Forest Journal ~ Summer Sunlight Fades...Already
Summer Sunlight Fades...Already
By Dave Anderson
“Rage, rage against the dying of the light”
- Dylan Thomas
Summer Solstice in June was the annual high water mark for the flood of sunlight into dark northern forests. By late July, twilight falls earlier each evening. Yet compared to short dark winter days when the sun sets by four o’clock, these sweet, midsummer’s evenings of fireflies and Red Sox games at the end of long hot days still feature 25% more daylight than a typical winter day.
Sunlight is the “coin of the realm” in the forest and the current fifteen hours of daylight from 5:30 to 8:30 is the jackpot! Like the extreme tidal ranges of the north Atlantic coast of Newfoundland, our northern forests experience a brief summer floodtide of sunlight when even dour, old woodsmen dance, slap at their thighs and wave their arms about their heads with joy… or perhaps that’s just the deerflies?
The trees have just grown at their fastest annual rate and dense shade on the forest floor is a testament to the fierce competition in the canopy overhead to capture the sunlight. Early summer is when young leaves harnessed long hours of light to form sugars that fuel growth. Excess sugary summer carbohydrates are converted to starches to be stored in tree roots for next winter just like potatoes which keep in a root cellar better than sweet strawberries or blueberries. By now, the maple sugar crop for next March has already been produced in the summer leaves of sugar maples!
Do you recall the parable of the ant and grasshopper? A hard-working ant gathers food all summer to survive a coming winter while the lazy grasshopper enjoys the fine summer weather, playing his fiddle rather than work. I’m reminded of the tale each year when someone first reminds me “the days are getting shorter now and winter’s coming” and then adds: “Got your wood split and stacked?”
Ouch. That first winter reference stings. I’d rather see swamp maples redden in August before thinking about winter again. Truth is, most country-folk have long-ago cut, split and stacked next winter’s cordwood. The reliable, industrious ants disdain grasshopper tendencies to fiddle away the summer.
So it’s out to my woodpile where I’d rather study the logs than swing the heavy splitting maul in the humid summer air. Fiddling again.
See those annual growth rings at the cut end of each log? The lighter part of a ring is “spring wood” comprised of tiny tubes formed just inside the bark, microscopic drinking straws which conduct water from the soil up to the leaves. The darker line of a ring is “summer wood” comprised of smaller tubes formed when growth slows. Sorry to be a summer buzz-kill, but the earliest sign of autumn is now when daylight fades and plant growth slows.
Trees may lose twigs, branches and an occasional large limb as they age. Old age reduces vigor in trees just as surely as it does in humans. I describe older trees as senior citizens with patterns of hairline recession, gray hair and balding. Old age is also reflected in the craggy character of bark. Plates of progressively more shaggy bark characterize the older trees as their growth slows each decade. An old red maple looks more like a shagbark hickory and a yellow birch bark can look more like a black cherry at 200 years of age. Shaggy bark plates are the crow’s feet and wrinkles on the older faces of the forest.
Young trees are characterized by firm, tight bark as they grow fast in fierce competition for available sunlight. The short, northern growing season means sunlight is a “limiting factor” to growth, assuming ample water and soil nutrients are available. Large trees in the canopy have won their race to capture the light. Smaller trees languishing in dense shade await their chance in the spotlight - like second-string ball players “riding the pine” while sitting the bench.
Leaves rustle as fierce thunderstorms threaten and hurricanes brew in the tropics. Like the proverbial ant, our northern forests are well-provisioned for next winter by mid-summer. When the days first grow perceptibly shorter and nights longer in August, trees have already formed buds for next spring at base of each leaf stem. A waxy coat protects tiny summer buds from drying-out. Summer-formed buds are also an insurance policy in case of insect attack. If a caterpillar infestation were to defoliate trees, they can re-leaf using summer buds to make enough food grow a new set of buds to successfully over-winter. However, then annual growth is negligible. The weaker trees in the shade of the forest experience die-back as a result of defoliations by insects and stress from weather or atmospheric pollution. The annual growth rings formed during the last statewide gypsy moth infestation in 1981 are nearly invisible in the red oak logs of my woodpile.
Summer is so short, so make like a tree and soak up the sun while it lasts. Splitting wood and other chores can wait. Find your “inner grasshopper” and don’t be such an ant... now where’s that fiddle?
Naturalist Dave Anderson is Director of Education for the Society for the Protection of New Hampshire Forests. He can be reached through the Forest Society website at www.forestsociety.org.
Forest Journal appears in the Lifestyles section of the New Hampshire Sunday News and online at NH.com