An Aspen Fell

A Quaking Aspen fell along the Lee Vining Creek Trail. It was about 35 feet tall and forked at its base. It was the one that I used as a landmark to point out the Red-tailed Hawk's nest in a nearby Jeffrey Pine.

"See the top of the aspen tree?" I used to say. "The nest is halfway between the top of it and the top of the Jeffrey Pine behind it. It looks like a bundle of sticks against the trunk of the pine."

That was a few years ago. The aspen was growing quickly. This year I gave a Lee Vining Creek Tour, and the top of the aspen was now in the line of sight with the nest. It was disorienting at first, but actually made it just as easy to point out the nest. The highlight of that stop on the tour wasn't the nest, though, it was how fast aspens grow.

Now my landmark tree was gone. Not gone completely, but gone from its former position and function. One more change in a constantly changing riparian corridor along the creek. Instead of sifting the breeze, growing toward the sky, and providing a landmark for pointing out a hawk's nest, now it would slowly become part of the forest floor. First the smallest branches will break off and decompose, nourishing the sandy soil, and then as the years go by and as the trunk settles more and more into contact with the ground, the underside will become moist and inhabited by wood and bark eating organisms. Leaves and pine needles will drift down around it, year after year, building up the mulch around it in natures giant compost pile. Or maybe not--the next spring it leafed out and stayed green all summer, despite the bent but not broken roots.

It fell during a windstorm that was slightly unusual in two ways. Both ways contributed to the tree's demise, I think. One way it was unusual was the direction of the wind. Our prevailing winds come from the southwest--especially the big windstorms. Instead of coming from the southwest, this wind came from the south. This slight change in the angle of forces on the tree could have strained the roots in a new way--a way they weren't able to withstand. It is possible the giant new wall Caltrans built at the south end of Lee Vining had something to do with it as well.

The other, and probably main way in which the windstorm was unusual and caused the fall of a tree that had withstood winds of equal magnitude in the past, was the timing. It was in September. All the trees still had leaves, and thus caught the wind like sails and bent the trunks more than usually occurs when the leaves are gone after October. To appreciate the significance of this, you must understand that the high wind gust recorded in Lee Vining was only 69 mph. I say "only" because Lee Vining typically gets wind gusts in excess of 70 mph several times a year. But these big winds usually happen when the trees have no leaves between October and May. A quick look through the past 5 years of weather records showed that this was the biggest wind gust recorded in Lee Vining as early as September.

Many other trees fell during this windstorm. Several Lombardy Poplars in Mono City fell, including one that crushed a car. Now, Mono City is known for its big winds that come barreling down Lundy Canyon. Stories of people losing or gaining stuff in their yard are common after a big windstorm. But you don't usually hear about trees falling over. This windstorm, which hit approximately the 80 mph mark in Mono City, toppled several trees.

Farther up toward the mouth of Lundy Canyon, where the moraines narrow, a pine fell (I was told). It was dead, and perhaps just time to go. Maybe the southerly direction of the wind can explain it. I have not personally investigated the direction it fell--at the base of Lundy Canyon it is possible the wind direction was different there. Regardless of the reason, the wood from that tree will now heat a nearby home instead of providing a home for woodpeckers and owls.

Meanwhile, numerous seedlings and saplings of pine, poplar, and aspen are reaching for the sky to take the place of the fallen giants. They too, will fall one day.