UKTC Archive

Re: The Pros and Cons of Planting Trees to Address Global Warming

Subject: Re: The Pros and Cons of Planting Trees to Address Global Warming
From: ajheggie
Date: Mar 23 2020 14:31:41
Bill in forestry we try and judge the sizes such that the point at
which the mean annual increment  is the same as the current years
growth then the tree can be felled such that if it is replanted then
site maintains the maximum output. Of course after this time trees
carry on growing but it's just that the average production is not
optimised.

Trees that need to have a large girth to be valuable, like oak, have
to be grown on after this point.

It's much the same with beef cattle, they need to be slaughtered just
after their youth to maximise the potential of their feed.

Andrew

On Mon, 23 Mar 2020 at 13:11, Bill Anderson
<anderson.arb.original@xxxxxx.com> wrote:

Confusing innit?
I seem to see plenty of elderly trees that don't seem to have appreciably
increased in size during my lifetime. If they haven't increased in size it
seems to follow that they've not sequestered much carbon. At the same time
I've seen plenty of newly planted trees increase in size significantly,
suggesting they've sequestered a lot of carbon. But it's possible I'm only
seeing a very small part of the very big picture.
I need to read more, perhaps the virus will give me the time....
Bill.

On Mon, 23 Mar 2020 at 11:54, Jerry Ross <trees@xxxxxxxxxx.co.uk> wrote:

Bill -
" for most species mass growth rate increases continuously with tree
size. Thus, large, old trees do not act simply as senescent carbon
reservoirs but actively fix large amounts of carbon compared to smaller
trees; at the extreme, a single big tree can add the same amount of
carbon to the forest within a year as is contained in an entire
mid-sized tree."
https://www.nature.com/articles/nature12914

Also,
"A recent study published in Nature
(https://www.nature.com/articles/s41586-018-0577-1 ) "Trade-offs using
European forest to meet climate objectives" stated that, using existing
climate models, there was almost zero positive impact on global climate
whatever the proposed changes in forest management (including increasing
forest area). Indeed the study found that any net increase in conifers
made matters worse because conifer canopies absorb sunlight (the albedo
effort) so cancelling out the very small and temporary carbon capture by
their photosynthesis. Indeed the study shows that forest conversion from
conifer to broad-leaves has a positive impact, so restoration of
coniferized native woodland can be justified on climate change grounds
alone."
(Thanks to David Lovelace for that)

Wood pasture is the way to go.
Well actually, abandonment of all of the current widely adopted economic
models is the way to go.


On 23/03/2020 11:19, Bill Anderson wrote:
This seems a reasonably well-balanced piece Wayne. The only thing that
raises my hackles slightly is the reference to the benefits only arising
when the trees are mature. I don't think this is completely correct. The
Forestry Commission carbon lookup tables suggest that through a
plantation's lifespan, the rate of greatest carbon sequestration is
between
years 5 and 30 (after planting). This seems to suggest we should manage
our
forests/woodlands to keep the average age of the individual trees
relatively young. Their reference to maturity implies that they mean
older
than this, but perhaps I'm misinterpreting what they mean.
Bill.


On Sun, 22 Mar 2020 at 06:10, Wayne Tyson <wt750mv@xxxxxx.com> wrote:

https://www.ecowatch.com/planting-trees-climate-crisis-2645XXXXXX.html

First, I confess to not having read beyond the article. However, I
believe
that your comments will be useful in broadening my understanding of the
subject.

I look forward to your comments.

Wayne



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