Recently, we identified keystone plants of Ecoregion 5, the Northern Forests, which mingles with the upper part of the Eastern Temperate Forest, or Ecoregion 8. In the North, Ecoregion 8 runs from the Middle Atlantic states and southern New England west through the Ohio Valley to Wisconsin—roughly from the 40th to the 45th parallels.
But that’s only half of the Eastern Temperate Forest region. The other half exists south of the 40th parallel, from Delaware west to Missouri, from Florida west to Louisiana, and all the land in between. In other words: the South, as distinct culturally as it is ecologically. That’s our focus in this article.
Keystone plants support vital wildlife
This region’s keystone plants include the trees, shrubs and flowering perennials that attract the most butterflies and moths whose larvae are caterpillars. These caterpillars are crucial food for the newly hatched chicks of spring. We’ll also identify native plants that host pollen specialist bees. These bees rely on the pollen of these plants for their health—and consequently, they're part of the health of the whole ecosystem.
This series would not have been possible without the work done by Dr. Doug Tallamy at the University of Delaware in identifying keystone plants and by Jarrod Fowler, who has identified the host plants of pollen specialist bees. We can all be grateful for their important work.
Ecological zones are diverse
While the entire Southeastern United States is classified by the National Wildlife Federation as Eastern Temperate Forest Ecoregion 8, when looked at in granular detail, it has many very different ecological zones. The Atlantic coast of North Carolina isn’t at all like the limestone plateau of central Kentucky or the hills and valleys of the Appalachian Mountains from Virginia to Georgia. In fact, the Environmental Protection Agency identifies 17 different ecological regions in the Southeastern United States.
While these 17 regions differ, they also share similarities. Wherever keystone plants grow across the South, they enhance and strengthen their ecosystems’ interlocking web of life. Where they grow, their region’s natural health is supported.
Related article: Ecoregion 5 and Its Keystone Plants
Keystone trees in Ecoregion 8
Across the entirety of the Eastern Temperate Forest, oaks remain the champion keystone trees because they host the greatest number of insects whose larvae are caterpillars. Oaks suited for the South include white oak (Quercus alba), southern red oak (Q. falcata), live oak (Q. virginiana), willow oak (Q. phellos) and shumard oak (Q. shumardii). All are attractive to hundreds of species of moths and butterflies whose caterpillars kick-start the food chain for the whole ecosystem.
Trees in the genus Prunus not only host almost as many species of caterpillar insects as oaks, but their prolific fruit also helps birds and mammals survive. Southern states’ keystone natives in this genus include the American plum (Prunus americana), black cherry (P. serotina) and chokecherry (P. virginiana). Of course, there are other Prunus trees that aren’t natives but function like them in their ability to support caterpillars—and to feed the thieving wildlife that comes to steal your fruit. Home orchardists will know what I mean!
The hilltop woodlands around one of my previous homes in the Appalachians were filled with black birch, and in the early years of the 20th century, local farmers would harvest young black birch saplings to be boiled in the birch oil distilleries that dotted the mountainsides. This oil was used to make birch beer—a sweet soda pop similar to root beer. I didn’t know it at the time, but black birch (Betula nigra) was a mighty keystone plant that hosted 284 species of caterpillar insects and was a reason why our spring mornings were often a symphony of birds celebrating the dawn before flying out to forage caterpillars to feed their newborn chicks.
Related Article: When Planting for Pollinators, Don't Forget Trees
Keystone trees support birds and pollinators
The southland is native territory for 50 species of birds, all of which flourish in habitats enhanced by keystone species of plants. And this doesn’t include the skyful of birds that pass through on their annual migrations up and down eastern North America.
Other keystone trees native to the South include the Eastern cottonwood (Populus deltoides), southern crabapple (Malus angustifolia), pitch pine (Pinus rigida), Virginia pine (Pinus virginiana) and the beloved hickory species: pignut hickory (Carya glabra), shagbark hickory (C. ovata) and the mockernut hickory (C. tomentosa). The latter is a nursery for over 200 species of moths and butterflies, but it’s also prized for its nutmeats, much sought after by wild mammals and people with a taste for exquisite quality (and time on their hands, because the hard shells don’t yield their nutmeats easily. I personally have spent two hours breaking the thick shells and picking out the incomparably tasty nutmeats from their twisting channels, only to have a small cupful of nut pieces to show for my effort).
Besides their contribution to the region’s health, hickory wood creates savory, perfumed smoke when smoldering in farmers’ smokehouses hung with bacon and hams. Its wood is unbreakable. Two hickory walking sticks cut by my dad in 1949 and passed on to me when he died are standing in the corner of the office where I’m writing this 76 years later, and they’re just as tough as when he whittled them.
Related Article: Plant This Wildlife-Friendly Three-Season Tree
Keystone perennials in Ecoregion 8
A major sign of ecological health is robust pollination of native plants, ensuring a good yearly supply of seeds and fruits to continue healthy populations. A group of keystone perennials in the South that attract and support pollinators to them include black-eyed Susan (Rudbeckia hirta), swamp milkweed (Asclepias incarnata), foxgloves (Penstemon digitalis), smooth blue asters (Symphyotrichum laeve), eastern columbines (Aquilegia canadensis) and purple coneflowers (Echinacea purpurea).
This group provides essential sustenance and habitat for birds, butterflies, bees and other pollinators. They make a beautiful association of flowers from spring to fall and will return year after year with minimal upkeep. Their pollinators go on to serve many other plants that fill niches in the local ecosystem.
Related Article: Best Plants for Pollinators, by Region
Keystone plants are foundations of Southern wildlife food chains
Making sure there are keystone plants in your garden and landscape enriches the food chain from the plants to birds to small mammals like voles and mice; to squirrels, possums, raccoons, deer; and into the ranks of predators like bobcats, coyotes, raptors and even rare mountain lions that have been spotted in Florida.
But there are lesser-known animals that also benefit from the presence of keystone plants. For instance, the Cumberland dusky salamander, found mostly in Tennessee, feeds on small invertebrates found on the leaves of keystone plants that litter the forest floors, and the salamanders themselves may be food for small mammals, snakes and certain birds.
Crawfish rely on freshwater habitat
There is also a denizen of southern freshwater creeks and waterways whose clean habitat depends on keystone plants in a strong ecology: the crayfish, or as it’s sometimes called, the crawdad. Besides providing food for wild animals, this little crustacean that looks like a miniature lobster feeds the food chain right up to and including Homo sapiens. It’s such an entwined part of the local ecology in the South that its shell is often home to another, smaller crustacean that is its symbiont.
Down in New Orleans, there’s no dearth of Cajun restaurants happy to serve you plates of boiled crawfish—or even better, crawfish etouffee. Those symbionts are so small you won’t even know they’re there.
To learn more about keystone plants for your region, see the National Wildlife Federation’s gardenforwildlife.com. The ecosystem, from crickets to frogs to birds in the trees and hawks in the sky, will sing your praises. Loudly.
Image credits (top to bottom):
Brown thrasher on chokecherry Biodiversity Heritage Library/Public Domain/Flickr.com
Shumard oak Dan Keck/Public Domain/Flickr.com
Penstemon Mike Kestrel/CC BY 2.0/Flickr.com
