Chapter 21

Merchant’s Millpond

A Cypress Swamp

APRIL C. SMITH

SCIENTIFIC FIELDS OF STUDY: Wetlands Ecology, Herpetology

In 1660, only seventy-five years after the first English settlers set foot in North Carolina, the area now known as Gates County was settled. This was a difficult region to explore because of the wet, muddy swamps and dense wooded forests. Most settlers would venture far south to avoid crossing this tough land, but a few chose to stay and make it home, recognizing they could harvest wood to sell for growing settlements. Most of the early rural communities that sprung up in Gates County survived by farming and selling lumber, and a few decades later, millponds were being established as regional marketplaces for families to sell produce and buy goods for survival. Millponds are bodies of water used as reservoirs to provide water energy to power mills. In 1811, Norfleet’s Millpond was built on Bennett’s Creek and became a bustling social center. A gristmill for grinding corn and a sawmill for cutting lumber also were established, along with a number of other supply stores, providing a center for commerce in Gates County.

For a little over a hundred years, Norfleet’s Millpond remained a busy marketplace, but in the late 1930s the millpond businesses all closed, and the surrounding land was sold to developers. In the 1960s, a nature lover by the name of A. B. Coleman of Moyock, North Carolina, purchased the land. He believed the land was too beautiful to develop and decided instead to donate 919 acres of the property, including the millpond, to the state. The name was changed eventually to Merchant’s Millpond to reflect the history of the site. In 1973 Merchant’s Millpond State Park was established on this land, and the Nature Conservancy donated another 925 acres of woodland to the park.

Today, Merchant’s Millpond State Park is known as one of the rarest ecological communities in North Carolina, where southern cypress swamp converges with hardwood forest and coastal pond. Bald cypress and water tupelo trees, some nearly 1,000 years old, are draped with Spanish moss, creating a scene out of storybooks. The number of online and print references calling Merchant’s Millpond a “magical place” highlights that it is certainly a place not to be missed.

What Makes a Swamp a Swamp?

In the most basic sense, a swamp is an area with low-lying ground where water pools for at least part of the year but soils remain waterlogged for most of the year. If this sounds to you like a wetland, you are correct. Other chapters in this book discuss various types of wetlands in North Carolina: bogs and fens in Chapter 3, pocosins in Chapter 23, and salt marshes in Chapters 26 and 27. What is it about a cypress swamp that is so different from these other types of wetlands? The trees.

Most trees’ roots cannot withstand waterlogged soils, never mind full-water immersion. Trees need oxygen, and since water contains less oxygen than air, trees that grow in the water must adapt to growing in low-oxygen environments. Bald cypresses (Taxodium distichum) and water tupelos (Nyssa aquatica) have adapted to such conditions and thrive here. They only require a dry period long enough for their seeds to germinate before flooding. Both types of trees have a wide swollen base and special root systems that provide a firm hold in soggy soils.

Bald cypress trees give Merchant’s Millpond its unique character. They are the trees that are most recognized in this type of landscape, but cypress trees are best known for the “knees” that grow nearby. They, of course, are not actually knees at all, but a special kind of root called a pneumatophore, which means “air bearing.” It is thought that the pneumatophores probably are responsible for taking air from above the water line down to the trees’ horizontal roots located under waterlogged soils. It would be a safe bet to assume that cypress knees also provide a little extra support for the trees from which they sprout. In this case, perhaps the term “knees” fits after all. Bald cypress trees are deciduous conifers, which is unusual. Conifers are cone-bearing trees with needles, such as pine trees. Conifers usually stay green all year long, losing only part of their needles. But the bald cypress is deciduous, which means it actually loses all of its needles every year, giving it a “bald” appearance in the winter.

Tupelos are also adapted to growing in standing water, but they are not as well known as the bald cypress. Tupelos exist as separate male and female trees, a reproductive method known as dioecious reproduction, which we discussed in Chapter 14, “Prairie Ridge Ecostation.” The females have small, green, pollen-producing flowers that are pollinated by bees before becoming a pulpy purplish-red fruit much loved by swamp wildlife, although a little bitter for people. The juice from the tupelo fruit is very sour and can be used as a substitute for lime juice. In some places in the southeastern United States, bee boxes are brought into the swamp and placed on platforms next to tupelo trees to make a special type of rare honey called tupelo honey.

Merchant’s Millpond State Park has a terrific Kids in Parks TRACK Trails Program where you can learn more about these trees and others in the park as you hike through the forest. Your tree search should include red maple (Acer rubrum), tulip tree (or yellow poplar) (Liriodendron tulipifera), American holly (Ilex opaca), sassafras (Sassafras albidum), and American beech (Fagus grandifolia). Each of these trees has a special function in the forest, and many have interesting stories as well. For example, in North Carolina, nectar from tulip trees is an important source for another unique and delicious type of honey, while sassafras was once used to flavor candy and root beer.

