It really was the springtime of my life in 1966 when Simon & Garfunkel released their song Hazy Shade of Winter. My personal interpretation of the lyrics has evolved over the years. But although Paul Simon wrote the song in England, the chorus continues to ring true to anyone who spends February in the Great Lakes region.
“Look around
Leaves are brown
And the sky
Is a hazy shade of winter”
When you venture into a mixed hardwood forest this winter, look around. The leaves are brown… especially the leaves on oak and beech trees. Young trees of these species tend to hold on to their leaves all winter, but even mature trees rattle with brown dry leaves, at least on the lower branches.
When deciduous trees fail to drop their leaves until spring, we call it marcescence. It’s an enzyme thing—and scientists have a pretty good idea how it happens. Why it happens is still a matter of speculation.
Some think it is nutrient cycling. If leaves fall in the spring, they add minerals to the soil just when the young trees need to be fertilized.
I lean toward the theory that the brown leaves protect the trees from hungry deer. Dead leaves are bitter, crunchy and they hide the tender buds. So deer don’t eat them, but instead browse on cedar and other deciduous trees, devouring everything they can reach. This creates a browse line, an obvious boundary between upper normal plant growth and lower stripped and eaten-back twigs.
Clearly, marcescence protects young trees from being browsed by deer. But on mature oaks and beech, brown leaves cling significantly above the browse line… often sixteen or seventeen feet above the ground.
Puzzling!... until I listened to a webinar about oak trees presented by Dr. Douglas Tallamy. He suggested that deer and even elk cannot reach that high, but that for several thousand years after the last Ice Age, megafauna---huge mammals—roamed the Great Lakes region. Perhaps the trees adapted to protect themselves from, say, woolly mammoths and giant sloths.
As winter progresses, the brown leaves on the beech trees will be bleached to silver, but oaks—look around....the leaves are brown, and on far too many days, the sky is a hazy shade of winter.
