Jack Pine

A fleeting sunset flamed through a ragged stand of jack pines across our bay on Lake Two. Patchy clouds provided just substrate enough to catch the color, and the faint breeze barely ruffled their reflection on the lake. Here, on a classic rock knob campsite in the Boundary Waters, we perched above a scene of rugged beauty.

As it turns out, we were also perched on the border of the legendary Pagami Creek Fire. First detected on August 18, 2001, the smoldering burn stayed within a bog for days. When the relative humidity plummeted to 18% and a north wind picked up on August 26, the fire roared to life and swept through the forest’s crown. By November it had burned 93,000 acres, and sent smoke all the way to Russia. To protect the extremely popular, highly visited landscape of Lakes One and Two, the Forest Service completed a “burn out” operation between the fire and those lakes.

Looking at the maps, it’s quite likely that our view was part of the burn out, and our peninsula campsite was somewhat protected by their efforts. The point on the north side of the bay, now glowing with the sun’s last rays, was also spared. Its grove of jack pines are a respectable uniform height. While jack pines always look a little disheveled (like “something the cat dragged in,” joked my friend when helping us learn pine identification), at least these still had needles.

To the south, the skeletons of burned jack pines shimmered on the glassy lake, and the remains of their scraggly crowns scratched the sunset clouds at the same height as their more fortunate neighbors. Both stands probably started their lives after a past crown fire burned through an even older jack pine forest—although, with jack pines, it might be a little harder to tell if the burned or unburned half of the forest is more fortunate.

The unburned forest is getting up there in years, and has attained the average maximum height for jack pines of about 60 feet. Jack pines mature quickly, and maximum cone production begins at about age 20. The canopy shows signs of decay at only 75 years old. And while individual trees will survive up to 200 years (the oldest known jack pine was 243 years old, found in the Boundary Waters!), there isn’t much hope for a second generation of sun-loving jack pine seedlings under the stifling shade of the adults.

The charred skeleton of the forest is actually brimming with life. A thick carpet of 5-year-old jack pine seedlings, with a few aspen and birch mixed in, promises a bright future.

Jack pine is uniquely attuned to fire. Almost every burn that enters a jack pine stand will climb up the dry ladder of dead lower branches and become a stand-killing crown fire that provides seeds with full sunlight and a dose of fertilizing ash for expeditious growth. Flaky bark and resinous needles urge the fire on. In contrast, red and white pines self-prune their lower branches and grow thick, corky bark to prevent fires from crowning. They’re adapted to ground fires, which clear out competition, but allow old trees to thrive.

The key to jack pine’s dependence on fire, though, is its serotinous cones. Rather than referring to the sticky resin that glues the cones shut, serotiny simply means the trait of delayed seed release. Jack pine achieves this with a satisfying series of tricks.

First, the cones are glued tightly shut with resin, and may remain “in storage” on the tree for several decades. During their extended residence, the resin protects against seed predators like crossbills and squirrels, who make short work of the nutritious seeds in the cones of other species. When a fire finally rips through the forest, the resin ignites at a low temperature, and this relatively cool flame (only 112 degrees Fahrenheit!) helps prevent serious damage. The resin is stored in reservoirs within the cone, but only burns after it has traveled down a duct to the tip of the scale and encounters oxygen there, outside the cone.

Inside, corky material on the cone scales provides insulation for the seeds. The temperature gradient created from the outside-in causes the scales to curl back and open the cone like a flower. In fact, as our small campfire—composed mostly of jack pine twigs laden with tightly closed cones—crackled softly against the descending dusk, we watched in delight as the cones slowly “bloomed.”

Just that series of events is amazing enough, but jack pine’s cones go even further in their Rube Goldberg machine of adaptations. Although the cones open while the fire is still hot, the seeds stay safely stuck in the warm, gooey resin instead of dropping into an inferno. Only once the resin cools, shrinks, and cracks, do the seeds drop out—onto fresh, habitable soil.

What’s more, jack pines in fire-dominated areas produce almost entirely cones that open only with fire, while jack pines in the southern part of their range or on islands where fire is less prevalent, are adapted to opening just from the heat of the sun (a good thing, or else they might never open).

Sure, there is beauty in a colorful sunset “flaming” through the forest, but there is also beauty in the dance of fire, seeds, death, and rebirth when those flames are real.

