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Sugar Hill: A Microcosm of Central Appalachian Ecology

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Cove Hardwood Forest: Remnant of the Arcto-Tertiary Forest

Sixty million years ago, dinosaurs had recently disappeared from the earth and mammals were just starting to take their place. The vast Arcto-Tertiary forest coated the northern latitudes of North America, Europe, and Asia with broadleaf deciduous trees much like the ones you see around you today. Beech, chestnut, elm, alder, birch, hornbeam, aspen, walnut, hazel, sweetgum, sequoia, and ginkgo shared the canopy.

Just like in our current Appalachian forests, the trees of the Arcto-Tertiary forest turned brilliant shades of yellow, orange, and red before dropping their leaves in the winter. And in early spring before the leaves returned, herbaceous perennials on the forest floor burst into bloom, only to fade away as the trees regained their leaves.

This rich forest depended on a warm, humid climate and before long its range began to contract. Two or three million years ago, the glaciers of the first ice age drove the plants of the Arcto-Tertiary forest south. The glaciers melted then re-formed time after time. In Europe, the Arcto-Tertiary forest was battered up against the east-to-west aligned Alps until most plants perished. Much of North America and Asia had turned into grasslands as the climate dried, so on these continents the forest became restricted to a couple of mountain ranges --- those in eastern North America and those in eastern China.

In these two refuges, the forest survived by migrating north and south as the climate warmed and cooled. The mountains provided protected nooks and crannies --- high elevation ridges where cool-loving species could grow during warm spells and sheltered valleys where warm-loving species could grow during ice ages. Here in North America, the Arcto-Tertiary forest eventually became limited to a little tract of mountain land spanning eastern Tennessee, eastern Kentucky, southwestern Virginia, and southern West Virginia.

After the glaciers finally receded, plants from the Appalachian refuge began to reforest the surrounding areas. Birches, beeches, and maples spread north into New England. Oaks and chestnuts were carried south and east by squirrels and Blue Jays while other oaks and elms ventured west into the drier prairies. But nearly every species retained a foothold here, making up the diverse cove hardwood forest.

Unlike other forest types that are named by their dominant trees --- oak-hickory and beech-maple, for example --- the cove hardwood forest is distinguished by its lack of dominant trees. Instead, dozens of species can be found growing side by side, many of them closely related to the trees that grew here 65 million years ago. Some of these trees, such as the Tulip-tree (also known as Yellow Poplar or Tulip Poplar), have relatives in only one other part of the world --- the mountains of eastern China. When I walk the northern leg of the Loop Trail, I inevitably get lost in my imagination, journeying over continents and through millions of years back to the Arcto-Tertiary forest that once dominated the northern hemisphere.

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