Essay: Demise of the Canebrake

Many accounts by the early naturalists and travelers that explored the South mentioned the existence of dense canebrakes found along coastal rivers and swamps. Some of these canebrakes covered hundreds, even thousands of acres, and extended for miles along river banks and channels. Indeed, these canebrakes were one of the most distinctive features of Southern riverine landscapes that extended well into the Piedmont, almost to the Foothills. Greenville’s Reedy River for example, gets its name from the abundant stands of giant cane, or river cane (Arundinaria gigantea), that were found growing there by early white settlers. In October, 1907, President Theodore Roosevelt spent two weeks hunting bears in a Louisiana bottomland forest that featured extensive stands of cane and from which he later wrote an article, “In the Louisiana Canebrakes.”

It is no accident that elk and bison that formerly occurred in the Southeast were often associated with canebrakes and cane meadows. This woody member of this grass family provided highly nutritious forage for a variety of browsing animals, a fact not lost on the pioneers who allowed their cattle access to cane stands under the free-range system. Settlers also realized that cane grew on some of the most fertile and productive agriculture soils. However, between overgrazing, clearing, dam construction, channelization, hydrology changes, both excessive burning as well as the exclusion of fire (cane apparently flourishes with some periodic burning that helps rejuvenate the stands and eliminate competing vegetation), and other factors, the extensive canebrakes of the South have all but disappeared, to the extent that they are now considered one of the most endangered plant communities in North America.

Switch cane is a common bottomland species at Congaree National Park.

When I was a youngster, the botanists considered our native cane, sometimes called bamboo, to be one species, even though earlier accounts classified them as two species: river or giant cane, and the smaller switch cane, A. tecta. But as what sometimes happens in taxonomic full circles, the experts have again split them back into two separate species, switch cane and giant cane. Recently a third species of cane, A. appalachiana, hill cane, found growing on hillsides in the southern Appalachians, has been described in the botanical literature.

Most native river cane is about an inch or inch and a half in diameter and fifteen to eighteen feet tall. It is the classic fishing pole cane of Americana and should not be confused with exotic and aggressive bamboo which may be four inches in diameter and thirty feet tall.

I have never seen a canebrake approaching anywhere near the sizes of those mentioned in the early literature. The ones I’ve run across in South Carolina have consisted of only scattered specimens, or small stands. I do remember years ago a stand of giant cane on the Francis Marion National Forest, and several stands in the Wateree and Upper Santee Swamps. The only giant cane of any extent I know of at Congaree is found on some narrow ridges at “Little Buckhead,” east of the Highway 601 causeway.

Cane was apparently much more prevalent at Congaree in the middle-1700s when the first land grants were made; it wasn’t uncommon for the surveyors to describe the land surrounding the grant as “all cane swamp.” That’s a tantalizing description since we don’t know exactly what “all cane swamp” meant – was it, for example, switch cane, or did it mean dense canebrakes of giant cane? It does fit the pattern noted by many, however, of cane being more abundant during historical times.

The largest canebrake I’m aware of in modern times occurred along the Ocmulgee River bottoms near Macon, Georgia, as noted by biologist Brooke Meanley in his book, Swamps, River Bottoms and Canebrakes. In the 1940s, he estimated one of these canebrakes covered a square mile (640 acres) with cane stems averaging fifteen to twenty feet high and maximum diameters of an inch and a quarter. This must have been an impressive sight to see. Meanley reported these stands were still extant in the 1970s; some of them later became part of the Bond Swamp National Wildlife Refuge, established in 1989.

Canebrakes are established primarily by vegetative means through the spread of underground rhizomes. Years may go by before the plants eventually produce flowers and seeds – after which they all die. The seeds are highly nutritious but lack much dormancy.

I was initially under the impression that the lack of canebrakes at Congaree was related to excess shading from a dense overstory. After Hurricane Hugo swept through in 1989, creating numerous holes and gaps in the canopy, I anticipated that some of these gaps would fill in with river cane. This did not happen, however, presumably because there was no available seed source, nor enough river cane to provide vegetative reproduction through rhizomes. This may explain why so many clearcuts found in today’s riverbottom forests fail to create canebrakes (and fill in with exotic privet instead).

What did respond after Hugo, albeit slowly, was switch cane, already in place and widespread at Congaree. This species seems to be quite different, ecologically, from river cane. It tolerates higher water tables and grows in low places and flats throughout the interior of the Congaree, and not just along the river front. It also appears to tolerate more shading than river cane. Over the past twenty-five years since Hugo I have noticed a significant amount of switch cane growing in places where it was sparse and uncommon before.

Something else going on with switch cane is that in places where the Congaree overstory suffered heavy hurricane damage, notably the park’s east end, the switch cane in places has gradually gotten taller, five to six feet rather than the usual three-and-a-half. The stems are still pencil-sized.

Negotiating a thicket of tall switch cane in the park’s East End.

Are the giant canebrakes of yesteryear an artifact of human origins? It is no coincidence that many of them were found on old, abandoned fields and clearings along the riverbank that had originally been created by Indians for their crops and gardens. The beginnings of intensive Indian agriculture in the Southeast, consisting of the three “sisters” – corn, beans and squash – dates back to around 1000 AD. Indian farming eventually led to the rise of permanent villages and towns and a corresponding increase in Indian numbers, estimated by some sources at 1.7 million at the time of first European contact in the Southeast. The rapid decline of Southeastern Indian populations after first contact, due primarily to infectious diseases but also to warfare and civil strife, resulted in thousands of acres of abandoned riverfront fields that eventually filled in with extensive canebrakes. Canebrakes were probably always part of bottomland hardwood native flora, but likely less extensive before Native Americans arrived on the scene and created ideal conditions for it to thrive and become established in American folklore.