There is nothing quite like a tranquil walk through the forest on a crisp autumn day, but do not be fooled by this seemingly peaceful landscape; the forest and it's inhabitants are busy readying themselves for the harsh winter to come. Squirrels and resident birds are feverishly stashing cones and seeds, flocks or migrants are flying over head towards their distant wintering grounds and even the trees, behind their towering silence, are diligently preparing themselves for their winter slumber.
The beautiful greens that served the trees so well over the summer months capturing light to produce nourishing sugars and release oxygen, are slowly being degraded as day length shortens and temperature drops, revealing other hidden pigments. Carotenes and xanthophylls replace the dying chlorophyll with brilliant bursts of oranges and yellows. Anthocyanins preciously stored away in the vacuoles of the lead cells can finally display their fiery reds.
While the leaves are busy putting on a flamboyant show, the tree is slowly producing a layer of celles at the base of the leaf petiole. Once the layer is complete, the leaf will dance upon the wind for a moment before returning to the ground from which it came, leaving as only proof, a slight scar upon the branch from which it grew.
The tree had no other choice than to release its beautiful fall foliage as the hardship of northern winters do not allow them to keep such delicate structures. The snow would weigh down on the leaves until they are torn off or the branches collapse under their combined weight. Instead, the tree has stored energy in small buds that shall open up to full green splendour when the warm temperatures return. All broad-leaved trees in northern regions shed their leaves in fall. Some may keep their leaves longer, like the majestic oak whose brown leaves may persist well into the winter and even until next growth. In warmer climates, even broad-leaved trees can be evergreen, as they do not suffer from such cruel seasonal changes.
A dedicated observer will have no doubt noticed that not all trees shed their green leaves and that time has shaped these photosynthetic structures into resistant needles that persist throughout the winter: they are evergreens, conifer trees. Their strategy is different; by keeping their leaves, they can profit from the sun's bountiful presence for a longer period of time before the bitter cold stops photosynthetic activity.
When all that is left are naked branches stretching out as if to tickle the clouds, urging them to release their snowy blanket, the seasoned walker smiles knowingly amongst the silent trees and chirping chickadees; this is not the end, this is but an interlude of rest before the frenzy of spring. Soon this barren brown land shall turn a sparkling white and a whole new world will be waiting to be explored.
Written about a typical autumn day in Montreal, an attempt at lyrical science, posted out of nostalgia.