Costal Hummocks – Part 2, Plants at Work

Nature Prevails in these two fashions. Some deeply rooted plants at some distance from the water line survive and hold the soil forming hummocks with their roots. This is a continuation of the previous post describing the effects of the hurricane Ian. The hummocks also contain the roots of herbaceous plants which are rapid growers that tolerate the sea water conditions. Together this army of plants are hard at work here: plants begin to trap and fix into place wind born sand.

The feature image simultaneously captures three concepts. The red severe weather warning flags are fully horizontal showing that there is a persistent 25 to 35 mph wind; the water and dunes are closed to the public; the pure white sand is flat and extends deep into the inland beyond any berm area. These are all signs that this is a distressed area that is a long way from a return to its former condition. The contributing factors are water and wing storm damage, persistent wind blowing onshore reducing the ability to hold sand; no plant roots have developed to stabilize the beach. Public access to the dune area would compromise the fragile environment and endanger its future.

This chart shows the Delver-Wiggins Pass State park. The red line is the only available walking path. The remaining park area is closed to the public at this time. There has been so much damage that the park service wants the public areas to recover without an interfering visitors who may simply walk on the new plants and retard regrowth.

The yellow lines describe the areas of interest which I was able to photograph using a long focal length lens. It was a very windy day with very few people on the beach.

Surviving old growth trees on islands of high ground hold the soil and provide the plants an opportunity to enter into the battle against the sea.

Sea Grapes and Railroad vines start at the hummocks

Sea grapes (Coccoloba uvifera) (no flowers, no fruit).

Railroad vines ((*Ipomoea pes-caprae*) (no flowers).

Important second defense plants, grasses are difficult to identify from a distance, perhaps saw grass, sea oats and a reed.

Long leaf yellowtop, (*Flaveria linearis*).

Yellow joy weed (*Alternanthera flavescens*)

The mangroves in the wetlands do not appear to be as resilient as the plants on the berms. They are suffering from the high salinity which is still retained in the water of the swamps. These areas need more rain and better drainage to dilute the salt and flush the system.

Mangroves in the swamp behind the tropical hummock.

Discussion about the future:

For the last 50 years this parkland has been tended and enjoyed by many people. It has been subjected to two cat-4/cat-5 hurricanes. Expensive rehabilitation was constantly used to reconstruct the beach berms, hummocks and swamps. Perhaps preventive measures would be a better alternative to this practice. Simple measures such as avoidance of cleaning beaches of detritus on beaches which trap sand and add nutrients for plant growth. There are more aggressive approaches. As seen in the illustration below***, these methods could include sand fences, sand entrapping peers and more demanding but effective projects such as offshore islands, and breakwaters, reinforced dunes, rip rap walls, mangroves, and fewer public use beaches. These may not be popular however they will hold the sand and protect the hardwood hummocks and the mangrove forest. This will not stop rising ocean water however, it will provide improved mitigation from the saltwater surge damage to private and commercial property and the lives of the tens of thousands of people who live, work and recreate here.

There are hundreds of references on the topic of beach dune restoration but fewer references discussing beach erosion preventive measures. Depending on wind and water beaches come and go. Because of our interference in natural cycles we may be a little late to consider let nature take its course.