Scientists Studying Growth Rings
For scientists, like Dr. Fir, looking at the growth rings of a tree is just like looking at a scrapbook of the tree's life.
To study tree rings Dr. Fir looks at something called a "cross- section." He gets this by cutting right through a tree. This way he can see all of the rings from each year of the tree's life. Just imagine looking down at a stump of a tree.
The tree's age can be figured out by counting the pairs of light and dark rings. It's easier to see the dark rings so they are usually the ones used for counting. Dr. Fir starts with the first dark ring in the centre and counts out to the last dark ring before the bark.
To help figure out what climate the tree grew in and what the environment was like, Dr. Fir looks at each ring:
- Thickness: How wide a ring is can tell you if the environment was good or bad for the tree to grow in. In years when the amount of rain and temperature were good a tree's rings are wider. In bad years a tree's rings are thinner.
- Shape: If rings start to become thinner on one side than the other it probably means the tree is leaning over to one side. High winds or a big storm can cause a tree to lean.
- Dr. Fir also looks for strange marks, like scars, and other "pieces of evidence." Scars can be left by insects or disease. A forest fire can leave burnt marks.
- Dr. Fir uses a computer to measure the width of rings up to 0.01 mm and to find other things he can't see by just looking at the tree. This helps him get the most and best information about the tree that he can.
Next: Help Dr. Fir finish his tree study report >>
