Gouverneur Beach: Sand Dunes Restoration
Coastal sand dunes protect against wave damage. They store sand, often for decades or centuries, so that beaches can replenish themselves. Dunes are nature's insurance policy and human's first line of defense against storm surge. They manage the sand for beach tourism, and they provide a vital habitat for nesting sea turtles, migrating songbirds, and host of other species. A remarkable set of plants live on sand dunes. It is the unique adaptations and activities of these plants that keep sand dunes intact and provide us with an array of services.
THE RESTORATION
Why restore the sand dunes at Gouverneur?
The sand dunes at Gouverneur had degraded badly. Storms, droughts, and human trampling all contributed to the loss of vegetation. As the plants disappeared or died, the sand itself began to blow away, making it difficult for the dunes to recover and threatening the long term viability of the beach. This project is designed to replenish the sand and sustain the dunes and the beach ecosystem on which we all depend.
The sand dunes at Gouverneur had degraded badly. Storms, droughts, and human trampling all contributed to the loss of vegetation. As the plants disappeared or died, the sand itself began to blow away, making it difficult for the dunes to recover and threatening the long term viability of the beach. This project is designed to replenish the sand and sustain the dunes and the beach ecosystem on which we all depend.
APPROACH
Approach: Evaluating the Problem
In restoring the dunes we wanted to take a scientific approach, and to work with the natural ecosystem. Our first step was to observe the normal dynamics of sand movement, and to evaluate the health of the dunes and the plants.
Sand dunes have a very specific architecture, or structure, called "zonation" in scientific terms.The foredune (edge of the dune that is closest to the sea) is the most dynamic environment. It is also the harshest. Only extremely salt tolerant plants, mostly grasses and some vines can live in this zone. Not only can grasses tolerate salt, and low nutrients, they are adept at trapping sand grains that are blown onto the grass. Many grasses can tolerate being buried under sand, and for some species this stimulates them to grow which adds even more stability to the dune. But while these grasses and vines are tolerant of harsh conditions they are unable to withstand human trampling or disturbance.
The dune slope (from the strand area to the crest) is home to more vines and shrubby vegetation, which are slightly less salt tolerant, slower growing but longer lived. Finally from the crest to back dune is the zone where denser and woody plants like Cocoloba (sea grape) thrive. This habitat has higher nutrients and is often sustained by decaying vegetation (much like a tropical rain forest). However the underlying soil is sand, and this ancient habitat (also known as a legacy beach) is a key sand storage site (like money in a vault). The whole system is beautifully interconnected. The back dune plants depend on the presence of grasses to hold the sand and take the brunt of the salt. In turn the grasses rely on the long term sand storage and stability of plants like Cocoloba.
Our analysis showed that for on a third to half of Gouverneur beach, most of the fordune and crest plants were dead or missing. The grasses had been lost. Consequently the dune sand had blown away. Instead a curving dune the beach profile had flattened. Plants adapted for life in the back dunes (e.g. Cocoloba) were now forced to the "foredune" and are were doing poorly, suffering from drought, salt, and low nutrients, and many were on the brink of dying.
In restoring the dunes we wanted to take a scientific approach, and to work with the natural ecosystem. Our first step was to observe the normal dynamics of sand movement, and to evaluate the health of the dunes and the plants.
Sand dunes have a very specific architecture, or structure, called "zonation" in scientific terms.The foredune (edge of the dune that is closest to the sea) is the most dynamic environment. It is also the harshest. Only extremely salt tolerant plants, mostly grasses and some vines can live in this zone. Not only can grasses tolerate salt, and low nutrients, they are adept at trapping sand grains that are blown onto the grass. Many grasses can tolerate being buried under sand, and for some species this stimulates them to grow which adds even more stability to the dune. But while these grasses and vines are tolerant of harsh conditions they are unable to withstand human trampling or disturbance.
