Through an Ecologist’s Eyes

So often when we think of climate change, the magnificent images of an ice sheet calving or a polar bear adrift dominate our thoughts, but as I hiked up Death Canyon in the Tetons with a dear friend of mine, she began to play out a story far more intricate and complex than the charismatic stories that dominate the news.

I first heard of Clark’s Nutcrackers in an Animal Behavior class in college. They are master cachers who have evolved a mutualistic relationship with the whitebark pine in western montaine systems. The gumminess of the pines’ cones prevents the wind from dispersing their seeds, a common seed dispersal method for most pines. But the Clark’s Nutcrackers are seed-eaters; they pick apart the cones and hide seeds all over their territories. For the most part, the nutcrackers remember their caches, though quite a few are intercepted by grizzlies. The grizzlies find enough of these caches that the pine nuts constitute an important part of their diet, especially as they are fattening up for hibernation. Those left behind by the nutcrackers and bears often germinate and grow into new trees.

So what does this have to do with climate change? The mountain pine beetle, always present here, is no longer being held in check by the sustained cold of winter. More and more larvae are surviving to adulthood, surviving to fly to whitebark pines and gnawing their way into the bark to lay eggs. The adult beetles carry a hitchhiker: the blue-stain fungus, which, both breaks down the trees’ resistance to the pine beetles and, when admitted into the sapwood of the pines, begins to limit and ultimately cut off the supply of water and nutrients that move through the trunk. Eventually the tree dies.

So because of milder winters, the beetles are able to carry the fungus to more trees. The trees are dying, which limits the food supply for Clark’s Nutcracker and Grizzlies. Still, some may ask, “So what?”

It is highly likely that hungry grizzlies, unable to fatten themselves on pine nuts will venture into the valley for Mc Donald’s instead, or trash, or whatever else humans have to offer. Inadvertently, the beetle’s survival may lead to increased grizzly-human interactions. And there’s more. Either because of their growing requirements or the Clark’s caching preferences, the whitebark pine is a pioneer species, meaning it grows in recently disturbed and open spaces. As it becomes established, it anchors the snow pack, causing the snow to melt more slowly and creating the sustainable water supply that we humans depend upon.

I am amazed by this story. The intricacy and complexity of the communities that surrounds us delights me. And I am dismayed by their unraveling at human hands. I wonder, of how many more puzzle pieces are we not yet aware? How many species and interactions will calve from our world without our knowing until we hear the great crash of extinction and it is too late?