I think it is saying that trees with thicker growth rings sequester more
carbon than those with thinner growth rings, even though the thin growth
rings were more dense. But someone else may want to look that over, as I am
not at my best due to meds I am taking. The trees were grown under “marginal”
conditions, so it may not be comparable to a healthy low-elevation forest.
Here are excerpts (HE is “higher elevation” and H is “high elevation”)
> Mean tree-ring width and wood density rates were 2.60 ± 1.43 mm years−1 and
> 0.77 ± 0.12 g cm−3 years−1, respectively, with the HE population having the
> larger values of the two variables.
>
> P. cooperi trees at site HE showed greater cumulative carbon than at H
> during the analysis period; these were ~300 and 200 kg at 60 years,
> respectively, with a tendency to continue increasing (Fig 6). In addition,
> site HE had a significant difference in annual carbon uptake (Table 3).
> Although wood annual density and basal area increment were not
> statistically significant, both variables tended to be greater at HE than H.
> larger values of annual carbon uptake are directly associated with larger
> values of annual basal area increment and annual mean wood density
Isn’t this saying that the thicker rings sequestered more carbon? What I’m
not quite understanding, though, is why a tree grown at higher elevation
would have thicker growth rings.
I will look over some of the other links as time permits and if I think it’s
really worth pursuing this much further. I have satisfied myself that carbon
sequestering is not about young or old, it is about environmental conditions
(Duh!). And of course we want old growth forests and trees. But if trees must
be cut, we need criteria to guide us, and it seems to me that
late-mid-succession trees that are beginning to slow their growth (and the
growth of nearby trees) would be the ones to cut. Not the youngest, not the
oldest.