1. What species are eligible for the National Register of Big Trees?
2. How are species added to the Register's species list?
3. What is a native or naturalized tree?
4. What is a tree vs. shrub?
5. How do you determine a National Champion?
6. How do I nominate a tree?
7. How do I identify and measure my tree?
8. Do states have their own Big Tree Register's?
9. Can I visit a National Champion? If so, how can I found out where they are located?
10. My tree is on an extremely steep slope. How can I measure its circumference?
11. My tree has a canker or branch at 4 1/2 feet. Where is circumference measured?
12. How do I determine if a tree is one tree or multiple trees?
13. Is circumference measured at 4 1/2 feet above the ground or 4½ feet along the trunk?
14. How do I measure a palm tree?
15. How far is too far-gone?
16. What is an epicormic sprout?
17. How do I measure Height using a Clinometer?

General Questions:

What species are eligible for the National Register of Big Trees?

To be eligible for the National Register of Big Trees, a species must be recognized as native or naturalized in the continental United States, including Alaska but not Hawaii. (Species found only in Hawaii are not included.) Hybrids and minor varieties are excluded. There are 826 eligible species and varieties: 747 native and 79 naturalized. To determine eligibility, American Forests uses Elbert L. Little Jr.'s Checklist of United States Trees (Native and Naturalized), published in 1979 as U.S. Department of Agriculture Agricultural Handbook 541.

To find out if your tree species is eligible, Search the Register and type in the common or scientific name. You can double check by scrolling through the Register.

How are species added to the Register's species list?

Additions to the species list for the American Forests National Register of Big Trees should be submitted with supporting materials to American Forests for review by the Big Tree Committee by January 1st of every odd year. New species editions will be evaluated by both the committee and experts and added to the official species list no later than April 1st.

What is a native or naturalized tree?

Native tree species (also called indigenous) are wild and grew naturally or spontaneously in the undisturbed forest vegetation before the arrival of Columbus or other Europeans.

Introduced tree species have been brought into the United States. A naturalized tree is an introduced species that has become common and established itself as though wild, reproducing naturally and spreading.

What is a tree vs. shrub?

As defined in the Checklist, trees are woody plants with one erect perennial stem or trunk at least 9 ½ inches in circumference (3 inches in diameter) at 4 ½ feet above the ground (breast height), a definitely formed crown of foliage, and a height of at least 13 feet. In contrast, shrubs are small woody plants, usually with several perennial stems branching at the base.

How do you determine a National Champion?

American Forests uses the following calculation to determine a tree's total points:
Trunk Circumference (in inches) + Height (in feet) + ¼ Average Crown Spread (in feet) = Total Points

A nominee will replace a registered champion if it has more points. When two trees have scores that fall within 5 points of each other, they are listed as co-champions.

Champions must be remeasured within 10 years of the current Register to maintain their Champion status. For example, national champions last measured before 1998 must be remeasured for the 2008 register to remain champions.

How do I nominate a tree?

You can do so online or download our nomination form.

How do I identify and measure my tree?

Our Big Tree Measuring Guide gives some useful measuring tips. However, if your still scraching your head, help is at hand. The state Big Tree Coordinators can also help you identify and measure your tree.

Do states have their own Big Tree Register's?

Many states have their own Registers which list state Champions. To find out if your state has a program, look under State Registers or contact your state Big Tree Coordinators.

Can I visit a National Champion? If so, how can I found out where they are located?

Many of our Champions are located on public land (such as national forests, national or state parks) and can be visited without a problem. If a tree is located on private land, we ask that you respect the private landowner and ask permission before making a visit.

Measuring Questions:

When measuring a tree you may encounter some unexpected challenges. As a continuation of our Big Tree Measuring Guide, this section looks at some challenges that may arise when measuring your tree.

Measuring circumference from the mid-point of the trunk.

My tree is on an extremely steep slope. How can I measure its circumference?

When measuring the circumference of a tree on a slope, measurements are normally taken at the high and low side of the slope and then averaged. However, in some cases an especially steep slope may prevent the low side of the trunk from being measured. In this situation, the measurement should be taken at 4 ½ feet above the mid-point of the trunk.

My tree has a canker or branch at 4 1/2 feet. Where is circumference measured?

If there is a growth or branch on the trunk at 4 1/2 ft, measure the smallest point below 4 1/2 ft.

How do I determine if a tree is one tree or multiple trees?

In order to properly measure circumference, it must be determined whether the tree in question has a single trunk that can be measured or whether it represents two or more trees growing very close to one another. Trunks that have clear separation at or near the ground should be considered separate trees and measured accordingly. Also if the circumference measurement below the lowest fork places the measurement at the ground, it should be considered separate trees.

Is circumference measured at 4 1/2 feet above the ground or 4½ feet along the trunk?

Measure 4½ feet from where the tree enters the ground along the axis of the tree, as shown in the illustration at right.

How do I measure a palm tree?

When measuring a palm tree, include foliage (fronds and leaves) into the height and average crown spread. For circumference, trunk measurements should not include thatch or dead leaves.

Do height and average crown spread measurements include dead parts of the tree?

Measurements for height and average crown spread incorporate all parts of the tree, dead or alive. If part of the tree appears to be in danger of falling off, make a note of it on the nomination form.

How far is too far-gone?

A tree is eligible as long as it is rooted and technically still alive. If you are concerned about a tree's condition, make a note of it on the nomination form.

What is an epicormic sprout?

If the tree forks record in inches the smallest circumference between 4½ feet and the ground below the lowest fork excluding dead branches and epicormic sprouts.

How do I measure height using a Clinometer?

This procedure requires that the measurer have a clinometer with a % slope scale. The measurer moves back to a point where the top of the tree is directly visible. For trees over 100 feet tall possessing broad crowns, this distance will usually be 150 feet or more. Using the clinometer, the spot on the trunk that is at eye level is identified and the distance from the eye to the level point on the trunk is measured with a tape or laser rangefinder. Using the clinometer, the percent slope to the top of the tree is obtained followed by the percent slope to the base of the tree.

The % slope associated with the top of the tree is then multiplied by the level distance to the trunk to get the height of the tree above eye level. The procedure is repeated for the base of the tree to get the height between eye level and the base of the tree. If the base of the tree is below eye level, the two heights are added to get the total tree height. If the eye is below the base of the tree, the eye to base height is subtracted from the eye to top of crown height to get actual tree height. This method assumes that the top of the crown is directly over the base of the tree. Note that if the user doesn't have a laser to measure the eye level distance to the trunk, this method requires that the user measure the tree from approximately the same contour.