Wind and sun
Wind and water
There is little or no decaying plant and animal material to enrich the dunes.
There is too much Oxygen.
There is too much Hydrogen and Oxygen.
The organisms in a dune habitat consume more Nitrogen than they produce.
Water (Hydrogen + Oxygen)
Ocean breezes provide a steady flow of wind.
Dune plants provide Oxygen to the dune.
Ocean spray provides Oxygen in the water that mists the dunes.
All of these.
Ghost crabs feed on decaying plant and animal remains that accumulate at the side lines.
Ghost crabs feed on insects and small crabs found on the ocean beach.
Ghost crabs feed on mole crabs and coquinas found at the shoreline.
Ghost crabs feed on dune plants and detritus found on the ocean beach.
Waves deposit the fine sand onto the dune.
Saltation carries only the finest of beach sand.
Saltation mixes salt with sand making it more finer.
Fine sand is more porous.
The higher the dune, the larger the vegetation behind it.
The higher the dune, the smaller the vegetation behind it.
The dune height does not affect the vegetation behind it.
The lower the dune, the larger the vegetation behind it.
Beach sand cannot hold nutrients or water because the sand is loose sediment made up of broken-down rock and shell particles that water and nutrients can easily run through.
Beach sand cannot hold nutrients or water because the sand is made up of clay and mud that water and nutrients can easily run through.
Beach sand can hold nutrients if clay and detritus are added to the soil.
Nutrient minerals leach out (filter out) of sand quickly because of the wind and waves on the beach.
Because sand is a light and bright color, it reflects sunlight and has a higher albedo in comparison to the ocean, which appears blue, is a darker color, and which would absorb rather than reflect sunlight.
Because sand is bright, it absorbs sunlight. It has a lower albedo in comparison to the ocean, which appears blue, and which reflects rather than absorbs sunlight.
The beach sand and the ocean have equal albedo’s during the summer when the sunlight is more intense. They both reflect sunlight.
Because the ocean is a darker blue in winter than summer, the ocean can reflect more light in summer than winter.
Back dune soil retains moisture because the vegetation provides a canopy of shrubs and trees, lower soil surface temperatures, and reduced evaporation.
Back dune soil retains moisture because rain and high wave water over washes the dunes forming ponds that keep the back dunes moist.
Back dune soil is moist because of wind and salt spray.
The frontal dunes dry out due to wind and salt spray.
These plants have flexible, long, narrow leaves that curl inward and blades that turn to a vertical position that can withstand whipping winds.
These are plants that grow in the summer and die at the end of the summer season because they need continuous access to sunlight and heat.
American beach grass and sea oats tend to have short and woody structures capable of capturing and holding sand in place.
American beach grass and sea oats plant fibers are light in color, reducing the amount of heat it can absorb.
Dune animals move back and forth between the dunes and the maritime forest to get fresh water from ponds in the maritime forest and move to the dunes to scavenge and forage for food at night.
Dune animals move back and forth between the dunes and the maritime forest because of the dune heat, wind, and salt spray.
Dune animals move back and forth between the dunes and the maritime forest because they eat ghost crabs.
Dune animals move back and forth between the dunes and the maritime forest to avoid predators.
This diagram shows a low frontal dune. Low frontal dunes do not protect dunes behind them. The ocean side of the back dunes is exposed to the full force of the ocean winds, salt spray, and whipping sands.
This diagram shows a medium frontal dune. A medium-sized frontal dune protects the sand shadow side of the dune behind it. During storms, the ocean side of the back dunes is vulnerable to the forces of the ocean.
This diagram shows a high frontal dune. A high frontal dune protects the back dune behind it. High frontal dunes reduce the effects of whipping sand and salt spray, protecting the growth of vegetation behind it.
This diagram shows a storm eroded lower frontal dune. The back dune is higher because the storm winds moved sand to build the back dune and expose its dune plants.
How much salt is in the water
The movement of sand along the shoreline
The effect of salt spray on barrier island plants
Saltation is the movement of sand by 10 mph or greater winds that create a dune.