The dune slope (from the strand area to the crest) is home to more vines and shrubby vegetation, which are slightly less salt tolerant, slower growing but longer lived. Finally from the crest to back dune is the zone where denser and woody plants like Cocoloba (sea grape) thrive. This habitat has higher nutrients and is often sustained by decaying vegetation (much like a tropical rain forest). However the underlying soil is sand, and this ancient habitat (also known as a legacy beach) is a key sand storage site (like money in a vault). The whole system is beautifully interconnected. The back dune plants depend on the presence of grasses to hold the sand and take the brunt of the salt. In turn the grasses rely on the long term sand storage and stability of plants like Cocoloba.
Our analysis showed that for on a third to half of Gouverneur beach, most of the fordune and crest plants were dead or missing. The grasses had been lost. Consequently the dune sand had blown away. Instead a curving dune the beach profile had flattened. Plants adapted for life in the back dunes (e.g. Cocoloba) were now forced to the "foredune" and are were doing poorly, suffering from drought, salt, and low nutrients, and many were on the brink of dying.
SOLUTION
Finding the best methods
We decided on an experimental approach that was scientifically established and that would allow us to use the most natural and least invasive restoration techniques.
Many dune restoration projects carried out on dynamic beaches must bring in sand from outside, This can often change the distribution of grain size on the beach. Grain size determines the stability of beaches under a range of wind and wave conditions. We wanted to use existing sand if possible because that sand has "evolved" and stayed on the beach under the full range of conditions found at Gouverneur. Many dune restoration efforts also rely on bulldozers or other machinery to build artificial dunes. While valuable and often necessary, this equipment is unable to fully re-create the natural curve of the dune specific to the beach.
We evaluated the availability of sand and the dune conditions. We decided to manually move sand (using wheelbarrows) onto the dune where the wind quickly carved out a natural shape. We chose to focus our initial restoration efforts on the areas that were most badly degraded (approximately 35% of the beach area).
We decided on an experimental approach that was scientifically established and that would allow us to use the most natural and least invasive restoration techniques.
Many dune restoration projects carried out on dynamic beaches must bring in sand from outside, This can often change the distribution of grain size on the beach. Grain size determines the stability of beaches under a range of wind and wave conditions. We wanted to use existing sand if possible because that sand has "evolved" and stayed on the beach under the full range of conditions found at Gouverneur. Many dune restoration efforts also rely on bulldozers or other machinery to build artificial dunes. While valuable and often necessary, this equipment is unable to fully re-create the natural curve of the dune specific to the beach.
We evaluated the availability of sand and the dune conditions. We decided to manually move sand (using wheelbarrows) onto the dune where the wind quickly carved out a natural shape. We chose to focus our initial restoration efforts on the areas that were most badly degraded (approximately 35% of the beach area).
ECOSYSTEM BASED RESTORATION
An Ecosystem Approach
We then faced a decision on whether to plant early successional species (e.g. grasses) only and wait for sand to build up and new species to gradually establish. However, because the dunes were so degraded and because the beach is used by humans we opted for an ecosystem design approach. We decided to restore the full ecosystem include the foredune grasses, slope and crest shrubby species, and the backdune Cocoloba.
This entailed designing and building a horizontal layout to allow grasses to spread laterally, and also recreating the vertical architecture of the dunes where taller plants are interspersed with vines and grasses in order to maximize sand trapping and retention. There are challenges in a full ecosystem restoration as we have to pay attention to a variety of different nutrient requirements of plant species as well as difference in salt and drought tolerance.
We then faced a decision on whether to plant early successional species (e.g. grasses) only and wait for sand to build up and new species to gradually establish. However, because the dunes were so degraded and because the beach is used by humans we opted for an ecosystem design approach. We decided to restore the full ecosystem include the foredune grasses, slope and crest shrubby species, and the backdune Cocoloba.
This entailed designing and building a horizontal layout to allow grasses to spread laterally, and also recreating the vertical architecture of the dunes where taller plants are interspersed with vines and grasses in order to maximize sand trapping and retention. There are challenges in a full ecosystem restoration as we have to pay attention to a variety of different nutrient requirements of plant species as well as difference in salt and drought tolerance.
RESTORATION WORK
The Restoration
There were many months of research and searching for the right components before any "on the ground" work could start. The actual restoration work itself began in late October. By November the initial restoration experiment was completed.
