The Forest Unseen: A Year's Watch in Nature (7 page)

In the mandala, the rain continues its pounding. From where I sit, I hear two streams roaring, one on either side of the mandala, both at least a hundred meters away. The rain’s volume has turned the sound of their usual quiet trickle to a thundering roil. After an hour or more of huddling in my waterproof clothes, I feel oppressed by the incessant violence. But the mosses seem more at home than ever. Five hundred million years of evolution has given them mastery of wet days.

A
leg flashes across a crevice in the leaf litter. The stub of a tail follows and then disappears into layers of wet leaves. I resist the urge to peel away the leaves; instead I wait, hoping that the salamander will surface again. Several minutes later, a shining head thrusts out, and the salamander sprints into the open. It pushes down another hole, reappears, bursts into a run, trips over a leaf stem, and somersaults ungracefully into a hollow. Shaken, the salamander rights itself and climbs out of the depression, finally ducking its head to slide under a dead leaf. Cold mist thickens the air, and I can see only a few feet ahead of me, but the salamander shines as if it were illuminated by a clear ray of sunlight. The dark, smooth skin is freckled with silver. Small red streaks flow down the animal’s back. The skin is impossibly wet, a cloud condensed into animate matter.

Like mosses, salamanders thrive on moisture, but salamanders cannot use the mosses’ strategy of drying up and waiting out the days between rains. Instead, they follow cool, humid air like nomads, moving in and out of the soil as the humidity changes. In winter they creep down between rocks and boulders, escaping the freeze and living as troglodytes in the subterranean darkness, up to seven meters belowground. In the spring and autumn they climb back up and ply the leaf litter, pursuing ants, termites, and small flies. Summer’s drying heat pushes them back underground, although on wet summer nights salamanders burrow back to the surface to feast without danger of dehydration.

The salamander is twice as long as my thumbnail. Its neck and legs are slender, marking it as a member of the genus
Plethodon
, perhaps a zigzag salamander or a southern redback. The fact that all
Plethodon
species are variably colored and poorly studied reinforces the imprecision of my identification. Then again, no one is quite sure what a salamander “species” really is, which suggests that nature doesn’t conform to our desire to draw firm lines.

The salamander is small, so it is likely a juvenile, hatched late last summer. Its parents courted last spring, with delicate footwork and tender cheek rubbing. Salamander skin is a patchwork of scent glands, so the cheek rubs convey chemical whispers and pheromone love poems. When the couple has become acquainted, the female lifts her head and the male slides under her chest. He walks forward and she follows, straddling his tail in a conga dance for two. After a few steps, he deposits a small cone of jelly topped with a packet of sperm. He moves forward again, waggling his tail, and the female follows. She stops and uses her muscular vent to pick up the sperm. The dance breaks up and the salamanders wander on their separate ways, never to interact again.

The female seeks out a rock crevice or hollow log in which to lay her eggs. She then wraps herself around them, remaining in the nest hole for six weeks, longer than most songbirds sit on their eggs. She rotates the eggs to stop the developing embryos from sticking to the sides. She also eats any egg that dies, preventing mold from growing and killing the whole clutch. Other salamanders may visit the nest hole, looking for an egg snack, and the brooding mother chases them off. Motherless broods invariably get infected by fungi or eaten by predators, so this vigil is crucial. Once the eggs hatch, her parental duties are finished, and the mother will renew her depleted energy reserves by feeding in the leaf litter. The young salamanders are miniature versions of the parent and strut across the forest floor, feeding themselves without assistance. The
Plethodon
scuttling across the mandala therefore lives its whole life without dipping a toe into a stream, puddle, or pond.

This breeding process demolishes two myths. The first is that amphibians are dependent on water for breeding—
Plethodon
is a nonamphibious amphibian, as slippery to classify as it is to hold. The second myth is that amphibians are “primitive” and therefore don’t care for their young. This latter fallacy is embedded in theories about the evolution of the brain claiming that “higher” functions such as parental care are confined to “higher” animals such as mammals and birds. The mother’s careful vigil shows that parental solicitude is more widely spread in the animal kingdom than hierarchical brain scientists suppose. Indeed, many amphibians care for their eggs or their young, as do fish, reptiles, bees, beetles, and a menagerie of doting “primitive” parents.

