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Global warming, Carbon Dioxide

Birch vs. Aspen; the unexpected carbon outcome

By Joshua S. Hill

Thursday, September 20, 2007

One of the fundamental rules of an issue such as global warming is that there are sub-issues that are going to be overlooked for a variety of reasons. Primarily, and the one we are most accustomed too, is the sheer force of will of some to ignore what is going on around them. However just occasionally we find that we’re killing something unexpectedly.

According to University of Michigan microbial-ecologist Donald Zak and his colleague’s, birch trees are likely to overwhelm aspen trees in northern forests due to continued and rising levels of carbon dioxide in the atmosphere.

Now let me just state from the get-go here, this is not an issue that is going to win me a Pulitzer or help Al Gore finally gain the Whitehouse. This issue is though another in a continuing string of unanticipated results caused by the human influence on the planet. My overriding belief is that, if I could manage a non-lethal and morbid removal of all humans from planet earth, I’d be a happy man.

The research being conducted at a 38-acre experimental forest in northeastern Wisconsin has provided Zak and his colleagues with invaluable information about the processes that trees undergo with heightened carbon dioxide levels. Ever since 1997, the team has been pumping higher levels of carbon dioxide in to the canopy of the trees to simulate the rising levels in reality. The make-shift forest contains several thousand trembling aspen, paper birch and sugar maple trees.

What they have found is that the trees grow about 45% faster than the average aspen-and-birch, and as a result the trees need to sustain their growth by delving deeper and faster to forage for more nitrogen.

Zak, a professor at the U-M School of Natural Resources and Environment and the Department of Ecology and Evolutionary Biology, found that birch trees increased nitrogen acquisition by 68 percent, so as to maintain the growth fermented by the enriched carbon dioxide in the canopy. The aspen though, only managed an increase of 19%.

"The implication from that experiment is that it could alter the abundance of birch and aspen—in places like Michigan—by favoring birch," Zak said.

The extraordinary conclusion from this experiment though is not one that is going to be thrown at the feet of global warming naysayers, but rather provide hope to those of us who do not want our children to enter in to a world on the brink of destruction.

Current ecological future models take in to effect an accelerated growth for trees, however they add a stopping point where they believe the search for an ever increasing source of nitrogen will halt. Zak and his colleagues, in a separate study being published online in the Proceedings of the National Academy of Sciences, believe this to be untrue, and say that trees will continue to grow at a steady rate with no drop off.

The importance of this is what I’m excited about. The great northern forests are natures own ‘carbon sinks’, meaning that they draw the carbon dioxide from our atmosphere and store it for a time within their tissues.

The end result could be that, if the continued growth rate continues, and is allowed to continue, the forests of the north could help dampen the heat-trapping effects that are causing the global warming planet wide.

"Some of our initial assumptions about ecosystem response are not correct," Zak said. "Elevated CO2 increases the ability of these forest trees to get limiting nutrients out of the soil. And that's a mechanism that's not in our current conception of how CO2 will affect the way forests work."

One can only hope then, that instead of seeing growing forests as an impinging doom for suburbia or as an added fuel source that people will see the need to let the forests grow to help create a future.

Other articles by Joshua Hill

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	Web canadafreepress.com

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