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Joyce Kilmer Memorial Forest

/ Mike Fitz / 5 Comments

Old growth forests in the eastern U.S were formidable barriers to colonization, places to be subdued and civilized, to fuel industrialization, not preserved. Today, we view old growth forests differently. They give refuge to rare species, support diverse ecological communities, and often provide the conditions necessary for trees to attain their maximum size and age. While visiting Joyce Kilmer Memorial Forest in the Nantahala National Forest, I thought about why these forests remain so important despite the some negative changes they’ve recently undergone.

Prior to European colonization, forests in the eastern U.S. formed a mosaic of complex habitats, owing to natural disturbance regimes and the influences of American Indian nations. An unbroken old growth canopy stretching for the Atlantic Ocean to the Mississippi River is mythical and never existed. Lightning-caused fires, human-caused fires, tornadoes, ice storms, hurricanes, and insects imparted constant change. Some forests were likely disturbed every few decades at minimum, while others grew undisturbed for hundreds of years.

Joyce Kilmer Memorial Forest is one of those places that grew relatively undisturbed. It is a pocket of old growth tucked away in the rugged mountains of western North Carolina. While many impressive trees grow here, the most impressive and largest trees are Liriodendron tulipifera, the tulip tree. Also known as tulip-poplar or yellow-poplar, tulip trees grow fast and tall (the tallest individual tree in the eastern U.S. is currently a tulip tree) and are easy to identify in summer because of their distinctively-shaped leaves.

No live leaves hung from the tulip trees on the overcast, early January day when I visited, but this allowed me to contemplate the trees’ full scale. The tulip trees at Joyce Kilmer are the largest of the species that I’ve ever seen. Many exceed 15 feet in circumference at chest height, approach 150 feet tall, and are several hundred years old.

person standing at base of large tree

I was impressed by complex crowns of the largest trees. Most trees in the eastern U.S. today don’t attain such large, complex crowns. They simply aren’t allowed to grow long enough. Many of the crowns were scarred and broken by centuries of battles with wind, ice, and other forces that try to break the tree down.

crown of large tulip tree

Since tulip poplars are intolerant of shade, the largest tulip trees at Joyce Kilmer likely sprouted and began to dominate the canopy after a major disturbance, like a fire or tornado, swept through the area several hundred years ago. The now towering tulip trees effectively shade the understory, suppressing the germination and growth of their offspring. Instead of young tulip trees, the understory of the forest was filled with more shade tolerant species like sugar maple and American beech. In a couple of hundred years future visitors may see giant sugar maples growing over the decaying remnants of tulip poplars.

Despite the beauty and stateliness of the trees at Joyce Kilmer, this isn’t forest primeval. No such thing exists in the eastern U.S. Evidence of significant, human-caused changes are easy to find here. Until recently, Joyce Kilmer Memorial Forest contained many large eastern hemlock trees. Now, however, almost every hemlock tree in the grove has been killed by hemlock woolly adelgid, a non-native, invasive insect that basically sucks starch out of the hemlock. I found only a handful of live hemlocks in the grove, and none were particularly large.

dead hemlock trees

These hemlocks were killed by hemlock woolly adelgid.

Disturbed, young forests are easy to find. Joyce Kilmer Memorial Forest is different. It represents the forests which used to exist and provides examples of the threats forests face today. The tulip trees at Joyce Kilmer are massive, dwarfing almost everything there, especially me. I walked under the trees in wonder even though this place is very changed. I can’t pretend this is the same forest with the same species composition as it was even a hundred years ago. Among other changes, the hemlocks are dead or dying, American chestnuts are functionally extinct, and passenger pigeons no longer darken the skies. Still, I don’t want to demean this place as less special because it’s not what it once was. On the contrary, it is more special because forests like this are so rare.

person standing at base of large tree

Sometimes Individuals Lose While Species Win

/ Mike Fitz / 10 Comments
pine cones on the ground

Many seeds in these cones wait to be released.

Fire is a boon to some species and a detriment to others. When fire sweeps across the landscape there are winners and losers.The cones of lodgepole pine (Pinus contorta) demonstrate adaptations that allow the species to survive potentially catastrophic changes.

