Tilt and Whirl

Bees drone lazily in the late afternoon sunshine. A rainbow of flowers blooms along roads, in gardens, and on Hawaiian shirts. Some of the shyer birds have quieted down, while vireos and thrushes still sing their hearts out on their breeding territories. Loons have fluffy chicks riding on their backs. Fox kits play and sun themselves outside the den. Mosquitoes buzz in your ears, and shimmering dragonflies come to your rescue.

In this season of growth and vitality, it is easy to forget how stunning the fall colors can be, or how the yard looked covered in snowdrifts. Every season has pleasant and unpleasant aspects, and they are all made possible by the tilt of the Earth on its axis.

The Earth’s axis is an imaginary line going right through the planet between the north and south poles. The axis is tilted 23.5 degrees off the plane of the Earth's orbit around the Sun. For several months of the year, the half of the Earth that’s tipped toward the Sun receives more direct rays than the other half. We are now absorbing more energy from the Sun than we will at any other time of year. Plants sense it, and they grow furiously – photosynthesizing like crazy – before cool weather and lower sun angles bring on winter dormancy again.

Without the tilt of the Earth’s axis, our day length would not change, Alaska would have perpetual twilight, and we would not have the wonderful variety of the four seasons. Instead, two slightly different seasons might emerge based on the distance of the Earth from the Sun. Our elliptical orbit takes us farthest from the Sun (to a point known as the aphelion) around July 3. The perihelion, or the closest point in our orbit, happens around January 4. The difference between the two distances is about 3,000,000 miles, a variation of only about 3%. This causes a fairly minor change in the amount of energy from the Sun that reaches Earth, and would not lead to our rainbow of seasons by itself without the tilted axis.

Although the word solstice derives from a combination of Latin words meaning "Sun" + "to stand still," the Solstice is not constant over the years. The tilt of the Earth’s axis changes by 2.4 degrees (between 22.1 and 24.5 degrees) over 41,000 years. We are comfortably in the middle of that range right now. When the Earth tilts less, the Sun is lower on the horizon in the summer and higher in winter. Thus, summers are cooler while winters are warmer. This changing tilt is one of several large-scale factors influencing the advance and retreat of glaciers.

Glaciers shaped our landscape, while the seasons decorate it. Both owe some thanks to the tilt of the Earth on our axis. While the tilt of the Earth has a big impact on our lives, that tilt may have been caused by a large impact itself. One theory suggests that a huge chunk of space dirt in the early solar system may have slammed into the still-molten Earth – ejecting material that would become the moon.

No matter what you believe, I hope you enjoy these long summer days, and sweet summer nights.

Happy Solstice!

A little bit of good in every bad

The peas are planted, the beans are watered, tomatoes are towering, and the basil is in. Gardening season has begun in full force, which means that I am feeling happier and smarter than I have all winter. This is not just an anecdotal “I love gardening” testimonial – there is scientific research to back up my claim.

During those long hot hours I spend toiling in the dirt, my body is synthesizing vitamin D. This fat-soluble compound is linked to depression prevention, immune system strength, bone health, and more. I cannot quite do photosynthesis like my tomatoes, but at least I can make something useful from sunlight!

It is not just the sunshine that makes gardeners so happy this time of year; it is also the fresh air. We inhale an elixir of happiness from the soil. A common soil bacteria – Mycobacterium vaccae – has been shown to increase serotonin (a happy chemical in your brain) levels in mice. Not only does this decrease anxiety, but it also makes the mice smarter! 

Mice given the bacteria navigated a maze twice as fast as the control mice. The effects do not last long, though, and scientists surmise that humans would need to be exposed about once a week in order to reap the benefits of these healthy bacteria.

Unfortunately, gardening season coincides with another season as well. Everywhere that clean, fast-flowing streams laugh and tumble down rocky paths, tiny larvae cling to the submerged surfaces of rocks and logs. At the business end of the tiny, worm-like creature is a pair of foldable fans. These fans strain passing debris from the fast-flowing water and the larva scrapes a snack into its mouth every few seconds.