The juvenile salamander in the mandala will spend another year or two feeding in the leaf litter before it is large enough to become sexually mature.
Plethodon
sets to this task of feeding with carnivorous gusto. Salamanders are the sharks of the leaf litter, cruising the waters and devouring smaller invertebrate animals. Evolution has discarded
Plethodon
’s lungs to make its mouth a more effective snare. By eliminating the windpipe and breathing through its skin, the salamander frees its maw to wrestle prey without pause for breath.
Plethodon
has struck a deal with evolution’s Shylock: better tongues bought with a few grams of lung. The salamanders are living it up on their three-thousand-ducat loan, conquering the wet leaf litter across the eastern forest. The gamble is paying off at present, but the usurer may yet call in the debt. If pollution or global warming changes conditions in the leaf litter,
Plethodon
species will be ill suited to cope. Indeed, projections of habitat change caused by global warming suggest that mountain salamanders will suffer major declines as their cool, wet habitats disappear.

No one knows how
Plethodon
salamanders arrived at their lungless condition. Their relatives all have lungs, although those that live in mountain streams have rather small lungs. Cold streams have plentiful oxygen, so stream-dwelling salamanders can use their skin as a breathing
organ. Perhaps the terrestrial lungless salamanders evolved from these stream-dwelling kin? This was biologists’ favorite explanation until researchers looked more closely into the geological record. The rocks told an inconvenient story: the eastern mountains were small undulations when
Plethodon
salamanders evolved. Such gentle inclines could not have produced the cold, rapid streams inhabited by the small-lunged salamanders. So, we are left without a historical narrative for the
Plethodon
’s lungless condition.

The mandala is almost large enough to contain the whole world of this animal. Adults are territorial and rarely stray more than a few meters; some individuals move farther downward into the soil than they do across the surface of the litter. This rootedness accounts for the diversity of woodland salamanders. Because they seldom move far, the salamanders on different sides of a mountain or valley are unlikely to interbreed. Local populations therefore adapt to the particularities of their habitat. If this divergence keeps up for long enough, separate populations may come to look different and have different genetic characteristics. Some may even get called different “species,” depending on the current taxonomic fashion. The Appalachian Mountains are ancient rocks, and their southern end, where the mandala sits, has never been covered by a killing sheet of ice-age glaciers. The salamanders here have therefore had time to explode in a burst of diversity that is unmatched anywhere on the planet. This diversity partly accounts for why salamanders are so difficult to classify into species.

Unfortunately for the salamanders, the old wet, warm forests that produced salamander diversity also grow large, profitable trees. If these trees are removed in large clear-cuts, the shady leaf litter turns into a sun-beaten crisp, killing all the salamanders. If the clear-cut is lucky enough to be surrounded by mature forest, and if it is left alone for several decades, salamanders will slowly return. But the salamanders do not return to their former abundance, although no one knows why. Perhaps large clear-cuts eliminate genetic fine-tuning from local populations? Logging also removes trees that would have fallen to create
moist crevices, nesting holes, and refuges from the sun. The scientific jargon for these life-giving fallen trees is “coarse woody debris,” a term that seems too dismissive for such a life-giving part of the forest’s ecology.

The salamander in the mandala thrives among the messy tree falls in this small protected patch of old-growth forest, but although clear-cuts are unlikely, the animal is not free from danger. This salamander is tailless, probably the result of an encounter with a mouse, bird, or ringneck snake. When attacked, salamanders thrash their tails to divert the predator. If needed, the tail will break off and undulate violently, providing distraction while the salamander escapes. The blood vessels and muscles at the base of
Plethodon
tails are specially adapted to clamp shut once the tail is lost. The base of the tail also has weaker skin and is constricted, presumably to help the tail break free without hurting the rest of the body. Evolution has therefore struck two bargains with these animals, both secured with flesh: better mouths bought with lunglessness and longer lives bought with detachable tails. The first deal is irreversible; the second is temporary, erased by the mysterious regenerative power of the tail.

