Wed December 28, 2011
Earth Notes: Winter's Evergreens
When summer’s flashy circus of wildflowers has passed and the last browned autumn leaf has fallen, an eye looking for signs of plant life is left with the conifers, those stalwart trees that stay green all year long.
Conifers do drop their needles and replace them with new ones—just not all at once. Their ability to photosynthesize all year long gives them a built-in advantage in living in places with a relatively short warm season. So does their natural chemical antifreeze, which prevents needles from freezing even in frigid conditions.
But southwestern conifers are a diverse lot adapted to a wide array of conditions. The junipers and pinyon pines that surround many towns are adapted to heat and aridity. Like many conifers, they provide important food for wildlife—and for people, when it comes to the tasty and energy-rich seeds of pinyon pine that typically crop up in great abundance every seven years or so.
The firs and spruces of high places, on the other hand, are ideally suited to the extreme conditions of mountain winters. Their conical Christmas tree shape allows them to shed heavy loads of snow without damage to branches. Firs and spruces can also handle the often-shady conditions of cool canyons—or grow under a leafy canopy of faster-growing aspen trees.
How do you tell the difference? Fir needles are flat, while those of spruces are stouter and four-sided.
Whatever their type, evergreen conifers are a reminder that there’s still a lot of life happening out there—even in the cold.