WASATCH ENVIRONMENTAL UPDATE: “Aspen Catkins and Aspen Prehistory”

Wasatch Environmental Update for April 1, 2018

By John Worlock

Aspen Catkins and Aspen Prehistory

It has been a lovely warm spring day here in the Salt Lake Valley, and I have been out in my aspen grove, inspecting and admiring their catkins.  It’s about time, as here at the altitude of 4800 ft, the catkins are already beginning to drop. I have harvested a few and brought them indoors for inspection. As expected, they all turn out to be males.  Aspens are called dioecious, and that means that they are single-sex trees.  The catkins on my trees have the tiny organs called anthers, which emit the dusty yellow pollen.  It’s a useless expenditure of energy on their part, as there are few other aspens in the neighborhood, with low probability of being female, as well.

My mature trees are bursting with catkins, which I mistakenly took as t ‘a sign of health.  But now I know that it is stress that inspires the aspen to burst into flower.  I have known that my trees are stressed, and I have been spending some serious cash each season, to buy protection from borers, fungus and other threats.  Aspens don’t quite like these low altitudes, as the warmth aids the reproducibility of their enemies.  But even at their normal altitudes, the warmer winters are not good for them.  Yes, we’re talking about global warming.

It’s tough for plants to adjust quickly to warmer winters.  They might benefit from longer growing seasons, but it seems that their enemies are the primary beneficiaries.  So yes, my aspens are not the only ones that, after evolving for many millennia, are finding 21st century life challenging.

We’ve just mentioned many millennia, and indeed aspens predated the arrival on the North American continent of the first humans. The huge aspen colony we know as Pando is not only the largest living being, but is also estimated to be the oldest, with an age of some 80,000 years, having lived through at least one ice age.

It’s not obvious how we calculate such an age, since none of the individual trees in that colony have lived so long. But there it is, and we’ll be studying that question in the next few weeks.

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