S. Army Engineer Waterways Experiment Research Station, Vicksburg, Miss.
Miller, C.F. and Skaradek, W., (undated), Improving Plant Diversity in Coastal Sand Dunes, USDA, NRCS, Cape May
Plant Materials Center.
Miller, L.M., Thetford, M., and Yager, 2001, Evaluation of Sand Fence and Vegetation for Dune Building Following
Overwash by Hurricane Opal on Santa Rosa, Florida, Journal of Coastal Research, vol. 17, No. 4.
Savage, R.P., and Woodhouse, W.W. Jr., 1968, Creation and Stabilization of Coastal Barrier Dunes’, Proceedings of the
11th Conference on Coastal Engineering, Am Society of Civil Engineers, Sept.
USDA, NRCS, Plant Materials Program, 2002;2006, American Beachgrass Plant Fact Sheet.
USDA, NRCS, Cape May Plant Materials Center, Investigations into American Beachgrass Die-out at National Park Service
Unit Sandy Hook, N.J., Technology Report.
Hamer, d., Belcher, C., and Miller, C., 1992, Restoration of Sand Dunes along the Mid-Atlantic Coast, USDA, SCS,
December.
15
Design & cover photos: LianneDunn.com
All other photos: Jim O’Connell
Text pages printed on 30%
post-consumer recycled paper.
Woods Hole Sea Grant
Woods Hole Oceanographic Institution
193 Oyster Pond Road, MS #2
Woods Hole, MA 02543-1525
508.289.2398
Fax 508.457.2172
www.whoi.edu/seagrant
This document, a collaboration of the Woods Hole Sea Grant Program and Barnstable County’s Cape Cod
Cooperative Extension, should be cited as follows: Coastal Dune Protection & Restoration, Using ‘Cape’
American Beach Grass and Fencing by Jim O’Connell. 2008
Thanks, Greg-as always you offer good background. I am having difficulty finding a point around which to rally anyone in our neighborhood probably because I cannot get any action started. I am assuming that my basic logic is correct in terms of economics as in cost per foot per year. I believe that I can trap passing sand during most of the spring and summer and lose it in the winter months. Therein the idea of reducing force from a location offshore might do the trick if it is modulated and allows most of the natural flows to remain intact. I am sure that I need some recording of these motions and sand accumulations using a combination of marked locations as you have suggested and some photographic mechanism to record both normal and abnormal events as being fundamental more cost effective and covering large areas. The pictures below show the extent (2,000 linear feet x approximately 400 feet to low tide) that I believe I can monitor from my location. This picture was taken yesterday and the "S" shaped rock in the middle was almost completely submerged today-another 5-8 inches approx. Very nice build-up going into the summer 2011. I assume a marked grid in the photo and means to record data might give a decently accurate history of any sand experiment. I wish that we had tried something 20 years ago. My calculations now are that sand replenishment or nourishment is more expensive than building or rebuilding the walls and that reduced wave force (from 8-10 ft to 2-4 ft) might encourage sand accumulation from all sources available especially reducing winter losses substantially at 1/20th to 1/30th of the cost of wall reconstruction on a cost per foot per year comparison. I am having problems on all levels getting information on products, sources of the right photos or Lidar or programing details to absorb weather data on a semi automatic basis. My background and resources are just not good enough to get my act together to get people's respect and information on how to accomplish the results I need. When you add the regulatory stone walls and what I consider strong objections to messing with "Mother Nature", it becomes almost impossible to get even a reasonable experiment started. The revetments saved us, but I believe were incomplete solutions based on the regulatory standards that had been set up and still control most actions we might propose today. I spoke to a neighbor who said he might help me out with the mechanics and I will press for that. In the mean time I am having a rough time dealing with a great many unknowns. I have read your paper and am guessing that the long-shore currents run between 2.5 mph and 25 mph and that perhaps 21 % of lost sand goes off shore. For us I can guess that the amount 50% total disbursed away from us would equal 1.5 inches per year which may be significant. If the blizzard of '78 raised our beach 8-11 feet as I had estimated at the time, that compares to a loss of 5 feet over 20 years since our revetments were first built. I dream of "catching" that flow. I will keep at it. Another issue I have been dreaming of is that, if we had not built the walls at all, our berm today might be 3 or 4 feet lower at the same theoretical point due to a landward movement as it is today with base of the wall. I find that thought fascinating. In any event, I intend to keep mushing along to find the regulatory and technical means to run some off the beach protections and accumulate sand at the apex(es) of that experimental "W" shaped "wall". I think it can be accomplished without serious damage to the ecology and might help the town and others retain their beaches for a much longer time. This view below is approx 1,000 linear feet x approx 400 feet "wide" looking NE. High tide line is quite low and this equates to approx 30 inches or more above where it has been at it's lowest since March of 2010. If you can suggest how I may find support for these activities, I would be very grateful. Thanks, again. David
In a message dated 5/20/2011 11:05:25 A.M. Eastern Daylight Time, gberman@barnstablecounty.org writes: Hi David,
I think we've chatted a couple of times about the potential of such a design and some of the limitations / side effects. Erosion at this site is well documented, but having some fine scale "before" data would be useful if you can actually get one of these things permitted. Any luck getting a neighborhood organization together?
Also, I'd recommend clums as opposed to seeds for beachgrass, although it's getting late in the season for that. Check out the website below as there are many more choices for coastal banks than just beachgrass.
http://www.mass.gov/czm/coastal_landscaping/dune.htm
-Greg
__________________________
gberman@whoi.edu
508-289-3046
WoodsHole Sea Grant Program
193 Oyster Pond Road, MS #2,
Woods Hole, MA 02543-1525
gberman@barnstablecounty.org
508-375-6849
Cape Cod Cooperative Extension
PO Box 367
Barnstable MA 02630-0367
-----Original Message-----
From: DCross180@aol.com [mailto:DCross180@aol.com]
Sent: Tue 5/17/2011 11:57 AM
To: Greg Berman
Subject: Re: Please see attached Word document. RSVP as soon as possible.
Thanks, Greg
Got it.
Will fwd to my neighbors.
I am interested in finding resources of sea grass seeds and plantings? for
our bluff.
Please let me know what comments you have on my e-mail.
The photos would not send on the attached letter.
That is why I placed them in the e-mail body. They just show sand movement
photo methodology so far.
David
401-751-6425
