Heaven in the Northwoods

Note from Emily Stone: I’m so excited that Heaven has joined our Museum team! In between teaching MuseumMobile programs in schools, organizing spring field trips, and leading Junior Naturalist Programs, Heaven will be guest writing for Natural Connections about once a month. I’m looking forward to following her journey of discovery in the Northwoods!

Heaven Walker, Educator/Naturalist at the Cable Natural History Museum, will be guest writing for Natural Connections about once a month. Photo by Emily Stone.

The wonders of nature have fascinated me from a young age. Now I strive to understand the intricate natural workings of each place I live or visit. Cable, Wisconsin, is my newest place of interest. As the new Educator/Naturalist at the Cable Natural History Museum, I will get to use my fascination with the environment to connect both myself and the public with Northwoods nature.

From the rolling hills of southern Iowa where I grew up, to the Black Hills of South Dakota, and the coasts of South Carolina where I’ve worked, I strive to know the ecosystem in which I live. What new trees and wildflowers can I learn? Where can I find a new natural community to explore? What new animals can I observe? How do the animals interact with their natural habitat, and how do the local people interact with them? I love being a student of the land, connecting with the organisms who live there, and discovering how they all come together.

Now, in the Northwoods, I am itching to get out and start exploring. Guidebooks and online resources are fantastic for supplying information, but to really get to know a place you need to immerse yourself in it. That is exactly what I plan to do here.

For example, through reading I learned that bogs are acidic because of the sphagnum moss that grows there. This acidity results in a unique assemblage of carnivorous plants, cotton grass, and stunted black spruce. I cannot wait to get out and see the sphagnum moss that carpets the floor and search for the bug-eating pitcher plants, sundew, and bladderworts.

I am most eager to get to know the native trees who inhabit the Northwoods. One way I have been introduced to the tree species here is by working on the upcoming exhibit “Becoming the Northwoods” for the Museum. The Northwoods are the transition zone between the boreal forests of the north, and the deciduous forests of the south. Here, conifers like balsam fir who are at the southern extent of their range, mix with deciduous species like sugar maples in their northern reaches. This gives the Northwoods a beautifully unique blend of trees.

In contrast, my southern Iowa childhood was full of deciduous trees, while the only conifers I grew up with were red cedars. I was excited to see all the pines as I moved to the Northwoods! Now I am eager to meet them all, and to understand their place within this community.

Though the abundance of new plants I have yet to discover is exciting, the thought of getting to occupy the same place as wolves and black bears is thrilling. In Iowa, European settlement and expansive agriculture have pushed many wildlife species out of the state. Pre-settlement, black bears and wolves both roamed the prairies and forests. However, it is highly unlikely black bears or wolves will ever inhabit Iowa again; there are not enough wild spaces.

But up in the Northwoods, the vast forested areas have allowed wolves and black bears to cohabit alongside people. I am eager to learn all the ins and outs of sharing their space. I would consider myself lucky to get to see them.

My life in the Northwoods will bring a new adventure at every turn, and present numerous opportunities to learn. I am excited to discover this wonderful place and everything it has to offer. From hiking trails to wildlife encounters and interesting ecosystems, I am eager to get outdoors and learn about my new home. Let’s just hope the mosquitos don’t carry me away!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum’s current exhibit “Anaamaagon: Under the Snow” is open through March 11. The Museum will be closed for construction March 12 through April 30. Our Winter Calendar is open for registration! Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Black-backed Woodpecker in the Bog

“It’s here.” My partner and I had barely stepped out of our car when another birder, perhaps getting a fresh camera battery from his car, confirmed the sighting we’d seen posted online. “Take the left fork on the boardwalk,” he added. And then, “You can follow me.”

We slung our much smaller cameras around our necks and prowled down the Bob Russell Memorial Boardwalk behind him into Winterberry Bog. This sweet little forest, trail, and parking lot is part of the Sax-Zim Bog Important Bird Area about an hour northwest of Duluth, Minn. Here, on about 300 square miles of public and private land, the clay soils of an old glacial lake plain hold water, and the cold, wet climate has perpetuated a thick layer of peat on top.

