Telltale Signs of Forests Aging - Naturally
Summer officially arrives tomorrow morning at 7:30. I argue the rumble of motorcycles last week already kicked off our fairest season.
Our “longest day” is summer solstice when the sun reaches its highest point in the sky over the northern hemisphere. In June, we experience the earliest sunrises and latest sunsets of the year. It’s the annual “high tide” in the forest, a brief verdant season of maximum growth.
We tend to imagine forests as unchanging in the span of our lifetimes. Many people prefer to think of trees as nearly immortal. Truth is: it’s often in the midst of summer that we first notice decline of a shade tree or thinning in the canopy where blue sky shows amid green leaves. One analogy is that male balding often starts in middle age. Some people are less comfortable with change in general.
Like people, trees have a genetic program that pre-determines their respective life spans. Sun-loving “pioneer” balsam firs, pin cherry and poplars live for only decades. Pines, oaks and white birches tend to live at least a century before entering a long, slow period of senescence and decline. The longest-lived deciduous trees are shade-tolerant beech, sugar maple and yellow birch able to live for 300 years while conifers red spruce and hemlock may live 400 years or longer! Lifestyle choices associated with being stationary and tall include risks from wind, fire, ice, lightning strikes and insects.
People are often just as alarmed to see signs of decline in favorite local trees as they are to note signs of aging in beloved relatives or even their own reflection in the mirror! Old trees develop thicker, craggy bark, analogous to smile lines, wrinkles and crow’s feet or age spots. An overall decline in vigor - even in middle age - often manifests as a thinning crown and decline of older, thick lower limbs. Trees decline for many decades beyond their economic maturity. From the saw-timber standpoint, they become “over-mature” or even “decadent” when past their prime.
Recently, I received several inquiries of concern about sick and dying oak and pine trees, potential discoveries of Asian long-horned beetles and about the status of pink lady slippers in our State’s forests. In each case, the question was framed from an assumption of “worst case scenario” Realities have proved a relief; even a re-leaf!
Tree boring longhorn beetles began hatching earlier than usual in May, invading homes and cars. Beetles collected by callers proved to be our native white pine spotted sawyer beetles rather than the dreaded Asian longhorn beetles not yet found here but discovered as nearby as Worchester, MA. Forest Health specialist Kyle Lombard at the NH Division of Forests and lands helped callers identify differences and had them mail their bugs to him (just in case). He said he’d gotten about 20 calls in one week from alarmed residents. Turns out the exotic tree-boring Asian beetles typically hatch later, in mid-July.
Concerns about dying red oak foliage along roads in particular hollows in the Monadnock Region were merely a result of late frosts during the middle weeks of May just as the tender leaves were unfurling. It was not what one inquirer feared was “sudden oak death” killing California oak trees.
Other recent news articles featured a link between premature browning and casting of white pine needles to a combination of the 2009wet summer and hot weather in April which jump-started a needle-killing fungus. The pines were not suddenly dying as feared. The premature needle cast is a weather- related phenomenon.
Both oaks and pines will recover
It can be human nature to assume “worst case scenario” rather than the simplest explanation. Perhaps media sensationalism of ecological disasters has created a default “Chicken Little” response?
We need to employ the philosophical premise of William Occam’s “razor” where the simpler of two or more competing theories for any phenomenon is a preferable explanation and should always be proposed first.
Public concern may even spawn enduring myths.
Consider the pink lady slipper orchid also called “moccasin flower.” People are quick to tell me that all lady slippers are extremely rare and protected by law. Well-meaning residents call to report the location of lady slippers they’ve discovered in their neighbor’s woodlot. Yellow lady slipper, Showy lady slipper and Dragon’s Tongue lady slipper are indeed rare, State-ranked, protected plant. But pink lady slippers are common. It’s a species of special concern because people may try to transplant and propagate them. They’re difficult to cultivate and require a special root fungus association to thrive. Lady slippers prefer partial sunlight. Populations often expand following partial cutting of a closed canopy forest. Thus, forest management isn’t antithetical to lady slippers but the myth of “rare and protected” persists.
Naturalist Dave Anderson is Director of Education and Volunteer Services for The Society for the Protection of New Hampshire Forests. His column appears once a month in the New Hampshire Sunday News. E-mail him at danderson@forestsociety.org or through the Forest Society Web site: forestsociety.org.