After seven to ten days of eating and growing, this little larva will pupate (like a butterfly spinning a chrysalis). The creature spends a week in the pupa, completely rearranging its body and developing the tools for a new way of life. Then, in bubble of air, an adult black fly rises to the surface.

If it is a male black fly, we can pretty much ignore it. Males eat a little nectar, fertilize a female in flight, and die. Females may also use the sugary liquid to fuel their flight, but making eggs requires a blood meal. This is where gardeners, paddlers, hikers, anglers, and other outdoor enthusiasts come in. The black fly female will slash a little cut in your skin, inject an anti-coagulant with her saliva, and drink her fill.  No matter that her “fill” is approximately 0.00006 ounces, the bite’s ill effects loom much larger. We end up with bleeding, itchy, swollen welts around wrists, beltlines, necklines, hairlines, and ankles.

Nothing in nature is all bad, though.  These tiny tormenters feed tasty trout, beautiful birds, dashing dragonflies, and swooping swallows. Folklore claims that black flies pollinate blueberry flowers and improve fruit-set, but the scientific jury is still out on that one.

In Maine, the Black Fly Breeder’s Association sells humorous t-shirts and donates the money to charity. One t-shirt design lauds black flies as “defenders of the wilderness,” due to their ability to keep timid tourists at bay.

Despite the good qualities of black flies, we would all probably prefer to avoid them. Happily, they do not sneak indoors like mosquitoes, but indoors is not where the vitamin D and happy soil bacteria live. Dark colored clothing, carbon dioxide, and perfumes all attract them. So it follows that if we would like to deter black flies, we should wear white, not exhale, and not wash our hair or use deodorant. As a side effect, many friends and colleagues will avoid us, too.

After five or six hot days, the tender little bodies of black flies (one sixth of an inch long!) dry out and black fly season will be over.

Later in the summer, as my tomatoes ripen and the pea pods swell, I will be able to enjoy the sunshine and soil bacteria in an enlightened state of peace and happiness…interrupted only by the painful bite of horseflies.

Little White Flowers

The bright colors of newly opened flowers carpet the road ditches, and this makes riding my bike a little more dangerous. I am risking skinned elbows and broken bones as I crane my neck to attempt ride-by plant identification, or swerve onto the soft shoulder to get a better look.  It is worth it to greet old friends.

Sometimes in February when the ski tracks on the Birkie Trails are just perfect, I wish it could always be ski season. Then spring arrives in all its glory. In any season, I love seeing a delicate white dusting in the ditches and forests. Of course, right now the white dusting is flower petals instead of snowflakes.

Three species with white flowers stand out in my mind this week. Starflower is one. They are aptly named, since their white petals reflect light so brightly that they seem to glow from within, and overexpose any photo I take of them. This low plant has a whorl of lanceolate (long, narrow, but wider in the middle) leaves with many delicate veins. Up to three flowers seem to float above the whorl on slender pedicels. What makes this flower truly unusual is the number of petals. Sets of seven are very rare in nature!

Often growing nearby in the sun-dappled edges of northern woods are Canada Mayflowers, sometimes called False Lily of the Valley. A shady patch of their small oval leaves may bear no flowers at all. Sometimes just a few plants in a patch will grow a taller stem with two or three leaves and a spike of snowflake-like white flowers. The single leaves may help provide a “chosen plant” with the added energy it needs to bloom and set seed. Since the plants in a patch are clones connected by underground stems, all the little sugar factories can work together. As all hardy northern residents know, teamwork is necessary in the face of poor soil and short summers!

The third white flower that caught my eye has a couple tricks up its leaves, or rather, in the flowers themselves. Bunchberry is the smallest plant in the Dogwood family. With radiant white flowers in the summer and brilliant red bunches of berries in the fall, this common plant is always a treat to see. And it is more than meets the eye! The four white things masquerading as petals are actually sepals. We usually find sepals as the small green leaves cupping a flower. While the sepals of bunchberry flowers are unusually showy, the petals are unusually dinky.

Small though they may be, the cluster of tiny flowers bears petals designed like a catapult. When the flowers are ready, the lightest touch of a potential pollinator’s foot will trigger the petals to burst open in less than a millisecond.  This triggers the stamens to shoot up and fling pollen grains with the force of a huge explosive.

