How To Read Tree Growth Rings

How To Read Tree Growth Rings

– [Curtis Smith] Welcome to Southwest yard and garden. I’m Curtis Smith. A few weeks ago we answered a question about tree rings using this piece of tree right here. George Duda with New Mexico State
Forestry explained, what these rings will tell us. And we’re here again with George
to learn more about tree rings. And George this is from what kind of tree? – [George Duda] That’s a green ash. – [Curtis] Green ash. And how old is it? – It’s about a hundred and ten years old. – And
then right next to it we’ve got a different tree. – This is a Douglas fir,
from northern New Mexico. – It’s a little larger – Mm-hmm. – How old is that it’s about?
– Two hundred and twenty years old. -Okay, and then you brought us these as well.
This is… ponderosa. – This is a ponderosa pine. – And how old? – About 75 years. – 75 and we compare… – To 220. – So it should be smaller it’s smaller. But this one now. that’s our state tree
that’s a pinyon pine and the rings were counted under a binocular microscope the
things are so tight and I came up with 214 so it’s nearly the age of this one
that’s correct and what’s the difference the
environments the species water this grows where it’s dry and this grows was
moist and so it grows much faster so the rings are spaced much wider much wider a
lot easier to count much easier to go let’s look at these rings over here this
sash is probably a good one to look at to see the rings mm-hmm
how do these rings grow well there’s that there’s the spring would to the
light the white part there we see is summer wood and as the summer progresses
and it gets drier you see a darker ring so rings really are a combination of the
two one ring one year is the summer wood spring wood and the summer wood okay do
all trees produce only a single ring not all trees because I’ve got an oak tree
in my front yard that puts on about three growth flushes every year so I
would suspect it makes three rings a year sure does so you have to know the
tree if you’re going to try and count years using the rings and depend on
those years and so in this one you said it goes back a long time 110 years 1890
but we also as we talked about in the question and answer segment a few weeks
ago we see the history of New Mexico in Harris if we look at the outside of the
tree just under the bark year 2000 and we go back about 20 years and we see a
cluster of rings that are very tight and very small that represe
hence the drought of the 80s going back another 30 rings or so we come back into
the horrible drought of the 50s it shows it very clearly we go back another 20 or
so years and hear of the Dust Bowl days very dry period of time a horrible time
in the West and going back even further to when the tree was very young there’s
a band of very tight rings about 1900 there was a drought in that period of
time also interesting the tree tells a tale the trees tell the tale and I see
it split here it’s drying as wood dries it split splits and so that’s just a
natural thing here has nothing to do with the ring so it does it does not and
this Douglas fir has a split but that tells us something about history so what
we call a pitch seam and the tree as a tree sways in strong winds it needs to
flex a little bit so the tree will sometimes inside will crack and pitch
forms in this crack and actually acts as a lubricant so the tree can flex in the
wind and survive the two hundred twenty years of wind and weather and so this
one formed while the tree was still standing yes it did whereas the one over
here on the ash tree formed after it was going out very interesting and we also
see something interesting in this Douglas fir we’ve got these marks here
and here those are brett where branches were forming and where it was cut just
happened to cut through those branches so you can see how the branch was was
growing in relation to the trunk of the tree and it disappeared here because it
went outside cut okay in the truck grew around the branch as a trunk got larger
and larger it just included the branch in it so we can see that history of the
growth of the tree as we look at this section of tree is correct that was also
because of a lucky cut a lucky cut this pinyon also tells a story too it’s got
something going on right here yes it’s probably an injury a mechanical injury
and when it happened the tree is trying to heal itself and cover up that injury
and we see some mast pitch and the tree is sealing itself off so within
continued growing it have been a broken branch broken in the wind but this kind
of thing happens in urban areas sure does these trees tell us some very
interesting things thanks for interpreting what the tree tells us and
telling us about the tree rings you hear Curtis thank you


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