Saturday, April 29, 2017

Old-Growth Forests of the Smokies

Have you ever wondered what early pioneers saw when they first encountered the aboriginal temperate forests of eastern North America? How lucky were the Scots-Irish "Ulstermen" who found refuge within the very same mountain range they emigrated from during the 1700s - their dialects, whiskey, music, and might continue to flow through the southern Appalachians. How devastating it must've been for the thousands of Cherokee Indians who were forced away from such a spiritual masterpiece during the trail of tears, and the range of management practices that have since ravaged the landscape. The Great Smoky Mountains National Park (GSM) has undergone great change in the past 200 years, but remains the largest example of the biologically diverse Arcto-Tertiary geoflora in the world, home to large swaths of old-growth forest. 
This past weekend, I had the pleasure of taking a trip through time to explore some of the many old-growth forest patches in GSM. Of the 500,000 acres of land, roughly 100,000 are considered old-growth forest and, with only ~4% of original forest remaining in North America, GSM is undoubtedly a special place worth conserving for future generations. Although we have all come across large trees in the woods, there is something uniquely different about old-growth forests that few will ever witness.



Today, we understand the term "old-growth" to be synonymous with virgin forest, primary forest, primeval forest, and the like. Generally, they are characterized as attaining great age without significant disturbance, and thereby exhibits distinct ecological properties. Since archival records do not exist for some tracts of land at GSM, it is impossible to understand the exact legacy of land within the park. However, the tracts I visited were previously cored and aged to over 250 years old and signify some of the most pristine old-growth remnants of temperate deciduous forest in the country. Of the 28 main watersheds in GSM, only 6 contain old-growth patches - I visited patches in the Roaring Fork, Little Prong Little Pigeon River, and West Prong Little Pigeon River watersheds.

The park is home to five main community types, including the Spruce-Fir forest, which dominates the highest elevations >4,500 feet, and has the largest unbroken tract of old-growth red spruce forest in the world; Northern Hardwood forest, composed of many species typically found in New England; Hemlock forest, which has greatly been affected by the exotic insect, Hemlock Wooly Adelgid; Pine and Oak forest, existing in the driest areas; and the Cove Hardwood forests that not only exhibits the greatest species diversity, but make up over 80% of the park area. 

Besides the obvious difference in tree size upon entering old-growth patches, there were other attributes characteristic of undisturbed forests. For example, the structure seemed to be clearly stratified compared to younger forests, defined by a distinct separation between the ground, sapling, sub canopy, and canopy layers. I also noticed an increase in sheer diversity at all levels, and evenness in the tree canopy. In other words, there seemed to be far more species in older forests, with numerous co-dominant tree species in the canopy versus younger forests characterized by a dominance of one or two prolific species. Further, I didn't see one exotic plant species.


The GSM has over 10,000 documented species, and over 100 tree species within the park, and since the first published flora in 1964 by H. L. Hoffman, there have been over 1600 plant species found. In the Cove Hardwood forest patches I encountered, the canopy was mostly comprised of massive yellow buckeye (Aesculus flava), Carolina silverbell (Halesia carolinia), and tuliptree (Liriodendron tulipifera). Aside from composition, the trees are noticeably larger and taller with moss covered trunks. The soil is loose, moist, rich, and uneven due to pitfall gaps from fallen trees, with large fallen logs strewn about that act as nurse logs for numerous species. Although trees in the temperate forest often have taproots and a lack of prominent buttresses, as opposed to many tropical trees, I found buttressing on all old-growth trees I encountered, which help support their increased height and size. 

As I ate lunch below the tall canopy in the Cove Hardwoods forest, I took in the vibrant chorus of spring migrants such as the worm-eating warbler, warbling vireo, blue-headed vireo, cerulean warbler, and many more, while cautiously scanning the horizon after finding multiple instances of bear sign. In the old-growth Hemlock forests, black-throated green warblers kept me company, as I navigated through a labyrinth of rosebay rhododendron (Rhododendron maximum) at the bases of gigantic eastern hemlock (Tsuga canadensis) and sugar maple (Acer saccharum). Sadly, many of the hemlock trees have already succumbed to HWA, but some remain.

Having visited many other forests throughout the country, there is something intrinsically nostalgic to me about an undisturbed, old-growth woodland in eastern North America. They are well protected gems that are nearly extinct. Upon entering, I felt as if I was viewing the world through the eyes of an ancient denizen from a simpler time. Beneath the neon new-growth of this rich mesic forest did I find a deep respect not only for the ancient organisms that have persisted through luck and mercy, but also for the sad story of the natives, and the immigrant mountaineers that lived tough lives, or the calloused CCC men who helped build this country - this forest is a living history of North America. The cool, misty understory, vibrant bird songs, colorful spring ephemerals, and cultural connection is nearly indescribable, but eternally unforgettable. 

Even today, after almost a century, we would be wise to remember the words of Franklin D. Roosevelt when he designated the Great Smoky Mountains National Park in 1940: 

"We used up or destroyed much of our natural heritage just because that heritage was so bountiful. We slashed our forests, we used our soils, we encouraged floods, we overconcentrated our wealth, we disregarded our unemployed - all of this so greatly that we brought rather suddenly to face the fact that unless we gave thought to the lives of our children and grandchildren, they would no longer be able to live and to improve our American way of life."