According to J. Edwards, et al, the authors of the original study published in the journal Nature:

  

“Bunchberry stamens are designed like miniature medieval trebuchets — specialized catapults that maximize throwing distance by having the payload (pollen in the anther) attached to the throwing arm (filament) by a hinge or flexible strap (thin vascular strand connecting the anther to the filament tip). This floral trebuchet enables stamens to propel pollen upwards faster than would a simple catapult. After the petals open, the bent filaments unfold, releasing elastic energy. The tip of the filament follows an arc, but the rotation of the anther about the filament tip allows it to accelerate pollen upwards to its maximum vertical speed, and the pollen is released only as it starts to accelerate horizontally.”

The pollen experiences 800 times the acceleration that the Space Shuttle does during liftoff, and is launched more than ten times the height of the flower.  From this lofty height of 2.5 cm, they can be more easily carried by the wind. Or the soaring pollen might smack into a bee and travel to a different flower that way. Bunchberries cannot self-pollinate, so this cross-pollination is necessary.

Flowers like these are worth a little swerving as I ride down the road. Those who are risk averse may choose to walk instead. In either case, drivers should be alert and give a wide berth to the many bikers and walkers out enjoying the wildflower gallery along our roadsides.

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/

Little Solar Panels

As the days get longer and the trees leaf out, spring ephemeral wildflowers race to soak in as much sunshine as possible. Spring beauties, wild leeks (ramps), Dutchman’s breeches, wood anemone, bloodroot, and trout lily are some of the most beautiful treasures of spring. They rush out of the ground each year, sometimes while snow still haunts the north-facing slopes. Flowers bloom, leaves unfurl, bees hum, ants crawl, seeds are set, photosynthesis produces sugars, starch is stored back into the roots, and then—just as the tree leaves above are reaching their full potential—the ephemeral leaves melt back into the duff.

Spring ephemeral wildflowers have figured out that they can make use of the rich soil in shady depths of deciduous forests, so long as they get a head start on the trees. Partly because they only show up for such a short time each spring, they have captured many a heart. They also capture many a photon.

Photons are little packets of energy that travel through space.  We know them as light. They carry energy from the Sun (released during nuclear fusion reactions) down to Earth. Once here, they provide almost all the energy for life on Earth. Plants, like these lovely spring ephemerals, are an essential link between the Sun and animals, since animals cannot capture sunlight on their own.

For just a few short weeks in spring, the flowers I mentioned above are absorbing photons like crazy, and using them to help split carbon dioxide from the air and water from the soil, and recombine those molecules into sugar.  Sugar is simply carbon, hydrogen, and oxygen.

This month, I am exploring the process of photosynthesis with first graders who come to the Museum for field trips. We act out a food chain starting with the Sun, and then shrink down so we can be magically transported into a leaf.  There we meet Chef Chlorophyll, the green pigment that mixes the ingredients of photosynthesis. The students race around the yard, gathering sunlight (yellow water), water (blue water), and air (drinking straws) to create a frothy green soup in the mixing bowl. Then we each eat a grape, and consider how plants produce the sugars that we eat every day in a hundred different forms.

The sugars produced by spring ephemerals are not distributed in sweet fruits, though. These plants mostly produce hard, dry seeds without the juicy cradle of flesh like apples and cherries. Instead, their precious sugars are stored as carbohydrates (complex sugars) in starchy roots. Burrow your finger into the soft soil near any of these plants, and you will soon pull out a small white tuber. The tubers of trout lilies and spring beauties have a mildly sweet flavor. Leek tubers store their sugar with an oniony kick. Dutchman’s breeches and bloodroots store their sugar with toxins added.

The spring ephemerals used the energy stored in these tubers to get a head start on the tree leaves this spring, and they are rushing to replenish their pantry for yet another year.

All summer long, other plants will be capturing the energy from photons of sunlight and storing it in their roots, stems, leaves, flowers, fruits and seeds. We harness that energy in a myriad of ways. Think about that as you eat you dinner salad, turn on the television, plant your garden, drive your car, and drink your morning coffee! Energy from the Sun is integral to every aspect of our lives. 