Serotiny is an adaptation of some plants to release seeds in response to an environmental trigger. Serotiny is expressed in lodgepole pine through its cones. In fire prone habitats, lodgepole pine cones are glued shut by resin. Heat from fires melts the resin allowing the cone scales to separate and release seeds. Since it’s not safe to watch a wildfire burn through lodgepole pines, I placed a tightly sealed serotinous cone from a lodgepole pine in a toaster oven to watch how it responded to temperature changes.

The cone scales began to expand noticeably when the temperature reached about 50˚C (122˚F).  According to the U.S. Forest Service, more precise lab experiments have found the resinous bonds between the cone scales begin to break between 45˚C and 60˚C, so serotinous cones lying at or near the soil surface can also open with these ground temperatures. If this cone was kissed by fire its scales would have expanded and allowed the seed to be slowly released. (I let the temperature in the oven rise to over 200˚C (400˚F) just because I felt like watching the scales fully expand.) Serotinous cones collect on the ground or on tree branches for many years. The seeds under the scales lie in a state of dormancy, waiting for the opportunity to sprout.

Not all stands of lodgepole pines have serotinous cones. Serotinous cones are not common in eastern Oregon, rare in coastal populations, absent in some fire prone habitats like the Sierra Nevada, and “many stands in the Rockies have less than 50 percent serotinous-cone trees.” Wherever it grows through, lodgepole pine thrives in full sun. Its seeds sprout best in or on bare mineral soil and disturbed duff free of competing vegetation—the exact conditions many fires create.

small pine trees under taller, dead-standing trees

After huge wildfires burned large swaths of Yellowstone National Park in 1988, lodgepole pine sprouted back in earnest. This NPS photo was taken ten years after the ’88 fires. The lodgepole trees are much larger now.

Serotiny in lodgepole pine makes large quantities of seeds available to germinate following a fire. In many cases, especially regarding lodgepole pines, fire may be an enemy to the individual, but not to the species.

The Best Thing You’ll Read About Bark Today (If You Don’t Read Anything Else about Bark)

/ Mike Fitz / 6 Comments

Black bear claw marks on quaking aspen, Beaver Ponds Trail.JPG

This post is about bark.

I know what you’re thinking. “Bark—an enthralling topic!” I couldn’t agree more, but bark is often overlooked and ignored by most people. Yet bark records many events in a tree’s history.

Thin and smooth barked trees like quaking aspen (Populus tremuloides) are especially good at recording animal sign. Aspen is the most widely distributed native tree in North America. Its bark becomes thick and furrowed only on old trees, and usually only near the ground. Most of the time aspen bark is smooth, colored white to gray (even greenish on young trees) with dark chevrons where self-pruned branches fell to the ground.

Since aspen bark is thin-skinned, it’s easily scarred. Along hiking trails, you’ll commonly find names and initials carved into it. (Don’t do this. No one cares if you were there with your “true love,” who you probably dumped the week after, and it opens the tree to possible infection.) Aspen bark records more than human impulses though. In bear country, you can often find evidence of bears climbing the trees.

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Black bears have five toes each equipped with claws superbly designed for climbing. Scars on trees from climbing bears usually come in sets of five.

Black bears are particularly adept at climbing trees. Their strength and relatively short, sharply curved claws help them gain purchase even on smooth barked trees like aspen. If I’m in an area where black bears live, I almost always look for bear claw marks on aspen. In the Stehekin Valley, bear claw marks are easily seen on aspen along the Stehekin River Trail and Agnes Gorge Trail.

The claw marks represent a moment in time. Under what circumstances were they made? Was a bear startled by a person? Another bear? Was it simply playing or exploring? Black bears are omnivorous, but I have read no records or seen any signs of them eating any part of aspen trees, so they probably weren’t climbing the tree for food. In the eastern U.S. though, black bears often climb another smooth barked tree, American beech (Fagus grandifolia), to feast on beechnuts.

The next time you find an aspen, take a closer look at its bark. Bark isn’t as static as its outward appearance suggests. You might find a story there.

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