Whitebark Pine Seeds and Grizzly Bears

“Losing whitebark pines” is the title of a 3-page article in the Idaho State Journal Sunday, August 5.  According to the article, “Whitebark pine is … the product of a ‘coevolved mutualism’ with the Clark’s nutcracker.”  Each Clark’s nutcracker can cache tens of thousands of whitebark pine seeds over a wide area.  Red squirrels also “cache large quantities of seeds”.  Squirrel seed caches are a major food source for grizzly bears,  especially when they are storing fat for hibernation.  If whitebark pine seeds are not available, grizzly bears look for high-calorie food sources at lower elelvations, where they are more likely to be killed because they meet more people.

In past centuries bark beetles have been a useful thinning mechanism for pine forests.  However, global warming has allowed bark beetles to complete a full life cycle at higher elevations in one year instead of two.  They are now a serious threat to whitebark pine populations in Yellowstone Park [and around Galena Summit near Stanley, Idaho].  Whitebark pine are also becoming more infested with blister rust.  The trees may be more susceptible to blister rust when they are stressed by drought.  Global warming is allowing lodgepole pine to compete with whitebark pine at higher elevations.  Lodgepole pine have evolved effective defences against the bark beetle, so the beetle infestation is an advantage for them.  The resin-sealed cones of lodgepole pines open with fire, so they are not as nutritionally rich nor easily available to birds, squirrels, or bears.

“Grizzly bears were delisted from protection under the Endangered Species Act in March of 2007, after 32 years, because … the bears were thriving in the greater Yellowstone region”, according to the ISJ.  If the whitebark pine seed production collapses, much of the hard work to restore a viable grizzly bear population in the greater Yellowstone area could be undone.

Like many other effects of human activities, global warming helps some species and hurts others.  If you want more blister rust, bark beetles, and lodgepole pine, then promote global warming.  If you want whitebark pine, red squirrels, Clark’s nutcrackers, and grizzly bears to at least hold their own, then do what you can to slow global warming.

For more information, read the full article.  Also, High Country News is a bi-weekly regional newspaper with frequent coverage of effects of global warming in the Intermountain West.


1 Response to “Whitebark Pine Seeds and Grizzly Bears”

  1. 1 http://www.Beste-taufgeschenke.de/ March 21, 2013 at 1:29 am

    Wow that was odd. I just wrote an incredibly long comment
    but after I clicked submit my comment didn’t appear. Grrrr… well I’m not writing all that over again.

    Anyhow, just wanted to say superb blog!

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