Tree-rings? Which trees, what trees?

All rather unscientific

I don’t really know how tree ring data is standardized. But for a single sample altitude will not have an effect, the tree does not move. When comparing two trees, say 200m appart (altitude), presumably the comparison is in the year to year variation. Not between the wood density of tree a and b. Presumably there are then some standardised trees which are correlated with measured temperatures? I guess the ideal situation would be sample over an altitudinal gradient, but I doubt they have it?

As for tree lines. I have been thinking about them. I know for a fact that tree lines are depressed by grazing. Though whether this is a factor in the northern Urals I don’t know. The rate of reaction of tree lines will also depend on longevity of tree species. Larch is relativelty short lived so should be much better than bristlecones. I worry a bit about Shiyatov’s data because the maximum change in altitude is only 60m. That is a very small change in temperature. It looks much stronger in the actual article with tree rings etc.

It works for me.

Steve: But Briffa’s level ~AD1200 is about the same as his level ~AD1650, while the altitudes of the trees are completely different. If desnity is not a function of altitude per se, as Briffa argues, and it is a function of temperature, then one should presumably apply a lapse rate to adjust.