NATURE NOTES: – From the backyard to the biosphere – When a Tree Falls in the Backyard:

NATURE NOTES: – From the backyard to the biosphere – When a Tree Falls in the Backyard:

What are we on now – our fifth hurricane of the season? Or is it the seventh? It’s hard to keep track; right now we seem to be hearing of a new severe storm each week. Sitting pretty in Southern Ontario, I hardly have to consider the gale-force winds and nasty weather that has so strongly affected others’ lives. Still, hearkening back to a week ago, when Isabel rather than Juan was occupying everyone’s minds, I recall that I was in reality touched by the storm, and was reminded, although very gently, of the potential force of those seemingly benign and delicate substances we call air and water.

It was the middle of the month, and I awoke to the sound of a loud crack, a crash, and a pounding heart. Leaping from bed and pulling back the curtains, I found myself gaping at the remains of what was once my grand little apple tree. Now so ungraciously positioned with bottom up and rustic swing poking unbecomingly from between its branches, the tree was a sorry sight indeed. What had once given my as yet aesthetically-lacking new yard a touch of country charm and a dose of much-needed beauty was now little more than a mass of twisted branches lying on a squashed fence. Or so I thought at the time…

But as we worked to saw and tug, sort and pile, I began to think of the tree’s falling as not just a loss of my favourite vegetation, but as an addition of an element to the ecological cycle of birth, death, decay, and regeneration – a lot of philosophical thoughts to be having while I mourned the passing of my yard’s most lovely attribute. But in the life of a tree, its demise really is as important as its upright existence. And though the ecological impact of my backyard apple tree’s end will likely be minimal compared to the effect that such an event would have in a forest, I began to think of my tree’s falling as representing a microcosm of what all windblown vegetation really is.

So what is the importance of a fallen tree? Well, there are two angles from which this question must be answered. The first is related to the tree’s absence: the opportunities its departure provides for other ecosystem elements. The second is related to what the tree itself, in its new form, provides for surrounding organisms.

When a tree falls, it does not just leave space, a void and useless hole in the forest canopy. On the contrary, its loss actually allows for the infusion of an all-important and oft-limited factor into the ecological equation: light. When strong gusts blow a tree to the ground, the whole forest floor, which was once blocked from the sun by the canopy above, is now drenched in sunlight. Feeble seedlings, grasses and even wildlflowers jump at the opportunity to grow as though life were a heavenly meadow; the plant diversity and productivity in forest gaps often far surpasses that of the typical shaded understory.

And what of the physical legacy of the tree itself? A fallen tree does not just disappear, but rather ends up in its entirety on the forest floor. It is still very much a tree, just in horizontal form, with branches askance and leaves strewn all about. While the utilitarian among us may see a freshly fallen log as a waste of usable wood resources, this huge mass of vegetation in fact acts as a very important and very significant soil fertiliser. And though its full decomposition takes years, a fallen tree provides for all that time a variety of resources for small forest critters, acting as home, shelter, food and protection for everything from insects to reptiles to mammals. The fallen tree can also act as what is known as a nurse log for the establishment of seeds raining down from the canopy above.

Have a look at a yellow birch next time you’re walking through the woods. These trees very often have high, arched stilt-like roots. Landing in the perfect growth medium of a rotting log, the seeds of the yellow birch will sprout, grow, and flourish as the log decays beneath it. The strange stilt-like legs of the birch are a testament to the tree’s first home in an old log that has now become fully assimilated into the forest floor.

And so I close with a nod of respect to Isabel and her family of hurricanes. As all good storms should, she acts as a reminder that in the seeming chaos of roaring winds and torrential rains, there lie some very important, very logical, and very ordered ecological necessities. A gap is as important as a tree in the life of a forest, and it is those gales and gusts that help that little patiently-waiting gap ecosystem to have its day in the sun. Dear Isabel, I miss my tree. But may my log pile and yard gap provide an opportunity for new life.

Zoe Dalton is a graduate of York University’s environmental science program, and is currently enjoying working towards a Master of Arts in Integrated Studies with Athabasca U. She can be reached for comments or questions at zk_dalton@hotmail.com.

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