Murmuring Trees

“Trees, trees, murmuring trees!” Through closed windows on a chilly morning I hear the welcome song of an old friend. It is followed by an emphatic chant from deeper in the forest. “Teacher. Teacher! TEACHER. TEACHER!” And then a buzzy, upward-trending “Parrrrrrrrula.” I catch a flash of movement out of the corner of my eye, and then hear the squeaky "wee-see-wee-see-wee-see" of yet another neighbor.

The warblers are back! Warblers are a group of active little birds that are often colorful, insectivorous, and (as their name suggests) vocal. They spend the winter in exotic locales to the south, and travel thousands of miles on their tiny wings just to raise their young in the Northwoods. You may be wondering what attracts them all the way up here from sunny Mexico and Costa Rica. Are you reading this on your deck? Then the answer may be sucking your blood or buzzing in your ear at this very moment.

Blackflies. Mosquitoes. The warblers come here for the feast. Moths, wasps, bees, caterpillars, larvae of all kinds, leaf beetles, bark beetles, weevils, ants, aphids (and their honeydew), caddisflies, craneflies, mayflies, stoneflies, dragonflies, grasshoppers, locusts, and gnats. During outbreaks of pests like the spruce budworm, warblers become rainbow-colored exterminators.

Could we please have a resounding “Thank You!” for the warblers?  Let us put them on a pedestal with spiders and bats and thank them all for eating insects.

Not only do warblers eat insects, but they look and sound delightful while doing it. For those of you who are curious, the bird songs mentioned at the beginning belong to, in order, Black-throated Green Warblers, Ovenbirds, Northern Parulas, and Black-and-white Warblers.

If you would like to learn more, there are plenty of opportunities every spring at the Chequamegon Bay Birding and Nature Festival. There are over 100 activities and field trips planned for birders and nature lovers of all skills and ages. Check out the field trips and register at http://www.birdandnaturefest.com/.

Slugs

Have you ever really looked at a slug? Not many people have, I would guess, except for gardeners who pluck them off ripe tomatoes. I first began to appreciate them after watching a French documentary called Microcosmos. It is a stunning film that captures a day in the life of a meadow – from a bug’s eye view. The crowning scene, for me, is a romantic encounter between two snails. Their antennae touch tentatively, then caress enthusiastically. It is all undulating, glistening slime on a bed of vibrant moss as they slowly topple over in ecstasy. Whew! A bit steamy, even for invertebrates. Snails, of course, are relatives of slugs. Slugs are basically snails that have adapted to living in areas without much calcium from which to make a shell.

Just the other morning I found some slugs on my driveway doing very important work. There were about ten of them, each bright gold body just over an inch long. They were gliding hungrily over a giant pile of bear scat. Slugs are decomposers – unsung heroes of nature. Unless you are an avid gardener with an active compost pile, you probably do not think about decomposers often. They work in the dark, dank depths of the world, neatly breaking down organic material into the ingredients for new life. Each beautiful wildflower, every fresh tomato, is made possible by behind-the-scenes decomposers.

At science camp, we called this team the “F.F.B.I.,” which stands for fire, fungus, bacteria, and invertebrates.

Some plants have very specific partners – like the trailing arbutus I mentioned last week, with its mycorrhizal relationship with fungus on its roots. Jack pine is a classic example of a plant that likes to collaborate with fire, since the resinous cones and tiny seeds of the tree need heat to open, bare soil to germinate, and a ready supply of nutrients from the ash. Ants are an invaluable invertebrate both to peonies, who need ants to chew open their buds, and to trilliums, who need ants to plant their seeds.

Human tinkering can disrupt these partnerships. Earthworms can increase nitrogen in the soil, but while that is good for your tomatoes, it can be bad for native plants. Earthworms are not native in lands like Northern Wisconsin, where glaciers still froze the ground solid just 10,000 years ago. Escapees from gardens and bait buckets invade forests. Maple seedlings and wildflowers actually need the fallen leaves for seed germination, and these European earthworms are too efficient at their vocation of decomposing the leaves.

