Unit 2
How do foresters know how healthy a forest is? In this unit, you’ll learn the science of measuring trees and forests — from DBH (diameter at breast height) to tree height, crown ratio, and carbon storage. You’ll discover how foresters use these measurements to make informed management decisions, like when to thin a forest, how much carbon it stores, and how to plan for sustainable harvests.
Let's get started!
Unit 2 - Lesson 1
Tree Measurements and Tools
Let's get started!
Lesson 1: Introduction
Trees are integral components of ecosystems, impacting biodiversity, soil health, and water cycles. By learning to measure trees, we gain insights into their overall health and contribute to preserving the balance of ecosystems. In this lesson, we'll explore the practical side of things, exploring the tools and techniques used by foresters to measure trees. While there are tools to make measurements more efficient, every forester should know how to take measurements in the old-fashioned way, with math!
Before we jump in, let's go over a few new terms:
A tool used to measure angles, which can be used to calculate tree height.
A standard measurement for trees, taken at 4.5 ft (1.4 m) above the ground.
The leafy or needle-covered branches of a tree.
The distance around a circular object, like a tree trunk.
Diameter at Breast Height (DBH)
Title
Title
Title
Title
Circumference
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Clinometer
Foliage
Subtitle
Subtitle
Subtitle
Subtitle
The distance from the base of the tree to its top.
A tool that extracts a narrow core sample from a tree to estimate age and growth rate.
The upper part of a tree that contains foliage; acts as the tree’s “solar panel.”
The percentage of a tree’s total height that contains living foliage.
Live Crown Ratio (LCR)
Title
Title
Title
Title
Tree Height
Increment Borer
Crown
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Subtitle
Subtitle
Subtitle
Subtitle
How do you measure a tree?
Before we actually mesure any trees, we need to learn about the terms and tools foresters use!
Diameter at Breast Height (DBH)
Diameter at Breast Height (DBH) is the standardized, universally accepted way to measure the diameter of a tree. It’s taken at 4.5 feet (1.4 meters) above the ground to ensure consistency when comparing trees of different sizes and species.
These are some of the tools foresters use to calculate DBH:
By measuring the DBH of many trees in a forest stand, foresters can better understand the structure and composition of the forest. This information helps them make informed decisions about thinning, harvesting, and regeneration. DBH data is also used to group trees into age classes and monitor how a forest changes over time.
This video from The Timberland Investor explains how to measure DBH properly!
So now we've learned how to measure a tree, but what if...
...the tree is has a split?
...the tree is leaning?
...the tree is has multiple stems?
Tree height
This mesurement can tell us a lot about a forest!
This information is crucial for timber inventory and management, helping foresters plan sustainable harvesting practices and calculate potential wood yields.
These are some of the tools foresters use to calculate tree height:
Tree height also helps scientists understand how a forest works — how sunlight moves through the canopy, how trees compete for light, and how leaves and branches are spread out from the forest floor to the top of the trees.
Tree height calculations
So how do foresters use a clinometer?
UC Agriculture and Natural Resources, © Regents of the University of California.
You might not have a clinometer at home, but don't worry! Here are a few other options for measuring tree height:
This video from the Georgia Forestry Commission does a great job of explaining the methods foresters use to mesure trees. It also describes how you can calculate tree height using household items!
This video from Wilson Forest Lands explains how to estimate the height of a tree using the stick method.
Live crown ratio (LCR)
Knowing the hight of a tree can also help us measure the live crown ratio (LCR). LCR is the percentage of the tree’s total height that has live branches growing out of it.
The LCR is an important indicator of a tree's health
When the tallest trees (called dominant trees) have an LCR below 30–35%, it can mean the trees are crowded and not growing much because they’re competing too hard for sunlight and space.
When the dominant trees’ LCR is above 40–50%, it shows the trees likely have plenty of space, are getting enough light, and are growing strongly.
That was a lot of information! Let's answer some questions to see what you've learned:
Unit 2 - Lesson 2
Tree volume
Lesson 2: Introduction
We’ve learned that foresters use several key measurements—like DBH (diameter at breast height), tree height, and live crown ratio—to understand a forest. DBH and tree height can also be used to estimate how much wood a tree contains, which is measured in board feet.
