Wherever we find ourselves, we may be in situations where we need to adapt. From an unexpected confrontation to a new job, some situations may show us new parts of ourselves. Plants that live on dunes in our beautiful parks are no exception.
Dunes often are viewed as endless mounds of sand devoid of any life, but this is far from the truth. Although anything that lives there needs to be able to handle difficult conditions, the plants in dune ecosystems are unique and beautiful! Plants in these environments need to find a way to deal with harsh sunlight, a constant onslaught of sand particles, high temperatures, low fertility, little water availability, and high levels of salt.
Since winds are high in these areas, the first thing a plant in this unwelcoming habitat needs is a strong support system. Wide, branching out roots provide little support and leave them susceptible to getting blown away. Dune plants will often have long, deep roots called tap roots that secure them in place. These tap roots can also “tap” into deeper water sources to help combat the low water availability in the soil.
To deal with the intense sun, some plants’ leaves, like the Verbena species, will move with the sun and stay vertical to avoid exposing themselves too much. Verbenas also can be covered in sticky hairs that intentionally get sand stuck to them. This provides a natural cover against the sun and salt spray.
Plants like the adorable Camissoniopsis cheiranthifolia (try saying that five times fast!) have tiny pale blue hairs that protect them from the sun and retain moisture. Also known as the beach primrose, you can spot them in the spring by their lovely pale yellow flowers.
Verbenas and beach primrose plants are usually found on pioneer dunes or foredunes, meaning they need to be able to adapt to the harshest conditions. We often view dunes as monolithic, but different parts of the dunes have different levels of harshness. The front of the dune closest to the ocean is known as a pioneer dune, which is where it is most difficult to survive. These are the dunes that are also easily damaged by human activity.
The creation of dunes is very delicate and requires plants. As sand is blown inland by ocean winds, the particles will hit the plants and slowly form a hummock. A hummock is a mound of sand that is the early beginnings of a dune. Eventually, the plant gets buried altogether and a dune is formed.
In a process known as dune succession, more and more plants fill the dune’s surface, and the dune can become completely stabilized. These communities still need to be able to live with low fertility soil, but no longer need to worry about intense sun and an onslaught of sand particles. Since these plants are less likely to be buried by sand, this creates a coastal dune scrub environment, which is more hospitable to a variety of plants like larger shrubs and less hardy plants. Some can even have trees, like the Los Osos Elfin Forest and its adorable pygmy oak trees! These trees have slanted, sometimes horizontal branches that are shaped by the direction of the wind that was blowing when it was growing.
Human activities and natural processes like storms can create features called blowouts in dunes. Blowouts begin as gaps in vegetation, but quickly become a wind tunnel that can destroy the dune. 23% of California’s coast is sandy beaches, but only 1% are dunes. This is why dunes are so important to protect and maintain their native vegetation to keep them strong.