How to study a tree: a Macoun Field Club example

Photo of 14-inch diameter Bitternut Hickory

A study tree is one that you go back to again and again, and observe closely. It is an individual living thing, and as time goes on, you learn more and more of its life story. Dramatic things can happen, but more often you’re trying to interpret puzzling patterns and shapes long after the event that caused them. You discover that the lives of many other plants and animals are connected to your tree, and it is possible that some of them will become far more interesting to you than what you started with.

Photo of Sapsucker-caused raised ring on Bitternut Hickory

At left, for instance, is a Bitternut Hickory in our special study-tree woods, which has a dozen horizontal, ring-like markings at intervals up the trunk, starting at eye-level. Many explanations have been offered for rings like this, but no one we know has actually seen what made them, so we have to observe the evidence, and think about it.

Each ring is actually a rough groove in the crest of a swollen ridge. The swelling of the trunk tells you that the origin of the ring is many years in the past, because even in reaction to injury, the wood under the bark grows slowly. In fact, we know from our own observations of this particular tree that these rings look pretty much the same now as they did ten years ago.

Photo of Sapsucker-caused raised-ring on Bitternut Hickory - detail

Closer examination reveals two further clues. First, as shown at right, there is a series of small woody bumps in the bottom of the furrow. Second, some of these woody plugs have been chipped out fairly recently, leaving small holes about 4 mm across, and not much deeper. Elsewhere on the trunk are lines of the woody plugs that have not been removed, where there is no swelling of the trunk.

The furrow is not continuous, so the mark isn’t that of a beetle cutting a groove horizontally under the bark, and also it isn’t quite straight. Both points rule out damage from a wire tied around the trunk. Furthermore, the little holes don’t go in very far, so they weren’t left by wood-boring beetles. Squirrels, which like sap, might nibble the pegs off, but wouldn’t be able to bite out holes like these. But there is an animal that does drill shallow little holes in tree bark, often in more or less straight lines — the Yellow-bellied Sapsucker. Like humans tapping maples in a sugar bush, this bird taps trees and drinks the sap.

Each small woody plug is the tree’s response to a tiny injury, and it becomes part of the bark where it is left alone. But if a Sapsucker should come back year after year, and remove many of the plugs as the easiest way of opening up the bark again, the tree would be continually irritated. Its response to this repeated, more extensive damage appears to be extra growth in the affected area — a permanent swelling, under a break in the bark.

If this were your study tree, you would have discovered a long-term connection to a unique species of bird, and through that bird to dozens of other sap-drinking creatures, from bees and butterflies to hummingbirds.

Why you do it

Choosing your own study tree gives you something real and personal in the bewilderingly varied world of nature. Until you do, all trees in the forest seem to look pretty much alike. But afterward, you start to recognize the particular shape of your tree, and soon can tell it apart from every other tree in the forest.

Finding your way back to the same tree lets you see how events affect it, and gives you first-hand experience in reading the evidence of similar changes that happened on other trees many years before. Scrapes and scratches, and wounds you never would have noticed before come to have meaning, and when you see them on other trees, they tell you their story too. You will gain a reputation for being able to interpret the signs of nature.

Where do you begin?

Photo of Macoun Club member Sarah Potvin with her White Ash seedling

You start by picking a tree that catches your eye, in a place where you will be able to find it again. It can even be right in your front yard! But in the Macoun Club, we have selected a particular forest in the western Greenbelt as our study site. There, the field-trip leaders will take special note of your choice, and guide you back on your next visit. See what we learn from our visits, and how things work out in the long run.

Next, you take a long hard look at the tree, and notice things about it. One obvious item is the tree’s identity — what species is it? And is it actually alive? (a dead tree can be an especially good choice!). There are measurements to make and features to note. You will probably have to guess the tree’s age, but by considering the clues, you can make an educated guess.

Finally, you will want to make note of what else is on or in your tree. Does it have a bird’s nest in it? Are there lichens and mosses living on the trunk? Has something been eating it?

How far can you go?

Certainly you will become the world’s expert on your own study tree. No one else will have looked at it as often or as thoroughly as you. Your tree also represents its species, and if it has excited your interest, you will come to know a great deal about that, too — when it produces seeds, how old it can be, what it is used for, by wild animals and human beings. The same can be said for anything connected with your tree. It is up to you how far you pursue knowledge.

Photo of Large-toothed Aspen in 1992

Most people think that the answers to every question can be looked up in a book, or found by browsing the internet. But the truth is that by looking long and hard at a real living thing in nature, you will very soon come to the end of what is known, and be discovering things not yet written in any book. This has happened before in the Macoun Club.

Where the Macoun Club’s study trees are

All official Macoun Club study trees are located in a forest in Ottawa’s western Greenbelt. You can see where on our map. This is federal conservation land, and the trees are protected.

All photos donated or provided by members and leaders, past and present. Created Sept. 30, 2004. Coding revised in May, 2016.