Balsam Poplar: Tree of the Far North

We were supposed to be focused on birds as the group walked along the gravel road north of Grandview, but in the damp air I smelled something. Thick, sweet, and spicy, the scent hung in this one spot where tall trees gathered instead of the scrubby alder brush. I inhaled deeply, filling my lungs with an aroma that reminded me of lovingly cooked food, or carefully chosen perfume, or new life. I couldn’t quite place it.

Looking around the small patch of forest, I noticed olive-green bark near the top and gray-brown furrows at the bottom. Aspen, I thought. But wait. On a hunch, I jumped a wet spot in the ditch to get a better look at some lithe young twigs sprouting out of an injury in the base of one of the trees. The buds were almost an inch long and encased in shiny brown scales just beginning to expand. I pinched one, and the aroma intensified. Another birder walking near me looked curious, so I broke off the bud and handed it to her. “Hmmm…Oh!” she exclaimed as she caught the scent, too.

The buds of a balsam poplar tree are coated in sticky, aromatic resin that contains medicine for both the trees and us. Photo by Emily Stone.

The buds of balsam poplar were releasing their magic.

In Wisconsin, Populus balsamifera aren’t as common as their cousins the quaking and big-tooth aspens. Their numbers increase as you head north, and their groves catch my eye with a distinctive golden cast to leaves and bark whenever I head up Scenic Highway 61 along the North Shore of Lake Superior. Reaching peak performance on the damp soil and extreme cold of Alaskan and Canadian floodplains, balsam poplars survive the farthest north of any American broadleaf tree.

Similar to a big-tooth aspen, balsam poplars have pale young bark and furrowed older bark. The leaves, though, have finely serrated teeth and rusty blotches on the undersides. Their winter buds, as we noticed, are reddish brown, up to an inch long, and glossy.

As spring sunshine coaxes open the buds, that gloss becomes airborne. According to scientist Diana Beresford-Kroeger (“The Jane Goodall of trees,”) those aerosols act like “a health shield for all life on the planet.” The aromas wafting in the breeze contain a myriad of chemicals. They are anti-inflammatory, anti-bacterial, and anti-fungal. Often included in wild-crafted soaps and salves, balsam poplars have earned the nickname “Balm of Gilead,” after a rare, medicinal perfume mentioned in the Hebrew Bible.

The more scientists dig into the chemistry of balsam poplar, the more impressive it gets. In the poplar’s pharmacopeia, scientists have identified vasodilators that are important for heart health, and oxytocins that reduce blood pressure. These trees of the far north manufacture the molecular building blocks of the brown fat that humans use to shiver and stay warm. Tree bodies contain the same chemicals that the human body deems essential for brain, liver, and glandular development.

For years the Cree Nations have used balsam poplar sap to treat diabetes, and now scientists are expanding on that traditional knowledge. An article in the international, peer-reviewed journal of Evidence-Based Complementary and Alternative Medicine states “The results clearly demonstrated that the plant extract substantially attenuated weight gain and the development of insulin resistance [in mice].”

In fact, balsam poplars, who belong to the Willow Family, Salicaceae, have seemingly figured out the key to eternal life. Roots, stumps, and even stems and branches buried during autumn logging can sprout into whole new trees. Even 15-year-old cuttings regularly sprout new roots and shoots when planted in damp soil. Each spring, balsam poplar produces thousands of tiny seeds attached to silky parachutes—they are often called cottonwood like their southern cousins—but they mainly rely on vegetative reproduction, not those seeds.

So where do these trees get their super powers? Unlike the northern conifers, balsam poplars have taproots that dive deep into the soil, right down to the nutrient-rich permafrost layer (wherever there is one). The tree draws up minerals, concentrates them into the waxy green leaves, and generously drops them onto the ground every fall. This enriches the topsoil for all the neighbors. Beresford-Kroeger suspects that these habits, and their pharmacopeia, are all adaptations to surviving the harsh environment of the cold, dry North.

Somewhat ironically, this cold-adapted tree may win bigtime as the climate changes…at least for a while. As summers warm and lengthen, balsam poplars are intruding on formerly treeless areas at the northern end of their range. They are making fundamental changes in the tundra. In a journal article from 2016, Carl A. Roland (the botanist I studied with in Denali when I visited Alaska!) and his colleagues from the National Park Service declared, “It appears that poplar may thus act as the ‘leading edge’ of landscape change in this region…leaving a substantially altered, boreal landscape in its wake.” Meanwhile, they will disappear from the southern end of their range—like the gravel road near Grandview, Wisconsin.