A board foot is a unit used to describe wood volume. It represents a board that is one foot long, one foot wide, and one inch thick. Even though this measure comes from older milling practices, it’s still used today to estimate how much usable wood is in a tree or log. Modern sawmills are much more efficient than when this standard was created, so they can often produce about twice as much lumber from the same amount of logs—but foresters still use board feet because it’s the most common and consistent way to estimate a tree’s volume and value.
Let's take a moment to review some important vocabulary:
A volume unit of measure equal to the cubic contents of a piece of lumber one-foot square and one inch thick, used in measuring logs and lumber
A portion or length of the trunk or a large limb of a felled tree.
A log sawed or split into planks, boards, etc.
Lumber
Title
Board Foot
Title
Log
Title
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Use this side to give more information about a topic.
Subtitle
Subtitle
Subtitle
Equations for calculating volume in a table form for estimating. The most common for this region is the Scribner.
The amount of space a tree occupies.
Log scale table
Tree Volume
Title
Title
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Subtitle
Subtitle
How to Measure the Volume of Standing Trees
Video by Alabama Extension
Now, let's estimate volume and value!
Scribner Table
Take a look at the Scribner table. If you have have a Douglas-fir that is 85 feet tall, with a DBH of 16, what would the board foot volume be? What if it is 115 feet tall, with a DBH of 28?
Once you've identified the board foot volume, you can calculate the value!
Head to the Department of Natural Resources (DNR) Timber Sale Query/Log Prices page to find the most recent monthly log prices
WA DNR Timber Sale Query/Log Prices
Reflection
Take a few minutes to think about what you learned this lesson, and answer the following questions:
How did the tree value compare with your expectations?
What are some real-world scenarios where the knowledge of log volume could be applied, and how might it impact decision-making in the forestry industry?
Think about how logs are turned into lumber. Log diameter is measured on the small side – why is that?
Hint
Unit 1 - Lesson 3
Carbon Storage
Lesson 3: Introduction
Forests act as vast reservoirs for carbon, storing immense amounts of it in trees, soil, and other organic matter. Trees absorb carbon dioxide from the atmosphere through photosynthesis, utilizing it to produce energy while releasing oxygen as a byproduct. The ability of trees to sequester carbon plays an important role in reducing greenhouse gasses in the atmosphere. But how do we measure the amount of carbon stored in trees? This is where the science of forestry comes into play! Foresters employ various techniques like DBH and height measurements, biomass assessments, and advanced technologies to accurately quantify the carbon stored within forest ecosystems. Understanding the role of forests in carbon storage will allow us to understand how forest management can be used to adapt to our changing climate.
Let's go over a few new terms:
An element that forms organic compounds (linked to other elements such as Oxygen) that occurs in a pure state as diamond and graphite and in impure as charcoal.
A carbon/oxygen compound that is sent into the atmosphere and causes rising temperatures.
An environment's ability to absorb carbon dioxide from the atmosphere.
Total intake of carbon over a period of time.
Carbon sequestration
Title
Title
Title
Title
Carcon
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Carbon dioxide
Carbon sink
Subtitle
Subtitle
Subtitle
Subtitle
The amount of carbon that exists in a tree’s leaves, wood, stem, roots, and bark at a particular point in time.
An estimate of the mass of a tree when it is alive, including wood and moisture.
The mass of wood when moisture is removed.
Title
Title
Title
Dry weight
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Stored Carbon
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Green weight
Subtitle
Subtitle
Subtitle
Calculating the Carbon in Trees
Green Weight (GW) is an estimate of the mass of a tree when it is alive. This includes wood and moisture and uses an average constant to represent a region broadly, not an individual tree. GW (metric tons) = .2 x DBH (inches)2 x height (feet).
Carbon Storage = DW x .5.
This is carbon captured from the atmosphere during photosynthesis and sequestered by the tree over time. This will tell you how much carbon is stored over time!
Dry Weight (DW), which represents the mass of the wood in the tree when moisture is removed. DW = GW x .5
You can also take a look at this detailed worksheet from Trees of the Future
Trees for the Future Worksheet: How to calculate the amount of CO2 sequestered in a tree per year
Carbon in Context
What is a carbon footprint?