Plethodon
is a shape-shifter, truly a cloud. Its courtship and parenting defy our haughty categories, its lungs were traded for stronger jaws, its body parts are detachable, and it is paradoxically moisture loving yet never enters bodies of water. And, like all clouds, it is vulnerable to strong winds.

T
he temperature has been warm all week, giving us an unseasonable but welcome foretaste of May. The first spring wildflowers have sensed the change and have pressed up from below the litter, causing the formerly smooth mat of dead leaves to buckle as the stems and buds of flowers elbow through.

I shed my shoes for the first part of my walk to the mandala, treading barefoot on the worn public foot trail, feeling the ground’s mild warmth. Winter’s sharpness is gone. As I walk in the gray predawn light, birds are in full song. Phoebes rasp from the rocky bluff, accompanied by titmice whistling from low branches and woodpeckers cackling from large trees below the trail. Aboveground and below, the season has turned.

At the mandala, I find that one flower bud, a
Hepatica
, has finally pierced the litter, standing on a finger-high stem. A week ago, the bud was a thin claw, encased in silver fuzz. Slowly, the claw filled out, fattening and elongating as the air warmed. This morning, the bud’s stem is shaped like an elegant question mark, still covered in down, with the tightly closed flower suspended at the tip of the curve. The flower points demurely down, its sepals closed against nighttime raiders of pollen.

The flower cracks open an hour after first light. The three sepals spread, revealing the edges of three more inside. The sepals are flushed with purple and, although
Hepatica
lacks true petals, these sepals have
the shape and function of petals, protecting the flower at night and attracting insects by day. The flower’s opening motion is too slow for my eyes to perceive directly. Only by looking away then returning my gaze can I see the change. I try to still my breathing, slowing to flower-speed, but my brain races too fast, and the slow, graceful motion eludes me.

Another hour passes and the stem straightens; the question mark turns into an exclamation point. The sepals are spread wide now, shining rich purple at the world, inviting bees to investigate the untidy mop of anthers at their center. One more hour and the exclamation point is written in a hurried hand, bent backward a little, lifting the flower’s face directly at me. This is the mandala’s first bloom of the year. The lively skyward arch of the flower’s stem seems a fitting gesture of springtime release and celebration.

The flower’s name,
Hepatica
, has a long history, one that reaches back to Western Europe where a close relative of the same name has been used in herbal medicine for at least two thousand years. Both the scientific name and the common name, liverleaf, refer to the plant’s purported medicinal qualities, suggested by the three-lobed liverlike shape of the leaves.

Most of the world’s cultures have a habit of extrapolating from the shapes of plants to their medicinal powers and hence to their names. In the Western tradition, this habit was codified into a theological system by an unlikely scholar. In 1600, a German cobbler, Jakob Böhme, experienced a stunning vision of God’s relationship to creation. The heart-ripping magnitude and power of this revelation tore him away from his shoe-making trade and thrust a quill into his hand. Out flowed a book, a stream of words attempting to communicate the massive wordless vision. Böhme believed that God’s purpose for His creation was signed into the forms of worldly things. Metaphysics was scrawled into flesh. He wrote, “Every thing is marked externally with
that which it is internally and essentially… [and] represents that for what it may be useful and good.” Mortal, imperfect humans could therefore deduce purpose from the outward appearance of the world and could see the thoughts of the creator in the shapes, colors, and habits of His creation.

Böhme’s work caused his expulsion from his hometown, Görlitz. The church and the city council would not tolerate unauthorized mystical experiences. Shoemakers, they felt, should stick to cutting leather and leave visions to the well-read and the well-bred. Later, he was allowed to return on the condition that he keep his quill away from paper. He tried and failed, the vision’s power pushing him on to Prague, where he continued his theological essays.