Special Note: Emily’s book, Natural Connections: Exploring Northwoods Nature through Science and Your Senses is here! Order your copy at http://cablemuseum.org/natural-connections-book/.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! Our new phenology exhibit: “Nature’s Calendar: Signs of the Seasons” is now open.

The Pipes of Pan

A fleeting sunset flamed through a ragged stand of jack pines across the bay. Patchy clouds provided just enough substrate to catch the color, and the faint breeze barely ruffled their reflection on the lake. A biting chill in the air confirmed a more challenging forecast ahead. Here, on a classic, rock knob campsite in the Boundary Waters, we perched above a scene of rugged beauty.

A small campfire, composed mostly of jack pine twigs laden with tightly closed cones, crackled softly against the descending dusk as I pulled a book out of my portage pack. For this trip, I’d chosen Open Horizons, Sigurd Olson’s autobiography, which is filled with just as many lyrical scenes and philosophical meanderings as his other books.

I read the first lines aloud. “The Pipes of Pan sound early before the sense of wonder is dulled, while the world is wet with dew and still fresh as the morning.” And before I could begin the next sentence, a sweet, tooting call floated across the bay. The first time I heard the regular, almost mechanical, song of a saw-whet owl, I thought it was a car alarm or back-up beep. I learned my lesson quickly, though, and now perk up my ears on the rare occasion of this simple serenade.

Saw-whets are tiny owls, only as big as a robin, who are nonetheless tough as nails. They breed in the boreal forests of southern Canada, and the conifer forests of the northern and western United States. They are variably migratory, with some owls overwintering in their breeding territories, and others, especially from the far north, heading south. Their peak migration tends to coincide with leaf-off. This guy was right on time.

The owl ceased tooting after less than a minute, but before I could return to Sigurd, another sound cut through the dusk. This time it was the messy pattering of ducks taking off, and then the breathy whistling of wind through wings as a small flock of goldeneyes relocated out of our bay. Their distinctive flight sound has earned these compact, black-and-white ducks the nickname “whistlers.”

These interruptions to Sigurd’s musings on the Pipes of Pan seemed appropriate, since Pan and his pipes represent the harmonies of nature itself. In mythology, Pan is the half-goat Greek god of the earth who makes music with a set of reeds. “What I heard there were the Pipes,” wrote Olson, “and what I sensed, I know now, was the result of a million years of listening and being aware...”

This late fall trip was one of the quietest I’ve experienced in the Boundary Waters. Few other hardy souls braved the cold snap. Many birds had either migrated or fallen silent. The sounds we did hear, though, seemed more significant in their isolation.

At about 10:30 p.m., the quiet gave way to the patter of rain on nylon. Just before dawn, the sound changed distinctly to the harsh chatter of sleet, and then the soft swish of snow. Snow! The precipitation continued off-and-on all day. Happily, we were traveling with the wind, so the sleet simply hissed against our rain jacket hoods instead of stinging at our red cheeks. Neoprene gloves helped, but did not completely warm our hands. Portage landings were awkward, given the strong incentive to keep our feet dry. This is what outdoor adventurers often call “Type 2 Fun,” defined by The Mountain Training School as “not particularly enjoyable at the time, but rewarding after the fact.”

Although, there was something about the challenge—and certainly the swing of a paddle and the balance of a canoe—that was pleasurable in the moment, even against the cold. Sigurd Olson experienced pleasure in the face of discomfort, too, writing: “but for a moment the Pipes had sounded above the crashing of the waves…”

The weather did improve a little by our final day, and we enjoyed a calm, sunny afternoon listening to the clear whistles of a couple of gray jays, the chirping of an eagle, and the low, wild roar of a rapids in the narrows. That peaceful afternoon faded into one of the quietest nights I’ve ever spent in a tent, followed by a crisp dawn with every leaf edged in lacy frost.

The lake steamed silently as we made breakfast, and a flock of geese chattered amicably in the distance—their conversation slowly drifting southward. Not in a hurry to end our trip, we sat idly watching the mists swirl, our empty oatmeal bowls forgotten. In the absolute calm, I began to notice an occasional soft rustling sound. All around our campsite, birch leaves were detaching one-by-one and drifting to the ground. Not a whisper of breeze disturbed them, but perhaps the weight of the white rim of frost was enough to break them free.

“…and the Pipes were playing softly as they always do when a man has listened to their music and followed it to its source.”