The connectedness of nature became apparent when researchers discovered that earthworms are to blame for the population decline in ovenbirds, a ground-nesting warbler. Less leaf-litter means fewer insects for the ovenbirds to eat. Taller flowers and ferns that thrive in thick leaf litter are thinning out and being replaced by grasses and sedges that do not provide good nesting cover.

Like all things in nature, balance is necessary for a health. Worms are helpful in some ecosystems, but worms in the wrong place upset the balance. Too much fire will sterilize the soil; too many insects may decimate a tree. Wintergreen in the road ditch has beneficial fungus on its roots, and a powdery white pathogenic fungus on its leaves. Consider our own bodies where there are multitudes of helpful bacteria and a few that can cause serious harm. In trying to manage the harmful ones, we do not want to eliminate everything.

So as you admire the conspicuous beauty this spring, remember to appreciate the web of support that keeps it going. We all need “decomposers” in our lives – those partners who help us to nourish our souls, break down barriers, clean away debris, turn failure into beauty, and cycle with joy through many seasons of growth and renewal.

Think about that the next time you see a slug!

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opens in May 2012. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/

Conspicuous Beauty

“Conspicuous beauty” surrounds us in this stage of spring. A soft green haze covers the tamarack swamps as their delicate needles emerge. The cries of loons finding mates and defending territories echo over glassy lakes. More subtle songs fill the forest every day as warblers migrate through or set up territories. New flowers peek out from every habitat and patch of sun.

Two of the wildflowers blooming now hold special places in my heart, with two very different styles. The white clouds of blossoms on serviceberry shrubs are the most spectacular. This member of the Rose family blooms synchronously, with 90% of the flowers of a tree opening within two to five days. As legend tells, this lovely bush earned its name because it blooms when the ground has thawed enough so funeral services can be held for unfortunate souls who died over the winter when the ground was too hard to dig.

The synchronous bloom also creates a bonanza for the small bees that pollinate it. Even though the nights are still chilly, bees can shiver to warm up their flight muscles, and their fuzzy coat helps to insulate them against frosty temperatures.

I first discovered serviceberry in a botany class. We only learned to identify it to genus – Amelanchier – because the species are notoriously hard to tell apart.  Of the twenty species in the genus, nine of them live in Wisconsin! I never learned it as a kid, because I grew up in the limestone bluffs of the Driftless Area, and serviceberry is not tolerant of calcium carbonate. It prefers higher acid soils like the sandy glacial outwash and igneous bedrock of this region.

Trailing arbutus, another favorite flower of mine, also likes acid soils and has white, five-petaled flowers. Its scientific name, Epigaea repens, which means “trailing upon the Earth” describes its growth habit perfectly. Although the trumpet-shaped flowers look and smell wonderful, it can be hard to find them among the thick mat of broad, oval, leathery evergreen leaves. Without a trained eye, it may be mistaken for wintergreen, a close cousin.

I first discovered trailing arbutus on a portage trail in the Boundary Waters during an early spring canoe trip. It cheered me up immensely after a few days of traveling in wet snow and high winds.  I am not the first to appreciate its early spring beauty – as legend tells, it was the first flower to cheer the hearts of the Pilgrim Fathers after the rigors of their first New England winter. This earned it the alternate common name of Plymouth Mayflower, and the honor of being the Massachusetts State Flower. One author described it as having “the fatal gift of conspicuous beauty” that led to it being dug up and sold in eastern cities in the 1900s.

While many people love it, and have tried to transplant it into gardens, trailing arbutus does not fare well with disturbance.  Like orchids and blueberries, trailing arbutus has a mycorrhizal relationship with fungus on its roots. The plant has almost no root-hairs, which in other species are key for increasing the surface area available to absorb water and nutrients from the soil. Fungal hyphae (fine root-like parts of a fungus) surround and penetrate root cells, which allows for an exchange of water and nutrients from the fungus, and sugars from photosynthesis in the plant. A study in the Harvard Research Forest found that 91% of plant species there had similar fungal friendships!

Spring is a wonderful time to enjoy both the conspicuous and the inconspicuous beauty of nature’s awakening.

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opens in May 2012. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/