Seeing Red

NOTE: The hijacking and spread of misinformation and slander by certain commenters has led to the closing of further comments on this article.  I am however, very thankful to those many who made good points, asked good questions and provided further references, thus contributing to better public education.  Jim.

Note: This is the first of two or more articles on the extensive tree mortality now being caused by bark beetles in western North America. The goal of this first post is simply to provide necessary background on the relevant biological/ecological processes involved, so that future articles discussing climatic and other possible influences, are more understandable.


It’s mid autumn in the northern hemisphere, whose deciduous forests annually provide one of earth’s great spectacles. When deciduous trees prepare for their seasonal cold dormancy they partially recycle important elemental components of chlorophyll and the associated photosynthetic machinery, such as nitrogen, phosphorous and magnesium. Other more minor leaf pigments, which vary in abundance and spectral properties from species to species, are then temporarily exposed on the tree before leaf drop. The timing of the chlorophyll loss varies between trees, and when combined with the presence of evergreen conifers, gives the flamboyant array witnessed, typically heavy in the yellow to red pigments.

New Hampshire, USA, in the autumn

If you’ve never seen it, consider putting it on your list of worthwhile things to do in your life, as did the guy from San Francisco I once met on the Appalachian Trail in Vermont. Never mind that he carried most of his gear in a plastic garbage bag slung over his shoulder and wondered why the bears were bothering him at night when he didn’t hang his food (mostly a large hunk of cheese in a paper bag). We were instantly friends when he told me he was on the trail just to see the colors, up close and personal for a few days, in response to a magazine article he’d read.

In western North America, true deciduous forests are strictly riparian and therefore limited. The vast majority of upland forests and woodlands are dominated by conifers, all but one of which are evergreen. However, one highly important deciduous species—quaking aspen (Populus tremuloides), which turns brilliant yellow—forms groves that range in size from a few trees to vast forested expanses, typically on mid to high elevation mountain slopes with decent groundwater supply through the summer. [The largest known organism in the world is a large aspen stand in the West Elk Mountains of Colorado, USA (aspen is highly clonal, connected by rhizomes).] The greens and yellows provide a poor man’s version of fall color compared to an eastern hemlock-hardwood forest perhaps, but when combined with often colorful rock exposures, blue skies and rivers, and montane topography, the sight usually has its own magnificence.

Red foliage however, is one thing you’re not supposed to see a lot of in western North America, any time of year.

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