Special Note: Emily’s book, Natural Connections: Exploring Northwoods Nature through Science and Your Senses is here! Order your copy at http://cablemuseum.org/natural-connections-book/.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! Our new phenology exhibit: “Nature’s Calendar: Signs of the Seasons” is now open.

Virginia Creeper

Brilliant blue sky and abundant sunshine greeted me at the Cable Community Farm. I’d been waiting for this—a perfect day to dig potatoes! Shovel, garden fork, and boxes clattered cheerily behind me in the little red wagon as it bumped over uneven paths. Stopping to open the garden gate, I took a moment to gaze appreciatively at the scarlet leaves of a Virginia creeper vine that had wound its way along the deer fence all summer.

A few weeks ago I admonished Albert Camus for thinking that fall needed to be a “second spring when every leaf is a flower," but Virginia creeper is a different case. One botany website describes its flowers as “insignificant.” Ouch! Honestly, though, I’ve never noticed the flowers. A quick search on Google Images shows that they are actually quite pretty, in a tiny, spritely way. The five-parted flowers are deep burgundy and pale cream, and grow in a grape-like cluster, eventually ripening into blue-black berries that are eaten by birds, mice, and other small mammals. Although, how much does their beauty count if you don’t ever see it? I just put a note in my calendar: next year, I’ll remember to look!

Virginia creeper’s fall colors more than make up for its inconspicuous July blossoms. Its starbursts of five gloriously vibrant red leaves (palmately compound leaves, technically) dominate all my memories of the plant. Growing up, we admired its color annually in the old fencerow below the house. A line of elm trees was dying and decaying in quick succession, and each tree was draped in more of the elegant vine than the last.

Those elm trees had bigger problems than a colorful vine, of course, but in some cases Virginia creeper can thread itself throughout the branches of a tree so thoroughly that it will shade the tree’s own leaves to death or add enough weight to hasten its downfall. On non-living substrates, like buildings, Virginia creeper is reported to be less damaging than non-native, invasive ivy. English ivy climbs using aerial root-like structures—appropriately called holdfasts—that wiggle their way into nooks and crannies and support themselves using adhesive nanoparticles. The holdfasts are exceedingly hard to remove, and excess moisture trapped against the wall can cause damage.

Perhaps because it is native, Virginia creeper isn’t quite so disparaged as a climbing nuisance. For one thing, it provides valuable habitat and hiding places for many small critters. The structure of its “holdfasts” also makes a difference. Its tendrils are tipped with tiny suction cups that flatten against the substrate and use the plant’s version of two-part epoxy to glue them securely in place. This structure eventually becomes woody and very weather-resistant, but is reportedly less damaging than ivy’s penetrating rootlets.

While the berries are toxic to humans and rubbing the stems or leaves on your skin may cause irritation, Virginia creeper is much less noxious than its most common look-alike. Especially when young, Virginia creeper is easily confused with poison ivy. While we all know the “leaves of three, let it be” rhyme that reminds us of a key characteristic of poison ivy, the five leaves Virginia creeper often unfurl sequentially. This means that at some point in the development of new leaf clusters they may only have three leaflets. Looking at the entire plant will help you make the correct identification.

Another mnemonic I just learned is “if it’s hairy, be wary.” This refers to the veritable fur of aerial rootlets that covers a poison ivy vine. Virginia creeper has those tendrils tipped with suction cups, but not in a density that would make it look hairy. I think we’re all pretty happy that it’s Virginia creeper and not poison ivy that’s twining itself along the deer fence at the Cable Community Farm!

A couple hours later, the little red wagon was once again bumping through the gate and under the glowing red garland of Virginia creeper. I was happy with my full box of purple potatoes, but overwhelmed by the 62 squash and pumpkins I’d also harvested from my garden plot. After loading it all in my car, I straightened my back, grabbed my camera, and went back to try and harvest just a little bit more of this perfect fall day.

Special Note: Emily’s book, Natural Connections: Exploring Northwoods Nature through Science and Your Senses is here! Order your copy at http://cablemuseum.org/natural-connections-book/.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! Our new phenology exhibit: “Nature’s Calendar: Signs of the Seasons” is now open.

Growing up before my eyes!

Water still dripped from the trees onto saturated duff, but blue sky peeked shyly through the clouds. Tired of the rain, my parents and I had taken advantage of a short break to go for a walk. Partway up the gravel road I followed a couple of mushrooms into the woods, and then looked up. Just above my head dangled a yellow and green sugar maple leaf with a squiggly line through it.

