Tree Rings and Climate Lab

Tree rings are a good way to study past and present climate. They are proxy indicators of climate change, but can be used to study other climate events as well. You will need several handouts for this lab. The student handout is on this google doc. Note: There are a lot of regional-specific questions in this lab. You will need edit for your own tree cookies and region.

You also need the document “Reading the Rings of a Tree” as a student reference sheet.

You can use large or small tree cookies, but larger ones typically have more interesting data and weather, insect or fire events.

Finding Tree Cookies

  1. You can purchase tree cookies on Amazon or Etsy. Its easier to buy them, but kids get more out of the lab if you can find local tree cookies.
  2. Wood-shop or career-tech construction classes. We have wood-shop on campus and the teacher had a spare log and cut a bunch of tree cookies for me. Shout out to Leonard Friedman, woodshop teacher extraordinaire!
  3. Find or buy a log and use a chainsaw to cut your own cookies.
  4. Wait until after Christmas and use a discarded live (now dead) tree.
  5. Ask a tree-trimming company for branches or trunks of trees they are removing.
  6. A firewood company may sell you unsplit logs.
  7. A local college or extension may have some tree cookies to loan.
These tree cookies are from a local pine and show evidence of insect infestation.

Other Supplies

Setting up the Lab

Prepare tree cookies by placing pins on some of the dark rings. This helps students identify and measure between rings. Reading rings is actually harder than it seems. Students (and teachers) have some difficulty with this. When they are counting the number of rings, tell them to ESTIMATE and do the best they can, because its difficult.

If you have hard wood, you may need to use a hammer and thumb tack to make hole before then putting in one of the other pins.
Customize your pins based on your location. This tree cookie shows severe drought in CA in the pink, black and blue pins and some El Nino years earlier.

If you choose to protect the trees with varnish, I recommend flat varnish, because gloss or semi-gloss reflect overhead classroom lights and make counting more difficult (learned this the hard way)

Copy the paper tree cores on card stock or laminate for durability. That way you can use for multiple periods and multiple years.

Measuring a paper tree core.

Preserving Tree Cookies

If you want to preserve your tree cookies to use for a long time and also prevent bugs and pests, the following are directions from APES teacher Mark Case:  “I make tree cookies regularly. Step 1: soak the cookie in antifreeze for about a week. Make sure it is very well penetrated. Eggs and larva die. Step 2: Freeze for 72 hours in a deep freeze. Step 3: use a solar dryer. Any type tote and a piece of glass or plexi glass over the top in the hot summer sun. Step 4 let it dry for at least a week before you coat it with poly. “

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