4,500 grass plugs and 850 individual plants were used in the restoration.
Species used included
Grasses: Paspalum vaginatum (seashore paspalum); Panicum amarum (bitter panic grass)
Strand or slope plants: Suriana maritima (bay cedar); Jacquina (joewood); Argusia gnaphalodes (sea lavendar), Pithecellobium (blackbead catclaw): Ardisia escallonides (marlberry); Ernodes litoralis (golden creeper); Cocoloba (sea grape).
The diversity of plants was chosen to reflect the native diversity of dune vegetation and the conditions. For instance seashore paspalum is native to the Caribbean and North America. Highly salt tolerant it also requires lower amounts of nutrients that other beach dune grasses. Bitter panic grass responds to sand burial by growing upwards. The ability of panic grass to grow laterally and upwards while trapping sand, allows for the construction and stabilization of a continuous dune ridge, which is an important feature of sand dunes.
There were many months of research and searching for the right components before any "on the ground" work could start. The actual restoration work itself began in late October. By November the initial restoration experiment was completed.
4,500 grass plugs and 850 individual plants were used in the restoration.
Species used included
Grasses: Paspalum vaginatum (seashore paspalum); Panicum amarum (bitter panic grass)
Strand or slope plants: Suriana maritima (bay cedar); Jacquina (joewood); Argusia gnaphalodes (sea lavendar), Pithecellobium (blackbead catclaw): Ardisia escallonides (marlberry); Ernodes litoralis (golden creeper); Cocoloba (sea grape).
The diversity of plants was chosen to reflect the native diversity of dune vegetation and the conditions. For instance seashore paspalum is native to the Caribbean and North America. Highly salt tolerant it also requires lower amounts of nutrients that other beach dune grasses. Bitter panic grass responds to sand burial by growing upwards. The ability of panic grass to grow laterally and upwards while trapping sand, allows for the construction and stabilization of a continuous dune ridge, which is an important feature of sand dunes.
Before
|
After
|
Before
|
After
|
Q&A
What about building a sea wall?
On land people build walls to stop erosion. Walls on the beach do the opposite- they create erosion. Seawalls are a hard barrier that increase wave energy and lead to beach erosion. The natural beach slope reduces wave energy and keeps the sand on the beach (even if that sand moves out and back). A two-foot wave hitting a seawall has three times the energy and force of a hurricane winds.
What sand dunes do and do not provide
Beaches are naturally dynamic. Sand moves up and down or onshore and offshore on a daily, seasonal, or annual basis. Sand dunes will not stop the sand from moving. They will however ensure that sand is available to support and sustain the dynamic movement on the beach. Research has consistently shown that sand dunes have been vital in protecting lives and property in storms and tsunamis. But sand dunes do not offer total protection from everything including climate change. They do however ameliorate the damage and allow for faster recovery. By providing natural vegetation we can also sustain the animals including sea turtles that depend on this habitat for food and nesting sites.
Updates and Ongoing Progress
Please check back and visit the main page for updates, progress and more information on dune restoration.
If you want to know more please email us at [email protected]
On land people build walls to stop erosion. Walls on the beach do the opposite- they create erosion. Seawalls are a hard barrier that increase wave energy and lead to beach erosion. The natural beach slope reduces wave energy and keeps the sand on the beach (even if that sand moves out and back). A two-foot wave hitting a seawall has three times the energy and force of a hurricane winds.
What sand dunes do and do not provide
Beaches are naturally dynamic. Sand moves up and down or onshore and offshore on a daily, seasonal, or annual basis. Sand dunes will not stop the sand from moving. They will however ensure that sand is available to support and sustain the dynamic movement on the beach. Research has consistently shown that sand dunes have been vital in protecting lives and property in storms and tsunamis. But sand dunes do not offer total protection from everything including climate change. They do however ameliorate the damage and allow for faster recovery. By providing natural vegetation we can also sustain the animals including sea turtles that depend on this habitat for food and nesting sites.
Updates and Ongoing Progress
Please check back and visit the main page for updates, progress and more information on dune restoration.
If you want to know more please email us at [email protected]