That’s a lot to take in on a damp spring day.

Emily’s third book, Natural Connections3: A Web Endlessly Woven, 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. Our Summer Calendar is open for registration! The Museum’s new exhibit, The Wetland Way is now open! Discover how life thrives at the intersection of soil and water, and why we must care for these special places as they care for us. Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

A Prairie-Dweller Moves North

The birds were quiet, but a tangle of dead trees squeaked and chirped in damp gusts as we hiked back from High Falls in Tettegouche State Park, Minn. The falls had been gushing, and climbing the stairs near the falls had kept us warm, but now squalls of sleet were chasing us home.

A lump of gray fur in the middle of the trail pulled us up short. The small mammal was about the size of a gray squirrel, but with cute, round ears tucked below their silhouette instead of perked up tall. Like a thirteen-lined ground squirrel, they crouched close to the ground with their tail out long, but with none of the stripes. Head and tail were gray, but the fur on their midsection was a warm brown that matched the dry grass along the trail.

I’d never seen a Franklin’s ground squirrel before, but the previous morning someone posted two images of one to the Ely Field Naturalists listserv, and a lively conversation began about how pesky they can be in lawns and gardens around Ely, Minn., when they nibble on the stems of garden plants. “Aren’t they rare?” I wondered to myself, thinking about a beautifully restored oak savanna near Springbrook, Wis., where the presence of this small mammal is a point of pride for the conservation-minded landowner.

Whether rare or common, Franklin’s ground squirrels have a reputation for being hard to spot—by some accounts they spend up to 90% of their lives underground, either hiding safely in the summer, or hibernating with friends in the winter. The one we saw nibbled on new shoots among the dried grasses beside the trail before vanishing into the brush that had grown up in a patch of forest hit hard by windstorms. We had to skirt a freshly fallen balsam fir while stepping over the dried trunks of past casualties.

On various websites I read that Franklin’s ground squirrels are a species of tallgrass prairies, although they’ve declined as the prairies have declined. In the southeastern part of their range the squirrels are barely hanging on in grassy roadsides and railroad right-of-ways—the same places where a few native plants have escaped the plow. They are rare enough to be listed for special protection in Indiana, Illinois, Missouri, and Wisconsin. And several sources suggested that they belong only in the southern and western portions of Minnesota, in the prairie biome.

So what was this little prairie dweller doing in Northeastern Minnesota?

An article that J.J. Huebschman wrote for the Illinois Natural History Survey Bulletin in 2007 provided some clues. When Huebschman looked through a huge number of historic and recent observations, he found that Franklin’s ground squirrels are “most frequently associated with habitat characterized by a mixture of grassy and woody vegetation, referred to as savanna-like or parkland habitat.” It seems that they like the edges of grasslands—not the wide-open landscape that the word “prairie” typically brings to mind.

I decided to upload my observation to the iNaturalist website, and while I was there, I perused the map of all Franklin’s ground squirrel sightings. Zooming out, I saw a swath of red dots stretching from central Alberta down to the top of Wisconsin, with a couple outliers to the south near Omaha, Neb. and Springfield, Ill. Clusters around several population centers could be a result of more human observers rather than higher numbers of the observed species. But you never know—suburbanites also create edge habitat and grow tender vegetables which could help the ground squirrels survive.

Focusing in on Minnesota’s North Shore, I found quite a few sightings stretching along the lake from Duluth up to Grand Marais, and in a parallel band about 40 miles inland, angling all the way up to a Boundary Waters campsite on the Canadian border. Campsites must count as edge habitat! A circle of observations showed that these “rare” squirrels have been spotted at almost every site in the Baptism River Campground.

Humans have created a home for Franklin’s in other ways, too. The old forests of pine, cedar, and spruce that once darkened the North Shore would not have suited these grassland squirrels. But in the late 1800s, loggers took the big trees and left piles of slash. Huge wildfires with their intense heat destroyed much of what was left, and disrupted the normal processes of regeneration. In their wake, pioneering birch trees colonized the shore with native-but-weedy bluejoint grass beneath—especially between Highway 61 and Lake Superior. Both the thatch of grass and the influx of deer made it extremely hard for new conifers to grow up beneath the birches. Wind events (and human development) in recent decades have torn holes in once-dense forests, creating even more edge habitat.

The fur of Franklin’s ground squirrels looks gray due to alternating bands of black and white on individual hairs. Photo by Emily Stone.

