LIVING SHORELINE UPDATE 07/23/2011
by Bill McGrath
Photo taken 7/22/2011
I took an inventory of the living shoreline yesterday afternoon and again this morning. At this point, out of the 2400 plants that were planted, 470 survived. The ones that survived are extremely healthy and vigorous (see above photo). So much so, that it is very doubtful that any future storm could destroy them. So, from that point of view it is a success. The plants are now 16” to 20” tall. Most of the ones that didn't make it through the storms in June were covered over with too much sand to survive. Only a very small percentage were actually washed away. We have tweaked our design so this should not happen in future phases.
The 470 plants that are thriving there now have rhizome roots that will grow under the sand and spread out over the winter. In the spring you should see new sprouts coming up to fill in the bare spots. So, although we are only 20% successful, eventually nature will make us 100% successful. This is a “learn as you go” project for us and anyone else that wants to plant a living shoreline in these conditions. We are sort of blazing the trail here by trial and error.
In some areas of the country this species (spartina alterniflora) is considered an aggressive, invasive nuisance that is very difficult to eradicate. A single plant will spread into a circular clone, clones coalesce to form stands or meadows. Let’s hope that happens here.
A similar type of rhizome plant that is also very aggressive is the common reed (phragmites australis) . You will see it growing on both sides of the Allen Road Boardwalk where it is aggressively taking over the American Beach Grass (Ammophila breviligulata). Reaearch has shown that Phragmites rhizomes can spread as much as 80 to 100 feet per year.
The above drawing shows how the rhizomes are expanding under the Coir matting we laid down that is now buried under 7 to 10 inches of sand. As you can see, it is highly doubtful that a storm would rip these out after all these rhizomes are intertwined under the Coir matting.
It’s only a matter of time (3 to 5 years) before the entire 12 ft. by 200 ft. will be completely covered with vegetation. The benefits to the environment will be:
· Sucking up the harmful nitrogen runoff before it gets a chance to further degrade Barnegat Bay.
· Stopping the erosion of Allen Road Beach.
· Trapping sand from the littoral drift before it ends up in Amherst Inlet.
· They support microorganisms that neutralize pollutants found in water.
· They support a number of fragile benthic and marine life.
BSHCA is looking into the next phase of our living shoreline which may begin this summer or fall. The next phase will involve planting Spartina patens between our existing living shoreline and the scarping (cliff area). This area is shown in the photo below:
Photo taken 7/22/2011
Spartina patens is also a very aggressive cordgrass similar to Spartina alterniflora that we previously planted. Spartina patens grows better at a slightly higher elevation than the Spartina alterniflora. The site we have chosen in the photo above is perfectly suited for the Spartina patens. Also, this area is more protected from the onslaught of an occasional nor’easter.
We plan on stabilizing the scarping on the right side of the photo with the following native salt tolerant bushes:· Bayberry (Myrica pensylvanica)
· Marsh Elder (Iva frutescens)
· Grounsel Bush (Baccharis halimifolia)
