North Carolina’s center of biodiversity
By Bruce A. Sorrie
In simplest terms, biodiversity is the total number of animals and plants that occur in a certain area, say, a country or state. When asked, most North Carolinians would say that here in the Tar Heel State, biodiversity is highest in the mountains, with the extreme range of elevation and rugged topography, including the Great Smoky Mountains National Park. A second area of biodiversity might be the outer Coastal Plain and barrier islands (including the Outer Banks), with its species-rich pine savannas, maritime-influenced plant communities, and huge numbers of nesting birds in summer and birds that winter there in the cold weather.
Yet, when the numbers are tallied, it is the lesser known and often overlooked Sandhills region that comes out on top. And not just in one category — plants, for example — but in several others as well. This seven-county region (Cumberland, Harnett, Hoke, Lee, Moore, Richmond and Scotland), while not very large — 3,384 square miles — encompasses a wealth of natural habitat types, which in turn support high overall biodiversity.
The Sandhills region overlaps three of the four major regions of the state, encompassing parts of the Piedmont and Coastal Plain as well as the entirety of the Sandhills. Each of those regions has different geology, soil types and topography, and the natural habitats reflect that.
In the Piedmont we see rocks when we walk through the woods, and rock ledges often front rivers such as the Deep and the Cape Fear. The Raven Rock State Park in Harnett County boasts one of the biggest ledges in the state. The brownwater (nutrient-rich) rivers of the Piedmont support wonderfully tall and shady forests on floodplains.
In the Coastal Plain we have Carolina bays, some forested with pond cypress, some open ponds, which support unique plants and animals that have adapted to fluctuating water levels. We also see xeric “bay rims” (dune-like sand ridges) bordering the bays, and dry-to-xeric flatwoods elsewhere.
In the Sandhills, we encounter myriad streamheads where rainwater collects to form acidic and nutrient-poor blackwater creeks and swamps. The margins of these streamheads provide habitat for many species typical of outer Coastal Plain savannas plus endemics found nowhere else. These streamheads are embedded within some of the highest quality longleaf pine communities in the entire Southeast: Fort Bragg, Camp Mackall, Sandhills Game Land, Weymouth Woods – Sandhills Nature Preserve, Carvers Creek State Park, Walthour-Moss Foundation, Calloway Forest Preserve, Eastwood Preserve and others.
Each section of the Sandhills has its own long and complex history, and each brings many products to the biodiversity table.
Now, for the numbers. These have been generated by the ongoing North Carolina Biodiversity Project (nc-biodiversity.com), an online resource where anyone can read species accounts, see images, and view maps of the flora and fauna of North Carolina.
Vascular plants (mosses, liverworts, lichens not included): Moore County is No. 1 in N.C. with 1625 species (including non-natives that have become established); Wake is a close second with 1622; and Orange a distant third with 1548. Notably, Richmond (1475), Harnett (1450), and Cumberland (1436) counties all rank in the top 10 for plant diversity.
Butterflies: Moore tops the list with 120 documented species; Richmond (115) and Cumberland (114) are in the top five.
Dragonflies and damselflies: Richmond is king of N.C. with 119; Moore is a close second with 117; Cumberland (115) is tied for third; and Harnett (110) is seventh.
Grasshoppers and crickets: Wake is far ahead with 110 species; Moore (84) is second; and Scotland (70) is fifth.
Freshwater fishes: Richmond and Brunswick counties are tied with 91; Moore (81), Harnett (76), and Cumberland (68) make the top 10.
Moths: Madison County in the mountains is No. 1 with a whopping 1352; Moore is 12th with 860.
Birds: Inland counties cannot hold a candle to coastal ones when it comes to numbers of species of breeding and migrant birds. Dare County boasts 434 species; Wake a very impressive 343 is fifth; but, at 253, Moore is only 23.
Mammals: The Sandhills region’s best is 38 species in Moore, far down the list, which is topped by Buncombe County with 66.
Of course, these lists are not static and will change over time as biologists and naturalists document new additions. However, the fact that several Sandhills counties rank in the top 10 statewide in multiple species groups will likely not change very much. It is remarkable that the seven-county Sandhills region, which represents only 6.3 percent of the area of North Carolina, supports half of the state’s vascular plants: 2,100 out of 4,200 species.
We who live here are lucky indeed to have such diversity at our doorstep. PS
Bruce A. Sorrie is a graduate of Cornell University and the author of dozens of scientific papers, including descriptions of 13 new species. He lives in Whispering Pines.