The South Dakota Register of Big Trees is a list of the largest reported specimens of tree species found in the state, both native and naturalized. The primary purpose of the Register is to recognize big trees as a valuable natural resource worthy of conservation. Once identified and located, big trees may provide sources for superior seed collection and/or vegetative propagation. Through the Register of Big Trees, uncommonly large trees of any species, especially those with historical significance, are located and recorded. The owners and/or locators (nominators) of such trees are recognized through local and statewide news releases and special certificates.
The South Dakota Register of Big Trees recognizes champions in 57 different species. A total of 234 trees, both champions and challengers, are currently listed on the Register.
How are tree sizes compared?
Trees are compared in overall size by using a combination of three measurements. Each tree’s trunk circumference in inches is added to the height in feet plus one quarter of its crown spread in feet. The tree’s total point score is used to determine whether the tree is a champion. If the nominee has more points than the registered champion, then it becomes the new champion.
Nominees which do not qualify as state champions, but meet minimum circumference requirements, are classified as Challenger Trees, and are still registered as big trees. Should something happen to the reigning title holder, the list of challenger trees will be consulted to select the new champion.
South Dakota’s Largest Tree
South Dakota’s largest tree has always been a cottonwood. The current largest cottonwood is located along a fence line about 2 miles from the Missouri River, in rural Charles Mix County. It is 27 feet in circumference, 133 feet tall, and 122 feet in crown spread which results in a point score of 488.
How are big trees nominated?
An official nomination form can be requested through the South Dakota Department of Agriculture’s Resource Conservation and Forestry Division, 523 East Capitol Ave., Pierre, SD 57501-3182, or by calling 605-773-3623. A forester can be requested to measure and document the required information needed to challenge a spot on the big tree register.
How do I measure a big tree?
For the purposes of the Big Tree Register, a tree is defined as a woody plant having one erect perennial stem or trunk at least 9 1/2 inches in circumference at a point 4 1/2 feet above the ground, a definitely formed crown of foliage, and a height of at least 12 feet. If several stems from a single root system have grown together to form a trunk, only the largest stem can be considered.
Three measurements are required:
- Trunk circumference in feet and inches,
- Vertical to the nearest foot, and
- Average crown spread to the nearest foot.
Trunk circumference is measured at a point 4 1/2 feet above the center of the base of the tree. If the tree forks at 4 1/2 feet, measure the smallest circumference below that height. If it branches below 4 1/2 feet, measure the largest single stem at 4 1/2 feet.
The total height of the tree is considered to be the vertical distance between a horizontal plane passing through the center of the base of the tree and a horizontal plane passing through the top-most twig of the tree. The most accurate measurements of a tree’s height are made with standard measuring tools such as the Abney hand level, Forest Service hypsometer, a transit or other instrument. If such an instrument is unavailable, a straight stick can be used to obtain a fairly accurate height measurement.
Hold the stick at its base vertically at arm’s length making certain that the length of the stick above your hand equals the distance from your hand to your eye. Walk backwards away from the tree, staying on ground approximately level with the tree’s base. When the stick above your hand appears to be the same length as the tree, stop. You should be sighting over your hand to the base of the tree and, without moving anything but your eye, sighting over the top of the stick to the top of the tree. Measure how far you have backed away from the tree with a tape measure; a 100′ tape works best. That measurement should equate to the tree’s height.