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Discussion in 'Plants: In the News' started by Daniel Mosquin, Mar 16, 2010.
What are the long-term effects of rising carbon dioxide levels on plant communities?
Just attended a presentation in Eugene, Oregon, last Saturday night, given by Dr. Sillett and Dr. Van Pelt, about redwoods and 4 other tallest conifer species.
A couple of charts showed that redwoods, for example, have been growing remarkably well the past 50 years. Possibly associated with CO2 levels.
Looks like the last growth spurt that was at all comparable, was back in the 1600s or so.
: - )
Was there any speculation as to what made that growth spurt back in the 1600's?
There was a volcanic eruption in Peru in 1601 that had a significant impact on sulfur and carbon dioxide levels, leading to bitterly cold winters documented in Europe, and of course acid rain. Sociologically, famines resulted from the cold, the acid rain, and the gloomy skies, but we might suppose that some trees would have benefited from increase in rain fall and a bit of the greenhouse effect from atmospheric volcanic ash.
I did not recall a suggested cause being mentioned for that.
One question I had, where the answer was associated with a date or cause, was about dead tops. I asked if they ever core sampled the dead tops of redwoods, to see if there was any relation. Some groves have quite a few standing dead tops.
Apparently a lot are associated with the year 1976. Apparently an unusually dry year around some coast redwood groves.
Likely that I will try and find out about the 1600's and if any cause is suspected, because I was curious myself about that one.
Doesn't match too well with the other recent report on Redwoods not doing so well!
Matches up real well when we read the facts. Notice that the article you linked to, begins with "potentially" in the first sentence? "potentially" in my way of thinking, equals has not happened yet.
On the other hand, the data about the current century's growth recorded in the growth rings is an absolute, that was sampled and researched.
It all depends on what other conditions the lack of fog is associated with. The presentation in Eugene also briefly covered the fog aspect too. The fog article, seems to convey looking forward with concern, rather than looking backwards at the growth that did happen over the past 100 years. The word "may" is repeated, and we see that the study and researchers have yet to "calibrate" and "correlate".
Odds are that the redwoods will have a growth decline at some point, and the 400 years of ring data showing growth surges, also showed growth declines. The fluctuations must have occured for milleniums.