permaculture

[Lawrence London <lfljvenaura@gmail.com>]

On Sun, Jul 31, 2016 at 4:45 PM, Toby Hemenway <toby@patternliteracy.com>
wrote:

> Thanks for this. You did the research that my slow connection kept me from
> doing. From this paper,
> http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4896614/
>
> I think it is saying that trees with thicker growth rings sequester more
> carbon than those with thinner growth rings,
>

In proportion to trunk radius? If so then your theory that late-mid
succession trees are the ones to harvest because as rings thin radius
decreases thus less tree mass and less sequestered carbon per unit of time
in the ground.
Leaving the oldest is interesting because depending on environmental
conditions growth and mass may increase or decrease. Leaving them to
continue growing may be worthwhile for extra carbon sequestering, though
unpredictable; the other factor is light availability meaning it would be
good to thin out mid size trees slowing down that are in proximity to the
oldest, thus a harvest strategy is born. Another important factor is that
old growth trees have much more economic value, particularly conifers and
of course white oak, walnut and other furniture grade species.

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.
>

Sounds right.

>
> 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?
>

As far as I can tell this may be so.  Increased carbon uptake plus "annual
basal area increment and annual mean wood density" should imply larger
growth rings, i.e. when growth slows so does growth ring size and trunk
radius.
How would a forester decide which lste-mid successsion trees to harvest? I
am sure they have it all figured out for furniture grade high dollar trees.


> 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.
>

Since it is about environmental conditions then enter permaculture
forestry. Beyond food forests.

>>> "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"

In addition to removing _any_ trees near old growth ones this sounds like a
perfect best forest management plan.

More about environmental conditions and growth rate. This adds more
complexity.

http://www.pnas.org/content/94/16/8350.full
Is There a CO2 Fertilization Effect in Tree Rings?

Another means by which tree rings are being used to test for anthropogenic
effects is by evaluating whether direct CO2 fertilization due to increasing
atmospheric CO2 (ordinarily limiting to plant growth) is presently
enhancing the growth of natural vegetation. The response of plant growth to
a direct CO2 fertilization effect has been demonstrated in numerous
laboratory experiments, usually using seedlings (e.g., ref. 20
<http://www.pnas.org/content/94/16/8350.full#ref-20>). Modeling suggests
that this enhanced growth should result in greater carbon sequestering of
land ecosystems, provided that this “beta factor” is sufficiently large
(e.g., refs. 21 <http://www.pnas.org/content/94/16/8350.full#ref-21> and 22
<http://www.pnas.org/content/94/16/8350.full#ref-22>).

Little is known, however, about whether such an effect is occurring on a
large scale in natural vegetation, where environmental conditions are
exceedingly complex. Here we review several tree-ring studies which
evaluate the possible effects of direct CO2 fertilization on radial growth
of trees growing in natural environmental settings.

A tree‑ring perspective on the terrestrial carbon cycle

http://www.wsl.ch/fe/landschaftsdynamik/dendroclimatology/Publikationen/Babst_etal_Dendrochronologia_2014
Abstract
tree-ring  records  can  provide  valuable  information
to advance our understanding of contemporary terrestrial
carbon cycling and to reconstruct key metrics in the decades
preceding monitoring data. the growing use of tree rings in
carbon-cycle  research  is  being  facilitated  by  increasing  rec-
ognition of reciprocal benefits among research communities.
yet,  basic  questions  persist  regarding  what  tree  rings  repre-
sent at the ecosystem level, how to optimally integrate them
with other data streams, and what related challenges need to
be overcome. It is also apparent that considerable unexplored
potential exists for tree rings to refine assessments of terres-
trial  carbon  cycling  across  a  range  of  temporal  and  spatial
domains.

Long Tree-Ring Chronologies Provide Evidence of Recent Tree Growth Decrease
in a Central African Tropical Forest
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4373839/
Abstract
It is still unclear whether the exponential rise of atmospheric CO2
concentration has produced a fertilization effect on tropical forests, thus
incrementing their growth rate, in the last two centuries. As many factors
affect tree growth patterns, short -term studies might be influenced by the
confounding effect of several interacting environmental variables on plant
growth. Long-term analyses of tree growth can elucidate long-term trends of
plant growth response to dominant drivers. The study of annual rings,
applied to long tree-ring chronologies in tropical forest trees enables
such analysis.

[PDF]Aboveground woody carbon sequestration measured from tree rings
http://www.rainfor.org/upload/publication-store/2013/Bowman_et_al_tree_growth_trends_TPS_2013.pdf

Above-ground woody carbon sequestration measured from tree
rings is coherent with net ecosystem productivity at five
eddy-covariance sites
http://www.ltrr.arizona.edu/~ellisqm/outgoing/dendroecology2014/readings/Babst_etal_2014_NP.pdf
Attempts to combine biometric and eddy-covariance (EC) quantifications of
carbon alloca-
tion to different storage pools in forests have been inconsistent and
variably successful in the
past.
<....>
We assessed above-ground biomass changes at five long-term EC forest
stations based on
tree-ring width and wood density measurements, together with multiple
allometric models.
Measurements were validated with site-specific biomass estimates and
compared with the
sum of monthly CO2 fluxes between 1997 and 2009.
<.....>
The observed seasonal partitioning of carbon used to support different wood
formation
processes refines our knowledge on the dynamics and magnitude of carbon
allocation in
forests across the major European climatic zones. It may thus contribute,
for example, to
improved vegetation model parameterization and provides an enhanced
framework to link
tree-ring parameters with EC measurements.

-- 
Lawrence F. London
lfljvenaura@gmail.com
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