Bog species such as sedges, tamaracks, and black spruce give the landscape a scraggly look, and open areas provide good hunting grounds for rare species of owls. Aspen uplands, rivers, lakes, meadows, and farms join in the patchwork. According to the Friends of Sax-Zim Bog at saxzim.org, it’s a “’magic mix’ of habitats that boreal birds love.”

Although the tamarack trees along the boardwalk lacked the green needles that clothed their neighboring spruces, that was to be expected. Tamaracks, also known as the eastern larch, or Larix laricina, are a deciduous conifer. In an unusual combination, these trees have needle-like leaves and bear their seeds in cones like spruces and pines, but they lose their leaves in the fall like maples and grow them back each spring.

Signs of life did eventually appear, revealed by motion among the tree trunks. A few people dressed in bulky winter gear and peering through a spectrum of optical equipment from giant camera lenses to modest binoculars stood on the boardwalk. Everyone was focused low on the trunk of a tamarack tree only a few feet away.

I hardly needed to zoom in to see the bird’s black head, white face with black stripe, black-and-white barring on their flanks, and solid black back. Five years ago I’d seen an almost identical woodpecker in this same bog, but that one had a stripe of white down the middle of their back identifying them as a three-toed woodpecker. This was their cousin, a black-backed woodpecker.

I saw this three-toed woodpecker in the same bog in 2020. Photo by Emily Stone. 

Black-backed woodpeckers like this one have just three toes, while most woodpeckers have four. They grip tightly to bark while prying off flakes to get at beetle larvae underneath. Photo by Emily Stone.

Both species specialize in peeling flakes of bark off dead or dying trees to get at the plump, juicy larvae of wood-boring beetles. They often forage in burned areas, blowdowns, flood-damaged forests, and other places where insects have moved in. Here, the eastern larch beetle has provided them with a giant and long-lasting buffet.

This tamarack tree has been infested with eastern larch beetles. Black-backed woodpeckers are now prying off flakes of bark to get at the beetle larvae, leaving the snow beneath covered in litter. Photo by Emily Stone.

Eastern larch beetles are native to the United States, and have always produced small and short-lived outbreaks. Since 2000, though, Minnesota has seen 20 consecutive years of outbreaks, with more than 440,000 acres infested, and no end in sight. Climate change is implicated in the beetles’ surge.

Adult beetles emerge in spring, find a new tree to infest, burrow into the bark, mate, and lay eggs. The mother beetles go on to deposit one or two more clutches of eggs. In the past, these “sister broods” didn’t have time to fully develop before winter. Longer growing seasons now allow more beetles to reach maturity each year, and warmer weather results in less mortality for the overwintering larvae. It’s a perfect storm, and forest pathologists have not found a cure.

Flakes of bark rained down gently and scattered on the snow beneath the woodpecker’s perch in the dying tamarack. As I watched, the bird craned her neck to the side and wedged her beak under a loose piece of bark. A quick chipping motion soon freed the flake. This distinctive foraging style is characteristic of both black-backed woodpeckers and three-toed woodpeckers. They rarely excavate deep holes. When your lunch wiggles just under loose bark, there’s no need.

While many birds find food in Sax-Zim Bog, people come here to find the birds. This is a southern outpost for many beings typically found farther north. Protected areas like Winterberry Bog and a welcome center run by the Friends of Sax-Zim Bog have facilitated easy access to unusual species for a whole community of people interested in observing the interplay of life and death in nature. In the words of the helpful birder “It’s here!”

Author’s Note: Portions of this article are reprinted from 2020.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum’s current exhibit “Anaamaagon: Under the Snow” is open through March 11. The Museum will be closed for construction March 12 through April 30. Our Winter Calendar is open for registration! Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

The Breeze of Balance

After I silenced the beep of my alarm clock, the sound I noticed next was the wind roaring through the forest and around the eaves. It was not the first howling wind of this winter. Sometimes it wears on me—the constant battle, the whipping hair, and the unceasing noise—but some days it is invigorating and refreshing. What do you love or hate about the wind?

