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MLA Full: "Life as a Tree!" YouTube, uploaded by SciShow Kids, 18 September 2018,
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Did you know you can read the story of a tree's life? By looking at a tree's rings, you can figure out way more than just how old it is! Jessi and Squeaks are here to show you what to look for next time you're on a hike and find a tree stump!

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Boy, Squeaks, it's been a great day hiking in the woods, but I think I'm ready to go home now.  What are you looking at over there?  You're counting?  Well, there's stuff that we can count back at the Fort.  Oh, you're counting the rings of that tree stump, and you're already at 64!  Well, you should keep going, then. 

You know, trees seem like a pretty ordinary everyday thing.  We usually don't think about them much, but they're really helpful.  They help clean our air, they give us wood and paper to make tables and chairs and books, and did you know they're great storytellers?  You just have to know how to listen.  You're right, Squeaks, trees can't talk, but they can still tell us a lot without using words.  When we study a tree, we can learn all sorts of clues from it, and by putting together all the clues, we can tell the story of its life.

See, during a tree's growing season, that's spring and summer, the tree will get taller and wider and add another layer of wood around its middle.  Those layers are the rings.  Some trees live in warmer places where they can grow all year long so they don't have rings, but this one sure does.  They're kind of like a secret code.  We just have to know how to read them.  

Early in the growing season, the tree grows a lighter colored wood called earlywood and then in the late summer, it grows a darker wood called latewood, and I bet you can guess where those names came from.  One light ring plus one dark ring make up one year in the tree's life, which means you can count how many years the tree was growing and you can see what those years were like.  

Let's take a look at the rings on this tree stump.  How many rings did you count, Squeaks?  78!  If the tree was 78 years old when it was cut down, it must have some pretty exciting stories to tell and it recorded all those years for us in its rings like a little book about its life.  The rings in the middle here are the earliest ones.  It looks like the first few years of this tree's life were really great.  It has nice, wide, evenly spaced rings, which means the tree had some healthy growing seasons, and then I see some thin rings over here.  That means the tree was having a tough time.  It didn't get everything it needed, so it didn't grow as much.  Maybe it didn't have enough sunlight or maybe there was a drought, which means that this area didn't get enough rain, or insects might have eaten a lot of the tree's leaves that year which made it grow more slowly, and then the rings get wider on one side, so just when the tree was starting to grow up, something started pushing on it and it leaned to one side, so it grew thicker on that side to help support itself, and then there are a few thin rings right after that, and then our tree evened out and grew some nice, thick, even rings.  

Maybe some other trees had been pushing it aside and crowding the sunlight, and then maybe they fell down, so our tree finally had all the sunlight it needed.  Oh, wow, it looks like there might have been a small fire after that, a whole side of the tree was scarred, but it kept growing new wood over the scar every year.  This tree had some good years and some really tough ones, but it stuck it out and it kept growing.  It lived a long, full life until it was chopped down. 

Oh, don't worry, Squeaks, we don't have to chop down a tree to count its rings and learn all about it.  Scientists have a special tool for that.  It's called an increment borer, which looks kind of like the letter 'T'.  By putting the long, thin bit into the tree and turning the handles around and around, a scientist can get the increment borer all the way into the center of the tree and pull out a thin strip of wood called a core.  That doesn't hurt the tree too much, because these cores are tiny.  They're less wide than my fingernail but they can tell us the story of that tree's life just like a tree stump would.

We just looked at the life of one tree.  Now, imagine if you had lots and lots of cores of trees from the same area and looked at all of them together.  If the same two trees survived a fire or a very cold year, we can find out by comparing their rings and with enough cores, we can even figure out exactly what year those things happened. 

There are scientists whose whole jobs is to study tree rings like these.  One thing they do is match up different samples to each other to figure out what happened in these trees' lives.  We can even compare histories from the trees with records people have kept of the weather.  Those records usually go back 100 or 150 years, but some trees are much older than that by hundreds or even thousands of years.  

The more samples scientists have, the more they can learn, both about how an area's weather has changed over time and about big events like droughts or insect infestations.  That's a much bigger story than the life of just one tree.  

Trees go through a lot of rough times that make it hard for them to keep going, but they keep growing and growing all through the droughts and the insects and the fires.  I think I'm going to try and be more like a tree, and you know what, Squeaks?  I thought I was ready to go home, but I think I wanna spend some more time with the trees.

Thanks for joining us.  If you want to keep learning and having fun with Squeaks and me, hit the subscribe button and we'll see you next time.