# How do you measure the size of a tree?

Take a measurement around the tree's trunk four and a half feet (4.5') above the ground on the tree's uphill side (if not on even ground). If the tree forks or bulges below 4.5', take a circumference measurement when the tree achieves normal size or tapers below the 4.5' foot mark. Use a string and ruler to record your measurements.

Here are some more detailed answers to questions that may arise when measuring a tree:

Why must you measure a tree from the outside in? The inside of a tree is called the "bark". You should always measure the outer part of the tree because that is where most people see its health from. The inner part of the tree is called the "trunk" or "crown". That is how people know if the tree is growing tall or not. A small inner trunk indicates that the tree is young and growing; however, it can also indicate that the tree is too small for its location. An older tree with no signs of life beyond browning bark should be removed by a professional tree surgeon.

Why must you measure a tree three times and average these numbers? It is important to remember that trees grow differently so they will never have exactly the same size trunk. Measurements will vary slightly depending on which part of the tree is being measured and whether it is day or night. By taking multiple measurements over time, we can come up with an accurate estimate of the overall growth of the tree.

## How tall does a tree have to be to fall over a back lean?

Before the tree falls, the weight of the tree must be transferred across this pivot point. The back lean of the 60-foot-tall tree to the right is three feet. Then, measure the diameter of the stump from the front of the hinge to the rear edge of the tree (see illustration). If the diameter is less than 30 inches, then the tree will not fall over due to load capacity. If the diameter is greater than 30 inches, then the tree could fall over backward.

The reason for this is because trees with trunks larger than 30 inches in diameter are likely to have been hit by lightning, which means they're dead trees. The load of living trees is distributed along the whole trunk, so it's very unlikely that any one branch or section of a branch is strong enough to hold such a weight.

However, even large dead trees can fall over if an important branch is broken off. For example, if a huge dead tree stands in the middle of a forest and its branch has been broken off about 15 feet above the ground, then animals may use that branch as a bridge between trees, forming a walkway down which they travel from tree to tree. In this case, the broken branch might be used by some unknown creature.

Trees fall over for many different reasons.

## What is the diameter of a tree trunk?

On big trees, trunk diameter is measured at "breast height," which is 4-1/2 feet above ground, and is also known as DBH, or Diameter Breast Height. To determine the DBH, stand close to the tree's trunk and measure 4.5 feet above the ground. Most large trees have their own name for this height, such as "knee high" or "head high."

On small trees, trunk diameter is usually measured at the base of a large branch, 1.7 times the diameter of the branch itself. This is called the bole diameter. To determine the bole diameter, stand with one foot on either side of the tree and measure the distance between the outer edges of your feet. This will give you the total bole diameter.

Some species of trees have trunks that are hollow inside. Such trees are called "trees of any size." Examples include American beech, black cherry, cottonwood, elm, sycamore, and white oak.

Trees can get very large. The largest living trees on Earth are sequoia sempervirens and titan arum. Sequoia is derived from the Latin word for "evergreen," because its leaves remain green all year long. Titan arum has been estimated to be over 300 years old!

## How do you measure the height of a tree for kids?

Move backwards or forwards such that the top of the tree is just visible between your legs. The distance between your feet and the tree trunk should be measured. The distance between your feet and the trunk is approximately the same height as the tree when you can see the top of the tree between your legs. This is how tall the tree is.

This method works best if you have an open area where you can walk without being in someone's garden. If you're lucky enough to have access to a crane then great, but not everyone does. When measuring tree heights it's important to remember that the lower branches will tend to lean away from the trunk which will make their length appear shorter than it actually is.

For example, if a small branch is bent over at a 90-degree angle to the main trunk but its end is 1 foot away from the main branch then it is 1 foot high. The actual distance between the two branches is 1 foot less than what appears. This technique can be used for most trees, but it's easier to estimate the height of large trees because there are more branches and thus more ways to overestimate height.

Trees grow through growth rings. Each year the tree grows down into its own body weight in order to sustain itself. At the end of each season the tree stops growing and enters a rest period during which it builds up energy for the next growing season.

##### Marian Hargrove

Marian Hargrove is a teacher who has been in the education field for over 10 years. Marian is passionate about helping her students reach their full potential and strives to make learning fun and interesting for all of her pupils. She graduated from the University of New Mexico with a Bachelor's degree in Elementary Education.

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