Wind crashes waves into rocks and ice at the mouth of the Cascade River on the North Shore of Lake Superior. Photo by Emily Stone.

The wind can be a symbol of unity, freedom, eternity and balance. It is as true ecologically as it is metaphorically.

The first time I encountered wind as a symbol of unity, I was on the south shore of Lake Superior, at a wedding on a piney point. A stiff breeze whipped through the trees and blew out the unity candle. With great aplomb, the minister launched into a beautiful and extemporaneous sermon on the wind as a symbol of unity. As the air swirled around all the guests and the happy couple, we imagined how our breaths came from and returned to the one body of air that surrounds us and the entire globe.

In some cultures, wind is personified as a divine messenger who is able to manipulate unseen energy. Indeed, wind is the main way that our Earth attempts to equal out differences in temperature. Energy from the Sun warms the Earth and the air above it, but it does not heat everything evenly. Some objects heat up more easily than others, and some areas of the Earth receive more energy from the Sun. As warm air rises, cool air flows in to replace it.

The stronger the difference in temperature, the stronger the winds. Think of it this way: in the summer time, the temperature difference between northern Wisconsin and southern Florida is not that big. In the winter, however, that temperature difference can get quite large. In order for our atmosphere to remain in equilibrium, the winds must speed up. Wind is the Earth’s attempt to find a temperature balance.

Wind disperses more than just heat. When strong winds carry away soil, microbes in the soil can act like hitchhikers and go along for the ride. Nutrients and organisms lost from one region may be deposited across the globe. The organisms may colonize otherwise inaccessible regions. The nutrients being blown around the globe may help forested areas obtain trace amounts of minerals. Some organisms in particular get a significant amount of nutrients from dust on the wind. Lichens and epiphytes (“air plants”) are two examples.

Insects also use the wind for long-distance travel. Just how high can they fly? In the book Insectopedia, Hugh Raffles wrote that researchers calculated that “on any given day, the air column rising 50-15,000 feet above one square mile of Louisiana countryside contained an average of 25 million insects.” At the upper limit, 15,000 feet, there was a ballooning spider who used his silk as a kite. Butterflies, dragonflies, gnats, water striders, leaf bugs, booklice, and katydids have been sighted hundreds of miles out on the open ocean, and aphids have been found on ice floes. Some wingless insects (and plankton!) are plucked from their earthly tethers by a sharp gust of wind, but very few are completely passive travelers.

Wind also helps lakes balance their nutrients and chemicals throughout various layers during fall and spring turnover. During fall turnover, when the surface water cools to about the same temperature as the lower water, the wind can mix the water masses together and even out the temperature and oxygen levels. A similar process occurs during spring turnover after ice-out, as colder surface waters warm to the temperature of bottom waters and the lake mixes. Water from the lake bottom brings nutrients up with it.

While Nature’s howling winds have their purpose, I would still prefer a gentle breeze. Liu Chi, a scholar in the Yuan and the Ming Dynasties, wrote about the wind in a pine grove. “Listening to it can relieve anxiety and humiliation, wash away confusion and impurity, expand the spirit and lighten the heart, make one feel peaceful and contemplative, cause one to wander free and easy through the skies and travel along with the force of Creation.”

With every breath, we invite the universe in. As the winter winds swirl around you, take a peaceful and contemplative moment to appreciate the wind’s role in encouraging balance and unity in our sometimes stormy world.

Author’s Note: A version of this article was originally published in 2013.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum’s current exhibit “Anaamaagon: Under the Snow” is open through March 11. The Museum will be closed for construction March 12 through April 30. Our Winter Calendar is open for registration! Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Frost Cracks

Fresh snow highlighted every twig, and more flakes floated down as we hiked through the Rainbow Lakes Wilderness Area on the North Country Trail (NCT). This intrepid group of women calls themselves the NCT Navigators, and they meet almost every Monday (when the mosquitoes aren’t out) to hike a section of trail. Most of them have completed the NCT’s 100-mile challenge. Most of them are retired, too, and I count myself lucky to fit in a hike with them even a few times a year.

