Global wierding - Page 8 - PeachParts Mercedes-Benz Forum

aklim · #**106** 07-11-2012, 08:26 PM

Quote:

Originally Posted by spdrun

Fine: let the scientists try to disprove it, and don't burn them at the stake for it. But until it IS disproven, may as well work with what we've got and reduce CO2 emissions. What do we have to lose?

* Wars in Middle Eastern pestholes, and the expense of keeping and feeding our military parasites there

Yes and it costs nothing? Really? Before we go down a road, lets try form the idea and not justify the idea. I thought the way was that if you propose an idea, you prove it and not I disprove it?

Sorry, that dog won't hunt. We have had wars for a long time. Since before recorded history and oil wasn't a factor then. People have been fighting. Remove oil as a factor and we will fight still. Just over a different item.

Dudesky · #**107** 07-11-2012, 11:44 PM

Quote:

Originally Posted by Botnst

Lie? No. But there are sure as heck easy to misinterpret. Let's say you're at a high latitude (above 30 deg lat). If you consistently take an increment bore from either the NS direction or the EW direction with regard to the tree you would come up with two different trends. See, latitude affects growth differentially. So does slope aspect. So does hydroperiod. And so does species. Also, individual trees within a stand will vary from each other. So the best thing to do is take a core from 90 deg off the same tree and stay consistently within a species and within similar slope aspect and hydroperiod (and soil type, etc).

Then there's the measuring of the rings themselves. One must recognize false rings and missing rings. One must recognize early wood from late wood. Consistent measurement requires that the same positions be consistently measured.

Then there's removal of autocorrelation. See, trees grow quickly when young and slow as they get older. So ring widths are naturally different, and narrowing over time. So to get them on the same time scale with respect to growth rate you have to remove the correlation of growth rate and age.

It is NOT simple. It is easy to make mistakes. It takes a long time and a lot of work to build a useful chronology. Univ of Arizona is probably the premier repository and analytical lab for dendrochronology. I suggest perusing their website for anybody interested in how tree rings are studied.

I knew that...

Botnst · #**108** 07-12-2012, 07:58 AM

Quote:

Originally Posted by engatwork

This one was taken out of the yard a couple weeks ago (long needle pine) and provides a good example of what B is talking about.

That looks like a pine slab. Maybe loblolly? It does indeed show rapid growth in the earliest years and then shuts down pretty quickly. Then it opens up (wide rings) for a number of years and then slows again. What I see is modern forest management. Trees were free to grow until the canopy closed and the rings got quite compacted. Then somebody selectively harvested the forest and left that tree standing. That's the second set of wide rings. Then the canopy closed again and the rings narrowed.

But you know what? IT could be any number of things. It could be that the tree grew up next to an impervious surface (driveway, road, etc) and struggled for water and nutrients as it got older.

Or maybe it was climate cycles.

Etc.

This is why the dendrochronologist should take numerous cores off several trees of the same apparent enviro circumstances and of the same species. Depending on a single sample to drive interpretation is a waste of effort.