Thursday, December 16, 2010

Hybrid Oaks: Evidence of Climate Change (Just Not The Kind You Think Of)

This is an old article and it covers something we have discussed before, but I think it's cool that the topic reached the "mainstream media," if only for a moment - and even if there are some of the mistatements and errors we expect when reading or hearing a mainstream news report of a natural resource issue.

In 1954 Rudy Drobnick and Dr. Walter P. Cottam discovered some hybrid oaks growing in warmer, wetter pockets of the Wasatch and Oquirrh Mountains.  The question became: Hybrids of what x what?  The two determined that these trees were a naturally occurring cross of shrub live oak (Q. turbinella) - not canyon live oak as the article states - and Gambel oak (Q. gambelii).

<< Broken record time:  I contend that it would be bigger news if they found oaks that aren't hybrids to some degree or another.  >> 

Two things are very cool about this specific discovery:

1) Shrub live oak does not grow in the areas where the hybrids were found.  Shrub live oak is found only in places that are considerably warmer.

Drobnick and Cottam deduced that the climate 5,000 to 7,000 years ago was much warmer than it is today, and that Q. turbinella's  range expanded into this area, where it proceded to do what oaks do:  hybridize with oaks of another "species."

Then, as the climate cooled, shrub live oaks died out in this area, unable to withstand the cold.  However, some of the shrub live x Gambel hybrids clearly had enough of the Gambel oak cold hardiness to remain, grow, and produce offspring.

2) The issue so excited Cottam - who was by no means a young man at that point - to devote much of the rest of his career (and all of his "retirement") to producing and growing hybrid oaks.  Unlike other places where the work of geniuses like Helge Ness and J. Russell Smith were cut down or paved over, the University of Utah has done an admirable job of preserving and continuing Cottam's legacy.

Now, the article states that some of these hybrid oaks are 5,000 to 7,000 years old.  I'm having a wee bit of trouble believing that any individual hybrid oak trees are that old.  I could be wrong, and that would be awesome.  But that would put these oaks into bristlecone pine territory for longevity, and I just don't think that can be true. 

What's much more likely is that these trees are the offspring of hybrids created 5,000 to 7,000 years ago.  From the standpoint of the mainstream media that's not as exciting as 5,000 year old trees, but to me it's infinitely more exciting.

Yes, there's a lesson in here about how the Earth's climate has gone through very large shifts in relatively short periods of time, with no help or input at all from humans.  Lesson received.

But more to the point, at least as far as a "Quercophile" like me is concerned, is that this Utah episode is a window into how oak "species" are formed, how they change over (relatively short periods of) time, and how elastic they are. 

How many thousands of times has this sequence been repeated?  Climate changes. Range of oak "species" A expands.  A hybridizes with B.  Climate changes back again and the "pure" A's die off along with those AxB crosses that mostly have A's characteristics, leaving behind a new population of AxB crosses that have predominantly B's characteristics. 

The AxB hybrids both back cross to B, infusing the population of B with many traits of A and more variation, and self-pollinate to create an entirely new "species."

The really cool thing:  It's happening right now, as we speak.  Well not as I speak, since it's winter and about a jillion degrees below zero.  But you know what I mean.  Oak species are crossing, adapting, and changing continually in their heroic - but increasing quixotic - attempt to sustain us.

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