Counting Tree Rings

Determining the age of a tree by counting the growth rings is often easier in theory than in practice. I photographed a stump from a recently cut tree. The rings are clearly visible – no saw marks or decay to complicate the view. But – the stump is not perfectly round and the rings in the most recent years are tightly spaced (i.e. the tree was struggling as it got older…maybe from disease).

I took zoomed views from various perspectives. How old do you think the tree was?

It’s often easier to use count the rings in tree cookies (cross sections of tree branches less land 5 inches diameter that are round….often less than a decade of growth). This example illustrates the increased challenge counting of rings for the whole tree!

Field Trips in the Rain

Last week, I volunteered for two elementary school hiking field trips at Howard County Conservancy’s Mt Pleasant Farm….and it rained both days! On Monday it was kindergarteners and the ‘hike’ was shorted from 40 minutes to 20 minutes and accomplished in mostly the nature center. We started out on the terrace above the nature center looking out over the Honor Garden…talking about trees with leaves (and looked at leaves on the ground). Then we walked quickly around the front of the building to get to the nature center…and were wet enough already. Inside the nature center there were animal skulls and pelts…seeds and leaves…preserved insects…

And tree cookies.

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When I talk to kindergarteners about tree cookies, I take time to explain what they are…and that they are not to eat! We count the main rings on the Royal Paulownia and then note that the other trees grow more slowly. My favorite is the dogwood because the rings are not as regular the other samples. The children are always enjoy learning about sugar maples…and maple syrup.

The rest of the time that would have normally been hiking was spent observing and hearing about Ranger, the barred owl.

On Friday, it only sprinkled a little on the first hike with second graders while we were out and about in the meadow. It was a very cloudy day.

During the second hike, it started raining. The children were dressed for the weather and more than half of them had umbrellas. We were in the meadow collecting and analyzing soil samples when it started raining. We decided we’d done enough samples and went to learn about the rocks by looking at an old stone wall. We started making our way back to the nature center by way of the goat and chicken enclosures…noting what the animals were doing (both enclosures have shelters and that’s where the animals were…out of the rain). We stopped briefly at the old stump in front of the farm house and discovered a snake skin fragment. Then we headed in to the nature center to see the living black rat snake (Onyx), a snake we see frequently at Mt Pleasant. They were ready for lunch too!

These were my last elementary field trips for the fall season. Even with the challenge of rain, they were good experiences…for me and for the students.

A Stump at Staunton River State Park

In a grassy area near the visitor center – I noticed a stump. Someone had left a pumpkin on top, probably while they were decorating for the Star Party. I walked over to get a closer look. It looked like it had been cut down recently.

The rings stood out a lot more than the rings of the Silver Maple at Mt. Pleasant. This stump had not been sanded either. I counted 74 rings but there were some very narrow ones from recent years that were harder to count….so I estimated it was about 80 years old when it was cut down.

The people in the Visitor Center told me that it had been cut down recently and that they thought it had been planted near the time the park was created in 1936. But they didn’t know what kind of tree it was. The next morning, I talked with the park manager that was manning the outdoor grill at the Cantina for breakfast and found out that it was a Post Oak and he had counted 84 rings when it was first cut down. The CCC did most of the work when the park was created so it is likely, because of its location, that it was planted by them. The tree had leafed out last spring but then dropped all its leaves during the summer. It had been struggling for the past few years and looking at the stump shows the evidence of that struggle in the outermost rings.

Steps in the Silver Maple Stump

The Silver Maple Stump that I wrote about a few days ago has been made accessible for shorter visitors! There are steps cut into the side that was not sanded to reveal the tree rings!

We looked at dogwood and Paulownia tree cookies to learn how to count tree rings and notice how the rings look different – the spacing, the shape, etc. The kindergarteners were thrilled to climb up onto the stump – three at a time – to gather around the center and count 5 rings from the center. The tree was not very big when it was 5 years old!

They were also surprised that the water on top of the stump was coming up from the roots…and that the stump was not perfectly round. They also noticed some ants that made their home near the outer edge of one of the steps…and a daddy longlegs spider climbing the steps too.

On the down side, when the steps were cut, additional rot was found so the stump may not last very long…I’ll just enjoy it as a field trip stop while it lasts.

Silver Maple Stump

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Last month, two silver maples were cut down near the farmhouse at Howard County Conservancy’s Mt. Pleasant Farm because they were dropping large limbs and endangering nearby structures. One of them is conveniently located between the drive that loops around the farm house and the Honors Garden. When I first looked at it, I was thrilled that the stump could be used to talk about tree rings generally…and the history of Mt. Pleasant specifically. The first challenge was that the saw marks were so deep that it was difficult to see the tree rings.

Fortunately, several volunteers stepped forward to sand the smoothest part of the stump so that the rings would be easier to see. It was still a little challenging. The stump includes rotting areas and splits near the center. The stump is still very much alive as well – with sap coming to the surface as the roots continue to collect water and nutrients from the soil. The first time I attempted to count the rings it was a cloudy day and the size of the stump was a bit daunting. I realized I needed a step stool to see the rings toward the center. I came back on a sunny day and climbed up to sit on the stump when I realized that the slope was not going to work with my step stool. I managed to count 124 rings!

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I made a strip of lightweight cardboard with years on it (counting from the outermost ring) and a page that talked about tree cookie parts. For kindergarten and 1st grade students that hike by the stump – we’ll talk about counting rings and then either count 5-6 rings from the outer edge (how much did the tree grow since you were born) or from the center (how big was the tree when it was as old as you). For adults, I have a time line for what was happening at the farmhouse and Mt. Pleasant over the past 124 years and plan to develop some discussion about the weather over the life of the tree. The 1940s and 1950s were the best years for the silver maple!

Tree Cookies

I was in a class recently that included looking at some labelled tree cookies – for trees that are relatively common in our area. Each one is about a foot across. I photographed them to study on my large computer monitor.

Some of them have split as they dried and the saw marks are still visible…but the rings show through reasonably well. They would probably show up better if the cookies were sanded a little. There is something unique about each one: the sugar maple looks light colored throughout; the dogwood has wider dark marks (reddish in color) and they don’t appear to be concentric further away from the center); the cherry has a dark center; the white pine shows come places where branches come off and this cookie has the most clearly visible rings all the way out. It is possible to count the rings out from the center to determine the age of the tree when it was cut done.