Figure 21-1. A bald cypress tree growing in Merchant’s Millpond. Photo by Jane Wyche, NC State Parks.

Figure 21-2. An up-close view of the bald cypress tree’s trunk as it grows in the water. Photo by Jane Wyche, NC State Parks.

Figure 21-3. If you look at the bottom of a cypress trunk you will see its “knees” sticking out of the water. Photo by Stephen Smith.

Who Else Lives Here?

If you are looking to immerse yourself in a herpetology paradise, this is the place for you. Herpetology is the study of reptiles and amphibians. Of all the reptiles and amphibians that live in and around Merchant’s Millpond, most visitors tend to come looking for the alligators. Merchant’s Millpond State Park is the northernmost boundary for the American alligator (Alligator mississippiensis). A small cluster resides within the boundary of the state park, but until recently most people thought that alligators were not able to survive this far north. About twenty-five years ago a fisherman caught a baby alligator within the state park boundary, and state officials have been watching this cluster of ancient reptiles ever since. Because the weather can get cooler here than in more southerly parts of North Carolina, alligators have a shorter growing season and reproduce much less frequently. As a result, the cluster that lives here will not expand rapidly but appears to have a stable population.

Figure 21-4. Water tupelo trees in the swamp. Photo by Jane Wyche, NC State Parks.

Figure 21-5. American alligator (Alligator mississippiensis) close-up. Photo by Mike Dunn.

Now I bet you’re thinking, why does the weather restrict an alligator’s ability to live farther north of Merchant’s Millpond? Let’s talk a little about alligator biology. American alligators exhibit a fascinating trait, where the sex of the eggs in a nest is determined not by genetics, as in mammals, but by the temperature of the surrounding environment during incubation. So, if Mama alligator lays approximately fifty eggs, and the temperature in the nest is lower than ~86°F (30°C), all of the babies will be female. If the temperature of the incubating eggs is higher than ~93°F (34°C), all of the babies will be male. Usually in a nest, the incubating temperature varies, and the hatching baby alligators will be both male and female; but in northern North Carolina, the temperatures are more consistently cool, thus affecting the eggs. The closer we get to the Virginia border, temperatures during the early part of the sixty-five-day incubation period in May–June hover precariously around that 86°F (30°C) boundary. Some years the temperatures do not rise above the magical 80°F (27°C) survival mark for either gender, which means none of the eggs will develop at all. But between 80°F (27°C) and 86°F (30°C), all the offspring are females, limiting the alligators’ future reproductive potential in the region because there are no males for mating. It is for this reason that the alligator cluster living at Merchant’s Millpond is so very special. Here is something for you to ponder: what happens when climate change increases the late spring temperatures along the mid-Atlantic coastline? These impacts are already happening. Some types of animals are already expanding their habitat ranges due to changing temperatures. It is possible that, in your lifetime, we will see alligators in Virginia after all.

The alligator population, small as it might be, is really good for the aquatic environment at Merchant’s Millpond. Because alligators are apex predators, meaning they are at the top of the food chain, they help maintain healthy populations by preying on other animals in the swamp, including amphibians, snakes, turtles, birds, fish, and any mammal that does not move fast enough. The baby alligators, called hatchlings, will often feed on snails, spiders, and worms. The role than an organism fills in a natural environment is called its niche, and apex predator is a very important niche. When the population of an apex predator declines, the populations of its food sources begin to grow uncontrollably unless another predator moves into its place. In the case of a cypress swamp, secondary predators capable of filling this coveted ecological niche might include foxes, large birds of prey, or even large snakes. Eventually, if no suitable predator can fill the niche, overgrown populations of organisms will not have enough food to eat, and the food web can collapse.

Figure 21-6. Pinewoods tree frog (Hyla femoralis). Photo by Jane Wyche, NC State Parks.

Alligator movements throughout the water column also serve to stir the water, keeping it oxygenated and preventing eutrophication. This is a term used to indicate an excess of nutrients in the water, such as nitrogen and phosphorus, from fertilizers. Phosphorus is a common ingredient in many detergents as well, so it is easy for it to make its way into aquatic ecosystems when it is washed down drains and sewers. When extra nutrients enter an aquatic system, the immediate result is rapid plant and algae growth, just as if you were to add fertilizers to your garden at home. But excessive growth will cause plants to compete for space and light, eventually leading to die-offs. Plant and algae die-offs result in oxygen depletion in the water, which then causes the aquatic animal life to die. Eutrophication is a type of water pollution that can be mediated by smart consumer choices like purchasing detergents less harmful to the environment. In this particular circumstance, the alligators’ movements help support the health of the aquatic system.