Immediately enamored (who wouldn’t be?), I plucked it down for a closer look. You may not think that animal tracking extends to insects, but you can use the same process of looking for clues that eventually tell a story. The squiggle on this leaf was typical of trails left by leaf miners, a group of insects (including moths, sawflies, flies, and beetles) whose larvae feed on the insides of a leaf between its “skins.” Some internet research and a quick email to Charley Eiseman, author of the fantastic resource Tracks & Signs of Insects and Other Invertebrates, and the “BugTracks” blog, turned up a narrative we can all relate to.

The story begins near the base of the leaf, where the trail of the leaf miner starts out narrow, about the width of a felt-tipped pen. The line itself is composed of a dark center stripe and paler, translucent edges. It records the growth—essentially the childhood—of a moth larva of the species Glaucolepis (Trifurcula) saccharella.

Photo by Steve Nanz.

The egg was laid earlier this summer, maybe about a month ago, by a tiny, brown-and-white moth—wingspan 4 mm. The larva hatched, burrowed its miniscule body in between the upper and lower epidermis of the leaf, and began to eat. What is there to eat between the skins of a leaf? A juicy substance called mesophyll fills this inner space. It is full of chloroplasts, the green engines of photosynthesis.

Like a mountain path, the narrow trail of the leaf miner scribed switchbacks in the lowest lobe of the leaf near the petiole before widening and flowing like a river toward the leaf’s tip. It was fascinating to follow that widening trail and imagine the larva growing bigger as it fed.

The line of frass (caterpillar poop) down the center of the trail tells its own story. Through much of the mine the frass is just a fuzzy brown line, but in some sections a zigzag pattern becomes visible. It looks for all the world like one of the fancy stitches on my sewing machine. Charley Eiseman explained the cause of this pattern in an email. “It's mesmerizing,” he wrote, “to watch a nepticulid larva at work under magnification—the central frass line is made up of many tiny pellets, and the larva is constantly depositing them as it eats, wiggling its tail end around methodically to place them just so.”

When I read that, you can bet I added “watch a leaf miner larva at work” to my bucket list!

Looking at my leaf, I can just imagine the absolute concentration of the larva as it went about its essential business of eating, and necessary business of pooping. Occasionally, though, the pattern seems to break. There’s a slight accumulation of frass, then a thinner line, and—is it my imagination?—after that the entire mine seems to get a tad wider. I suspect that these interruptions in the pattern indicate places where the caterpillar got too big for its skin and molted, becoming a new “instar.”

Just before the end of the mine, its color changes drastically. I noticed it first on the LCD screen of my camera. I had just taken a photo of the leaf backlit by the sun. Most of the mine lit up beautifully, like a stained glass window. Near the tip of the leaf, though, the mine around the frass line became completely invisible! Turning the leaf over, I noticed that the color on the back side also changed drastically at that point. For most of the mine, it was apparent that a layer of leaf was more intact on the lower side of the mine than the upper. Then, for the last stretch of the mine, the insides of leaf seemed to be completely hollowed out. The frass line appeared thinner and straighter, too, like the path of someone on a mission. My hunch is that on the final day before its metamorphosis, the larva suddenly became a ravenous teenager and started eating everything in reach, and eating it so fast that the frass line stretched thinner, like a line from a pen swooped lightly across a page.

Finally, maybe a quarter inch from the end of the mine, the frass line ends. The mine continues as a transparent section of leaf, missing all its green. This, Charley confirmed for me, represents the length of the larva—frass marking one end, un-eaten leaf marking the other end—just before it popped out of the leaf, dropped to the ground, and formed a cocoon to overwinter before completing its metamorphosis to a moth next spring.

“Watching” the process of this larva growing bigger, and bigger, and finally leaving home to metamorphose reminds me of all the little old ladies I grew up with who would pinch my cheeks lovingly and admire how I’d grown. Then they’d hold up their thumb and first finger about an inch apart and exclaim “I’ve known you since you were this big!” If I could find that tiny larva, now wrapped tightly in its cocoon, you can bet I’d pinch its cheeks, too! After all, I feel like I just watched it grow up before my eyes.

Special Note: Emily’s book, Natural Connections: Exploring Northwoods Nature through Science and Your Senses is here! Order your copy at http://cablemuseum.org/natural-connections-book/.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! Our new phenology exhibit: “Nature’s Calendar: Signs of the Seasons” is now open.