A carbon footprint measures the total greenhouse gas emissions — primarily CO₂ — generated by an individual, organization, or product. It includes both direct emissions (like driving a car) and indirect ones (like producing food or power).
What a carbon footprint is and how it’s calculated The biggest sources of carbon emissions The role of forests in absorbing carbon How to estimate your own carbon footprint Why systemic change is needed beyond personal actions
The article covers:
Look through this Forest Stewardship Council (FSC) article (linked below) to learn more.
What is a carbon footprint? Explore its history and why it matters.
Unit 2 - Conclusion
Congradulation! You’ve learned how foresters collect data that guides real-world decisions about forest management. By measuring trees and calculating things like biomass and carbon storage, you’ve seen how science connects to sustainability — helping balance forest health, wildlife habitat, and resource use.
Now, on to Unit 3!
If the tree is leaning...
When a tree trunk grows on a slope or leans to one side, you measure 4.5 feet along the trunk itself, following its center line. Then, take measurements on both the shorter side (uphill) and the longer side (downhill) of the trunk, and use the average of those two numbers as your height.
Wrap your diameter or circumference tape perpendicular (at a right angle) to the trunk’s center line — not simply horizontal to the ground.
Diameter at Breast Height
To measure DBH, first measure the circumference of the tree — the distance around its trunk at 4.5 feet above the ground. Then, divide that number by 3.14 (π) to find the diameter.
Formula: DBH = Circumference ÷ 3.14
This video from Wilson Forest Lands explains how to estimate the height of a tree using a stick and optional tape measure!
This video from the Georgia Forestry Commission explains the tools foresters use to mesure trees, and describes how you can calculate tree height using household items.
TIf the tree has multiple trunks, measure each of the trunks, and then add the total diameter of the largest trunk to one-half the diameter of each additional trunk
If the tree has a split, measure the smallest circumference below the lowest branch
How to calculate tree height
The math for calculating tree height uses: The angle to the top of the tree, distance from the tree, and eye height.
Unit 2
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Transcript
Unit 2
How do foresters know how healthy a forest is? In this unit, you’ll learn the science of measuring trees and forests — from DBH (diameter at breast height) to tree height, crown ratio, and carbon storage. You’ll discover how foresters use these measurements to make informed management decisions, like when to thin a forest, how much carbon it stores, and how to plan for sustainable harvests.
Let's get started!
Unit 2 - Lesson 1
Tree Measurements and Tools
Let's get started!
Lesson 1: Introduction
Trees are integral components of ecosystems, impacting biodiversity, soil health, and water cycles. By learning to measure trees, we gain insights into their overall health and contribute to preserving the balance of ecosystems. In this lesson, we'll explore the practical side of things, exploring the tools and techniques used by foresters to measure trees. While there are tools to make measurements more efficient, every forester should know how to take measurements in the old-fashioned way, with math!
Before we jump in, let's go over a few new terms:
A tool used to measure angles, which can be used to calculate tree height.
A standard measurement for trees, taken at 4.5 ft (1.4 m) above the ground.
The leafy or needle-covered branches of a tree.
The distance around a circular object, like a tree trunk.
Diameter at Breast Height (DBH)
Title
Title
Title
Title
Circumference
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Clinometer
Foliage
Subtitle
Subtitle
Subtitle
Subtitle
The distance from the base of the tree to its top.
A tool that extracts a narrow core sample from a tree to estimate age and growth rate.
The upper part of a tree that contains foliage; acts as the tree’s “solar panel.”
The percentage of a tree’s total height that contains living foliage.
Live Crown Ratio (LCR)
Title
Title
Title
Title
Tree Height
Increment Borer
Crown
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Subtitle
Subtitle
Subtitle
Subtitle
How do you measure a tree?
Before we actually mesure any trees, we need to learn about the terms and tools foresters use!
Diameter at Breast Height (DBH)
Diameter at Breast Height (DBH) is the standardized, universally accepted way to measure the diameter of a tree. It’s taken at 4.5 feet (1.4 meters) above the ground to ensure consistency when comparing trees of different sizes and species.
