Natural Connections: The trees of the forest
By Emily Stone
Naturalist/Education Director at the Cable Natural History Museum
I don’t know about you, but this warm weather makes me wish for wildflowers! I hiked on the Forest Lodge Nature Trail yesterday, and sunshine had uncovered just a few patches of pine needles among the slushy snowdrifts. One patch contained the evergreen, oval leaves of trailing arbutus—with its flowers still over a month away. While we wait for the flowers, the trees are still here for our enjoyment. This week, I bring you information on several of our most common trees from the new interpretive booklet for the Forest Lodge Nature Trail.
Popple for Wildlife
Some folks lump all trees in the genus Populus into one category that they call “popple.” This group includes bigtooth aspen, quaking aspen, balsam poplar, and cottonwood. Popple trees can be hard to tell apart, and they all have seeds that float through the air on fluffy “cotton.”
Look up! The tall trees behind the marker are bigtooth aspen. Their spade-shaped leaves have large “teeth” on the margins. The leaves of quaking aspens are smaller, with finer teeth. Their long, flat stems tremble in the slightest breeze. As you walk the trail, watch for them quaking or shimmering in the wind. Both bigtooth and quaking aspen have pale bark on their twigs, upper branches, and young trunks. Old aspen trees will have brown, furrowed bark on their lower trunks. In contrast, birch trees have dark brown or purple twigs, but they have pale bark on their branches and trunks.
Beavers eat the inner bark, twigs and leaves of aspen trees. Deer, moose, and elk browse on the leaves and twigs. Ruffed grouse feed on the buds and the flower catkins. Many summer songbirds feed on insects found in the tree’s canopy.
How many more aspen trees can you spot along the trail? They are especially visible surrounding the parking lot at the trailhead.
At this stop you’ll find three common evergreen trees: balsam fir, eastern hemlock, and black spruce. Each of these trees has short needles that attach individually along the twigs. They look very similar, until you know the tricks to identification.
First, the polite thing to do when meeting a new species is to shake their hand. Seriously! If you grasp a twig of spruce needles, they will poke your palm. If you grasp fir or hemlock, their needles feel softer.
Next, pick off an individual needle. Can you roll it between your fingers? Spruce needles are square in cross section, so they will roll. Fir and hemlock are flat, and they resist rolling.
Finally, turn over the needles. Firs and hemlocks both have pale stripes on the underside of their needles. Hemlock needles are shorter that fir needles, and also have a tiny stem at one end.
You can also look at the bark. Spruce trees have scaly bark for their whole lives. Hemlock trees have flaky bark that turns to thick ridges as they age. Fir trees of all ages have relatively smooth bark interrupted by resin blisters.
Here are two sayings to help you remember:
“Spruce are spinny and spiney.”
“Firs are flat and friendly, with racing stripes like a fir-rari!”
Northern Red Oak
Towering above you is a northern red oak. It is the most common type of oak in the Northwoods. This tree is known for its acorns and shiny leaves with pointed lobes. White oak and bur oak leaves have rounded lobes. Red oak bark has flat, parallel ridges that kind of look like ski tracks.
Acorns are an important food source for chipmunks, squirrels, mice, deer, black bears, ruffed grouse, turkeys, and blue jays. Native Americans soak acorns in several changes of cold water to remove the bitter tasting tannin, and then grind them into flour. Oaks don’t produce a good crop of acorns every year, though.
As mast trees, oaks save up their energy for three to five years before producing thousands of acorns all at once. All the trees in an area will mast in the same year, and with so many acorns available at once, the critters cannot possibly eat them all. Some, at least, will survive to grow a new tree.
How do the trees know when to mast? Some scientists theorize that the networks of mycorrhizal fungi that connect a forest by the roots may help the trees share resources and information so that they can all produce acorns in the same year. All flourishing is mutual.
I hope you can get outside soon and enjoy some of the trees in your own backyard.
Editor’s note: Emily’s second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.