Today the fresh snow was making the ski trails slow, and I was looking for inspiration, so I gave my friends an assignment: find me something to write about! Well, this artistic group had already gotten in the habit of noticing patterns in nature, and it wasn’t long before someone keyed in on an adorably squiqqly line snaking up the length of a tree.

A frost crack! Of course. What a perfect topic for a winter day. Long ago I learned that these cracks burst open with a noise like a rifle shot as a sunny day plunges into a frigid night. I couldn’t remember, though: was it the contraction of cooling wood, or the expansion of ice that caused the trunk to split? Both make sense. I pondered this as we hiked along, and also tried to spot more cracks throughout the forest. It wasn’t hard. While not on every tree, I could see a long, vertical welt from just about any point on the trail. Quite a few of the cracks had their upper terminus at a scar where a branch had fallen off, or some other blemish on the tree.

Back at the office, I sought a more complete explanation. My initial research was frustrating, though, since the sources all gave multiple explanations of frost cracks. Yes, it seems to involve the low-angled winter sun shining heavily on the southwest side of a tree. The bark and inner wood both warm up and expand. When the sun sets and the temperature drops, the outer bark contracts more quickly than the inner wood, and suddenly becomes too small a sheath for its core. The bark and first layer of wood split.

Another part of the explanation is that the heat causes the tree’s cells to break dormancy. Dead cells, which compose most of the wood, just freeze, but trees winterize their living cells in a few ways. Cell membranes become more flexible, which allows water to migrate out of the cells and into the intercellular spaces where it can freeze without harm. Trees also fill their cells with sugar in order to lower the freezing point of their remaining liquid. And, like magic, the syrup inside the cells supercools to a glass-like phase where it is so viscous that it appears to be solid, while not forming sharp crystals. In a sun-warmed tree, water may begin to move into places it shouldn’t. As the tree re-freezes, water shifts around and freezes quickly and unevenly, causing stress on the wood and opening the crack.

A few sources mentioned that frost cracks are often associated with previous damage to the tree, but the process didn’t fully make sense until I read an interview with a plant pathologist in Northern Woodlands magazine. Walter Shortler and his mentor, Alex Shigo, did a sort of forensic pathology for trees. They used a chainsaw to slice up thousands of logs to get to the bottom—or the top—of the frost crack issue.

The result? Shigo found that “All radial shakes [cracks along the radius of the tree] were associated with wounds, branch stubs, or basal sprout stubs, and with ring shakes [cracks that follow tree rings] at some point in the trunk.” Almost anything can create an area of weakness: fire, damage during logging operations, poor pruning techniques by humans, gnawing rodents, rubbing deer, root rot, basal sprouts, or branch stubs that didn’t heal. Trees that are damaged when young seem to be much more prone to later frost cracking than older trees that become damaged.

In any case, damage to the bark and underlying sapwood provides an entry for decay. Bacteria and fungi move in, and as they decompose the wood it absorbs extra moisture. The defective wood doesn’t expand and contract as well as healthy wood, and rapid freezing finally bursts open a significant crack. Repeated freeze-thaw cycles, coupled with stress from wind, can enlarge a crack, even as the tree tries to heal it.

So, a combination of all the forces I read about likely play a role in opening and widening cracks, but none of them alone would do the job without a prior injury. This all made sense to me, especially in light of my observation that many frost cracks we saw topped out at an old branch scar.

The tree will try to heal the wound, and the growth of new wood around the crack is sometimes called a frost rib. Indeed, we admired the raised scar that highlighted our squiggly crack.

Foresters, of course, are concerned with reducing damage to young trees so that frost cracks can’t gain a foothold in what could have been valuable timber. Naturalists might appreciate a different perspective. A little ways down the trail we spotted another tree with a convoluted scar. Nestled inside were two brown acorns. I suspect that naturally occurring frost cracks may provide valuable habitat for critters in their cavities and decay. In the words of Leonard Cohen, “There is a crack in everything. That's how the light gets in.”

Author’s Note: This article was originally published in January 2018.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is open with our brand-new exhibit: “Anaamaagon: Under the Snow.” Our Winter Calendar is open for registration! Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.