These are some of the tools foresters use to calculate DBH:
By measuring the DBH of many trees in a forest stand, foresters can better understand the structure and composition of the forest. This information helps them make informed decisions about thinning, harvesting, and regeneration. DBH data is also used to group trees into age classes and monitor how a forest changes over time.
This video from The Timberland Investor explains how to measure DBH properly!
So now we've learned how to measure a tree, but what if...
...the tree is has a split?
...the tree is leaning?
...the tree is has multiple stems?
Tree height
This mesurement can tell us a lot about a forest!
This information is crucial for timber inventory and management, helping foresters plan sustainable harvesting practices and calculate potential wood yields.
These are some of the tools foresters use to calculate tree height:
Tree height also helps scientists understand how a forest works — how sunlight moves through the canopy, how trees compete for light, and how leaves and branches are spread out from the forest floor to the top of the trees.
Tree height calculations
So how do foresters use a clinometer?
UC Agriculture and Natural Resources, © Regents of the University of California.
You might not have a clinometer at home, but don't worry! Here are a few other options for measuring tree height:
This video from the Georgia Forestry Commission does a great job of explaining the methods foresters use to mesure trees. It also describes how you can calculate tree height using household items!
This video from Wilson Forest Lands explains how to estimate the height of a tree using the stick method.
Live crown ratio (LCR)
Knowing the hight of a tree can also help us measure the live crown ratio (LCR). LCR is the percentage of the tree’s total height that has live branches growing out of it.
The LCR is an important indicator of a tree's health
When the tallest trees (called dominant trees) have an LCR below 30–35%, it can mean the trees are crowded and not growing much because they’re competing too hard for sunlight and space.
When the dominant trees’ LCR is above 40–50%, it shows the trees likely have plenty of space, are getting enough light, and are growing strongly.
That was a lot of information! Let's answer some questions to see what you've learned:
Unit 2 - Lesson 2
Tree volume
Lesson 2: Introduction
We’ve learned that foresters use several key measurements—like DBH (diameter at breast height), tree height, and live crown ratio—to understand a forest. DBH and tree height can also be used to estimate how much wood a tree contains, which is measured in board feet.
A board foot is a unit used to describe wood volume. It represents a board that is one foot long, one foot wide, and one inch thick. Even though this measure comes from older milling practices, it’s still used today to estimate how much usable wood is in a tree or log. Modern sawmills are much more efficient than when this standard was created, so they can often produce about twice as much lumber from the same amount of logs—but foresters still use board feet because it’s the most common and consistent way to estimate a tree’s volume and value.
Let's take a moment to review some important vocabulary:
A volume unit of measure equal to the cubic contents of a piece of lumber one-foot square and one inch thick, used in measuring logs and lumber
A portion or length of the trunk or a large limb of a felled tree.
A log sawed or split into planks, boards, etc.
Lumber
Title
Board Foot
Title
Log
Title
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Subtitle
Subtitle
Subtitle
Equations for calculating volume in a table form for estimating. The most common for this region is the Scribner.
The amount of space a tree occupies.
Log scale table
Tree Volume
Title
Title
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Subtitle
Subtitle
How to Measure the Volume of Standing Trees
Video by Alabama Extension
Now, let's estimate volume and value!
Scribner Table
Take a look at the Scribner table. If you have have a Douglas-fir that is 85 feet tall, with a DBH of 16, what would the board foot volume be? What if it is 115 feet tall, with a DBH of 28?
Once you've identified the board foot volume, you can calculate the value!
Head to the Department of Natural Resources (DNR) Timber Sale Query/Log Prices page to find the most recent monthly log prices
WA DNR Timber Sale Query/Log Prices
Reflection
Take a few minutes to think about what you learned this lesson, and answer the following questions:
How did the tree value compare with your expectations?
What are some real-world scenarios where the knowledge of log volume could be applied, and how might it impact decision-making in the forestry industry?
Think about how logs are turned into lumber. Log diameter is measured on the small side – why is that?