A century ago, I would have been more likely to see a Franklin’s ground squirrel at my grandpa’s farm in southern Iowa. It seems that we were both chased north by the intensity of farming on the former prairies and the decline of wild spaces there. Even though the North Shore has experienced plenty of human impacts, I hope both the Franklin’s ground squirrels and I find it to be a good new home.

Report sightings to the Minnesota DNR here: https://www.dnr.state.mn.us/eco/mbs/sightings.html

And to the Wisconsin DNR here: https://survey123.arcgis.com/share/f57cba58511a4c99b1d1292776b05125

Emily’s third book, Natural Connections3: A Web Endlessly Woven, 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. Our Summer Calendar is open for registration! The Museum’s new exhibit, The Wetland Way is now open! Discover how life thrives at the intersection of soil and water, and why we must care for these special places as they care for us. Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

The Trill of a Pine Warbler

On a cool morning in mid-April, two friends and I ambled down a gravel road toward their family cabin. What we’d planned as a quick drive to scout for black ash trees to harvest for basketmaking had turned into a longer trek because of a maple tree whose rotten base had unexpectedly given way and blocked the road. A walk through the spring woods was no hardship, though, and we identified six trees to harvest during the first week in June!

Black ashes like to grow in vernal pools that are wet in the springtime. Photo by Emily Stone.

(If you’d be willing to help April Ogimaakwe Stone, member of the Bad River Band of Lake Superior Chippewa, harvest and pound the trees into basket strips during the first week of June, check the Cable Natural History Museum website for details!)

Past the cheerful red cabin and through the deep green of a pine grove the cold water of Lake Namakagon glimmered. I imagined that the lake was shimmying with the relief of being released from the grip of rigid ice. The local loons were back, but not many other birds had returned to the Northwoods yet. We’d spooked a couple of hermit thrushes earlier, but they just bobbed their rusty tails and vanished into the woods without giving us the pleasure of their flute-like song.

Then a musical trill sounded from the treetops. Pine warbler! These hardy birds spend the winter in the southeast third of the United States instead of flying all the way to Central or South America like many warblers. Some pine warblers live year-round in the Southeast, welcoming their northern counterparts into large winter flocks, then nesting once the competition clears out. And they sing all year, even in winter and even on migration. Back in early March when I participated in Loon Camp in South Carolina, our morning bird walks were filled with the trills of pine warblers. I felt like I was hearing the voice of an old friend.

With such a short migration, pine warblers can start moving north as soon as the weather permits. Their bright yellow feathers arrive right along with early spring sunshine.

The gravity of the lake and the sloping bank pulled us down until we were standing on the shore. My companion gasped in the middle of a sentence as a pine warbler darted over my head and landed on rough spruce bark a few feet way. Pine warbler males are known to be territorial for most of the year. They will fly at many different intruders, not just other pine warblers. Was he warning us to stay away?

He swooped to a rock wall and paused mid-hop to belt out a trill. It was easy to identify the source of this song as we watched his stout beak open and his white wing bars vibrate with the effort, but chipping sparrows and dark-eyed juncos are two other early returning birds who sound very similar. To my ear, the variation of the speed and tone of the trill within each species is just as large as the variation between the three species. Juncos and sparrows tend to sing from lower branches, bushes, and even while on the ground, but so did this pine warbler!

In general, if I hear a trill coming from high in a pine tree, or especially from a whole cluster of pine trees, my first guess is pine warbler. They are aptly named, as they are rarely spotted anywhere but in pine trees. Like nuthatches, they forage by hopping slowly along trunks and branches to find insects.

A few days later a flash of yellow interrupted the usual succession of chickadees and nuthatches visiting the bird feeder at my kitchen window. Insects are pine warblers’ main food source during the breeding season, but because they are adapted to eating pine nuts in the winter, they are far more likely than other warblers to visit your bird feeder. Just like ruffed grouse, their gizzards grow larger when they need to digest a higher proportion of tough seeds.

The round, yellow, bundle of energy on my feeder flew briefly out of sight, but immediately returned—or was that another pine warbler taking turns? The bird cocked their head as if they had some questions for me, too!

Unlike many birds, pine warbler numbers have been increasing in recent years as some pine trees recover from logging and expand into previously deciduous forests. For at least a century there have been plenty of evergreen trees near this house, but this is the first time I’ve seen pine warblers at my bird feeders, and I’ve never observed them nesting here. Perhaps with their increasing population they’ll have to expand into my yard. What a trill that would be!

Emily’s third book, Natural Connections3: A Web Endlessly Woven, 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. Our Summer Calendar is open for registration! The Museum is closed until May 12 to allow for construction of our new exhibit, The Wetland Way. Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.