And Other Than the Gators …

In the winter, Merchant’s Millpond is a bit quieter than in spring and summer. When it’s cold outside, cold-blooded amphibians, like frogs and salamanders, spend the season in a slow, relaxing state of hibernation. Aquatic species will sit mostly motionless on the pond bottom, while terrestrial species generally will bury themselves to hibernate on land. Frogs and toads have special “antifreeze” that keeps their bodies from freezing during winter. High concentrations of glucose, or sugar, in their vital organs, like the heart and lungs, protect them from freezing. Other parts of the body may freeze, and the heart and lungs may stop working; but when the temperature rises, the body will thaw, and the heart and lungs will start working again. When the weather warms, frogs emerge from their long rest, and after spring and summer rains, they make their presence known to mates with a loud frog chorus that you definitely will want to experience. Merchant’s Millpond is home to approximately 22 species of frogs and toads, as well as 12 species of salamanders. Contact the Merchant’s Millpond visitor’s center below to ask for the best times and locations to visit.

Figure 21-7. Black rat snake (Pantherophis obsoletus) on a cypress trunk. Photo by Jane Wyche, NC State Parks.

Other animals that you might see in Merchant’s Millpond include 11 turtle species, with the 2 most common being yellow-bellied sliders and box turtles. If you are interested in participating in the box turtle survey, please see a ranger for more information. Two species of primitive fish, the bowfin and the longnose gar, can often be seen from a canoe on the water. These fish have remained unchanged for millions of years and can grow to be very large. Some reports indicate that the bowfin can grow to approximately 2.0 feet (0.6 meter), while the longnose gar can grow to be over 6.0 feet (1.8 meters). Snakes are also abundant here—22 different species to be exact. Sightings of cottonmouth, water snakes, kingsnakes, timber rattlesnakes, and copperheads indicate a healthy terrestrial ecosystem in the park.

Before You Go

There are many fascinating things to see at Merchant’s Millpond. It is truly a relic of the past and harbors numerous living organisms as evidence. Lassiter Swamp sits at the far north end of Merchant’s Millpond. It has an ancient landscape displaying the cypress and tupelo trees in all their glory and begging to be explored by canoe. There are incredible scenic hiking trails here, ranging from a 0.3-mile (0.5-kilometer) trail that is handicap accessible and great for young kids, to the popular 6.0-mile (9.7-kilometer) Lassiter Trail. But without a doubt, the best way to see the area is by canoe. It takes about two hours to paddle across. Bring your own or rent one at the park for the day. Camping is also available at Merchant’s Millpond State Park. Call ahead for reservations. Consider attending a ranger talk while you’re visiting. There are numerous programs to provide you with more information about herpetology, plant life, and the history of Merchant’s Millpond.

References and Resources

“Bald Cypress: Taxodium distichum.” National Wildlife Federation, https://www.nwf.org/Educational-Resources/Wildlife-Guide/Plants-and-Fungi/Bald-Cypress. Accessed November 7, 2018.

Emmer, Rick. “How Do Frogs Survive the Winter? Why Don’t They Freeze to Death?” Scientific American, November 24, 1997, https://www.scientificamerican.com/article/how-do-frogs-survive-wint/. Accessed November 7, 2018.

Ferguson, Mark W. J., and Ted Joanen. “Temperature of Egg Incubation Determines Sex in Alligator mississippiensis.” Nature 296 (April 29, 1982): 850–53, https://doi.org/10.1038/296850a0. Accessed November 7, 2018.

“The History of Gates County.” GatesCounty.gov, https://gatescounty.govoffice2.com/index.asp?Type=B_BASIC&SEC=%7B9FA438DA-A6A9-48BA-B015-DBA6C392FF0D. Accessed November 7, 2018.

Lewis, J. D. “A History of Gates County.” Carolana.com, http://www.carolana.com/NC/Counties/gates_county_nc.html. Accessed November 7, 2018.

“Merchant’s Millpond State Park.” Kids in Parks, https://www.kidsinparks.com/merchants-millpond-state-park. Accessed November 7, 2018.

Powell, William S., ed. Encyclopedia of North Carolina. Chapel Hill: University of North Carolina Press, 2006.

“Tupelo Honey.” Honey Traveler, http://www.honeytraveler.com/single-flower-honey/tupelo-honey/. Accessed November 7, 2018.

Website: https://www.ncparks.gov/merchants-millpond-state-park

Contact: phone: (252) 357-1191; email: merchants.millpond@ncparks.gov

Address: 176 Millpond Road, Gatesville, N.C. 27938

GPS Coordinates: N 36°26.22, W 76°41.94