Hint
Unit 1 - Lesson 3
Carbon Storage
Lesson 3: Introduction
Forests act as vast reservoirs for carbon, storing immense amounts of it in trees, soil, and other organic matter. Trees absorb carbon dioxide from the atmosphere through photosynthesis, utilizing it to produce energy while releasing oxygen as a byproduct. The ability of trees to sequester carbon plays an important role in reducing greenhouse gasses in the atmosphere. But how do we measure the amount of carbon stored in trees? This is where the science of forestry comes into play! Foresters employ various techniques like DBH and height measurements, biomass assessments, and advanced technologies to accurately quantify the carbon stored within forest ecosystems. Understanding the role of forests in carbon storage will allow us to understand how forest management can be used to adapt to our changing climate.
Let's go over a few new terms:
An element that forms organic compounds (linked to other elements such as Oxygen) that occurs in a pure state as diamond and graphite and in impure as charcoal.
A carbon/oxygen compound that is sent into the atmosphere and causes rising temperatures.
An environment's ability to absorb carbon dioxide from the atmosphere.
Total intake of carbon over a period of time.
Carbon sequestration
Title
Title
Title
Title
Carcon
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Carbon dioxide
Carbon sink
Subtitle
Subtitle
Subtitle
Subtitle
The amount of carbon that exists in a tree’s leaves, wood, stem, roots, and bark at a particular point in time.
An estimate of the mass of a tree when it is alive, including wood and moisture.
The mass of wood when moisture is removed.
Title
Title
Title
Dry weight
Use this side to give more information about a topic.
Stored Carbon
Use this side to give more information about a topic.
Use this side to give more information about a topic.
Green weight
Subtitle
Subtitle
Subtitle
Calculating the Carbon in Trees
Green Weight (GW) is an estimate of the mass of a tree when it is alive. This includes wood and moisture and uses an average constant to represent a region broadly, not an individual tree. GW (metric tons) = .2 x DBH (inches)2 x height (feet).
Carbon Storage = DW x .5.
This is carbon captured from the atmosphere during photosynthesis and sequestered by the tree over time. This will tell you how much carbon is stored over time!
Dry Weight (DW), which represents the mass of the wood in the tree when moisture is removed. DW = GW x .5
You can also take a look at this detailed worksheet from Trees of the Future
Trees for the Future Worksheet: How to calculate the amount of CO2 sequestered in a tree per year
Carbon in Context
What is a carbon footprint?
A carbon footprint measures the total greenhouse gas emissions — primarily CO₂ — generated by an individual, organization, or product. It includes both direct emissions (like driving a car) and indirect ones (like producing food or power).
What a carbon footprint is and how it’s calculated The biggest sources of carbon emissions The role of forests in absorbing carbon How to estimate your own carbon footprint Why systemic change is needed beyond personal actions
The article covers:
Look through this Forest Stewardship Council (FSC) article (linked below) to learn more.
What is a carbon footprint? Explore its history and why it matters.
Unit 2 - Conclusion
Congradulation! You’ve learned how foresters collect data that guides real-world decisions about forest management. By measuring trees and calculating things like biomass and carbon storage, you’ve seen how science connects to sustainability — helping balance forest health, wildlife habitat, and resource use.
Now, on to Unit 3!
If the tree is leaning...
When a tree trunk grows on a slope or leans to one side, you measure 4.5 feet along the trunk itself, following its center line. Then, take measurements on both the shorter side (uphill) and the longer side (downhill) of the trunk, and use the average of those two numbers as your height.
Wrap your diameter or circumference tape perpendicular (at a right angle) to the trunk’s center line — not simply horizontal to the ground.
Diameter at Breast Height
To measure DBH, first measure the circumference of the tree — the distance around its trunk at 4.5 feet above the ground. Then, divide that number by 3.14 (π) to find the diameter.
Formula: DBH = Circumference ÷ 3.14
This video from Wilson Forest Lands explains how to estimate the height of a tree using a stick and optional tape measure!
This video from the Georgia Forestry Commission explains the tools foresters use to mesure trees, and describes how you can calculate tree height using household items.
TIf the tree has multiple trunks, measure each of the trunks, and then add the total diameter of the largest trunk to one-half the diameter of each additional trunk
If the tree has a split, measure the smallest circumference below the lowest branch
How to calculate tree height
The math for calculating tree height uses: The angle to the top of the tree, distance from the tree, and eye height.