SITKA, Alaska — Pacific Northwest Research Station researcher Dave Nicholls spent the afternoon with a local 4H youth group in Sitka, Alaska. Ten 5-to 15-year-old children attended. The lesson topic was “How do Trees Grow.”
The primary goal was to show students examples of how trees can grow differently depending on tree species and environmental conditions. They also talked about the Tongass National Forest, which surrounds Sitka, and the differences between old growth and young growth forests. The teaching module was part of a phenology lesson in which 4H children in Sitka learn about the timing of natural events such as seasonal changes in deciduous trees, berry growth and harvest, and weather patterns.
Activities included counting tree rings with a magnifying glass. Some children counted more than 200 rings in a single sample! Samples from old growth trees included more than 400 growth rings to look at. Props included round wood samples (i.e. tree cookies), sawn lumber sections, and increment cores. The students learned about different forms of wood containing growth rings and studied a variety of tree species.
The inquisitive students asked some very perceptive questions, such as:
- “How can you tell the age of a large tree using a small increment borer?”
- “How can you tell a true growth ring (1 per year) from false rings (2 or more per year)?”
- “Can you use sound waves to test a tree and determine its age?”
- “Do you need to wait until a tree is harvested to determine its age?”
- “Does a tree make a growth ring during its first year (as a seedling)?”
- “Can you tell a species of tree just by looking at its bark and needles?”
Perhaps there were some future foresters and wood scientists in this group!
For more information please contact PNW Research Station researcher Dave Nicholls.