Nature’s notebook

Congaree: A mysterious forest of champions

The river banks show evidence of disturbance by feral hogs. Photo: Ruth Ann Grissom

The Uwharries have produced state champion longleaf and shortleaf pines, but the vast majority of loblollies in the region are harvested long before they reach maturity. I tend to think of them as a long-rotation crop. A recent visit to Congaree National Park near Columbia reminded me of the loblolly’s glorious potential.

At more than 26,000 acres, the park encompasses the nation’s largest contiguous tract of Southern, old-growth bottomland forest. The canopy is among the tallest broadleaf forests in the world. Before Hurricane Hugo in 1989, the park boasted 14 state and seven national champion trees. Record species include understory trees such as pawpaw and American holly in addition to the loblolly and other canopy trees such as sweetgum and cherrybark oak.

A big loblolly pine as seen from elevated boardwalk. Photo: Ruth Ann Grissom

The Congaree and Wateree Rivers flood the park several times a year, depositing silt and clay from their headwaters in the Piedmont. (The Catawba River flows into the Wateree, carrying much of Charlotte’s stormwater runoff and debris, as well as treated wastewater.) Some areas remain inundated. The fertile soil and temperate climate create ideal growing conditions for many trees. Historically, longleaf have dominated the uplands in this area of the inner coastal plain, while loblollies have had an advantage in the bottomlands because they are more tolerant of wet conditions. In fact, in some Southern dialects, the word loblolly can refer to a mudhole or mire.

While Congaree’s trail network offers longer hikes, it’s possible to get a sense of the park’s majestic forests over the course of the 2.4-mile Boardwalk Loop Trail. Heading west from the visitor center, the trail soon passes through a swamp with impressive stands of tupelo and bald cypress. Some of the latter are estimated to be at least 1,000 years old. In the late winter canopy there’s often a woodpecker drumming or a barred owl calling even in broad daylight. These cavity nesters thrive in old-growth forests that harbor dead and dying trees.  In the spring they’re joined by legions of prothonotary warblers. The birds, also known as swamp canaries, are the only Eastern warbler that nests in cavities.     

Even on higher, drier ground, water puddles in shallow depressions left by windblown trees. Their heavy crowns make them vulnerable to heaving when the soil is soggy. Massive root systems stand perpendicular to the earth, creating mixed-media works of art. The loss is also a gain. A single downed tree might create a half-acre canopy gap where sunlight reaches the forest floor, allowing a diverse suite of species to flourish. The decaying wood further enriches habitat and soil.

The eastern section of the boardwalk is elevated, providing views of spectacular loblolly pines. Many are roughly 250 years old, and a few reach nearly 170 feet. They tower over the hardwood forest. A shiver runs up the spine. The observant and inquisitive will be moved to wonder: how? How did this forest come to be? Could this be typical forest succession, played out over centuries? Could a pioneer species like loblolly pine out-compete climax hardwoods in a virgin forest? Are they the result of natural disturbances? A devastating hurricane or series of tornados? A lightning strike or cataclysmic fire?

To help me answer those questions, David Shelley, education coordinator at the park, was kind enough to speak with me at length and share scientific papers about research conducted at Congaree. Neil Pederson and Robert Jones speculate that in pre-settlement times, loblollies would have occurred as single trees or small clusters scattered through the forest, not the even-aged stands we associate with a pioneer species. They believe human disturbance likely played a significant role in shaping the forest we see today. 

People have long been drawn to this forest. Hunter-gatherers have passed through it for more than 10,000 years in search of abundant game. So did recent sportsmen. By the time Spanish explorer Hernando De Soto arrived in 1541, Congaree and Catawba tribes were growing corn. The forest sheltered people like Frances Marion, the Swamp Fox, who likely hid here after a nearby skirmish during the Revolutionary War. Fugitive slaves sought refuge here as well. Later, moonshiners built clandestine stills.

While the area within the park boundary was largely spared wholesale conversion to agricultural plantations or industrial timber production – though slaves probably built the small dikes and cattle mounds still seen in ruin today – evidence suggests an impact from subsistence farming and logging. A practice known as “girdling” was common in this area. Instead of felling trees and removing stumps, a tree was killed and left standing, an efficient way to create sunny spots for food or grazing plots. The tree would eventually fall, just as if it had died of natural causes. 

The loblollies along the elevated boardwalk aren’t regenerating under the hardwood canopy, and seedlings that do establish themselves in areas of natural disturbance aren’t doing so at a rate that would result in the forest we see today. If the current density is owed to human intervention, it’s humbling to realize today’s impacts will also shape the forest three centuries from now. We’ve only recently reckoned with a century of fire suppression, and we don’t yet have good data on the role of invasive species like feral hogs and privet. The most profound effect might be climate change, which could alter cycles of flood and drought. Elevated carbon dioxide levels have been shown to promote the growth of poison ivy, which could also affect forest dynamics. 

Congaree is a forest where mysteries and possibilities easily lodge. On a misty afternoon as dusk approaches, you want to believe the pileated woodpecker that swoops across the path could be a surviving ivory bill. The forest is so different from the poor scraps of second- and third-growth hardwoods we’re accustomed to seeing in the Piedmont, it seems primeval. It gives us a glimpse of time and forces greater than ourselves. But Congaree’s majestic loblolly pines stand testament to the impact humans have had on the land. If their seedlings survive to a comparable age, what stories will the forest then tell about our current stewardship?