Tipping Point – From Concept to Scary Reality

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Do you remember encountering, at some point in your school, a lesson in tipping points?  Phenomena the may change at a slow, regular and predictable point but then cross a threshold, or tipping point, when they can change dramatically and rapidly?  I do.  Images of the concept stick with me; I think of it as I read news of melting ice in the polar regions or the prospect of the Gulf Stream radically shifting.   Those of us owned by forests think about these things in the early morning hours.   Over the past two year’s the concept has been brought home, literally, and made real as we watch the impacts of recent drought on portions of our forests.   In our areas of mid aged Douglas fir, we are accustomed to watching some trees vibrantly thrive while others sputter along with less vigor.  We know that these differences may be caused by many things – soils, available moisture, seed source……. But until recently, experience always taught us that change in the condition of the underdog trees would be gradual and predictable.  Now that has changed.   A tipping point threshold was crossed and in several parts of the forests we have significant areas where, in the period of one or two years, 20 to 60 year old trees have begun dying – not gradually, but in the course of one or two years.  As the theory has been brought home in the shape of brown and falling needles, curling, dry bark and falling trees we now must answer the question of “now what?”  While we assume that many factors may work together to create the problem, it seems probably that drought pushed these trees across the tipping point threshold.   Is the drought a consequence of human caused climate change?  Will we ever know for certain?   Regardless, these dead trees in their even aged, monoculture plantations reminded us of something we already knew – that a forest that is diverse in age and species is better suited to a changing world than one that is less diverse.   Applying this lesson in tipping points, on all scales seems important.  Right Donald?!

img_3767  A 60 year old tree whose upper half died in the course of 12 months

img_3406  A stand of 30 year old Doug fir that crossed the tipping point and are rapidly dying