Native Tree Society

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The Native Tree Society (NTS) (formerly the Eastern Native Tree Society, ENTS) is not-for-profit Internet interest group formally established in 1996 to celebrate trees in the arts, science, mythology, medicine, and related areas. Present NTS membership is around 250.

Tree measurement[edit]

An important mission of NTS is to develop advanced field techniques for measuring trees and maintaining a database of outstanding trees and sites within the eastern forest type. NTS is considered[by whom?] to be the premier tree measuring organization in the eastern United States and holds annual workshops on tree measuring. The workshops concentrate on methods for measuring tree height, girth, crown spread, trunk and limb volume. At workshops, different height methods are demonstrated and compared. The workshops are held periodically in Mohawk Trail State Forest, Massachusetts and Cook Forest State Park, Pennsylvania.

A small elite group of NTS members headed by Will Blozan climb important trees to measure their heights by the method of dropping a tape from the top of the tree down to the base to get a highly accurate measurement. Trigonometry based methods are then compared with the results of tape drops. The vast majority of trees are measured using a combination of lasers, hypsometers, and trigonometry. Accuracies for tree heights measured through trigonometry are generally within ±1.0 feet. However, accuracies to within ±0.5 foot are regularly obtained when statistics are applied, and can be within ±0.25 foot. It is this high level of accuracy that distinguishes NTS tree measuring methods from other approaches. Bragg et al. (2011) report on the methodology:

"The sine method provides direct (not extrapolated) measurements of observed points on the tree, thereby generating tree height as the elevation difference between two horizontal planes. This geometric translation of a three-dimensional object thereby eliminates the need to conduct ad hoc adjustments for tree lean, offset crown high points, and ground slope in the field...its accuracy, reliability, and repeatability suggest that it can be considered a standard for any science-based studies of forest conditions that include height as a parameter."[1]

Founders and officers[edit]

The cofounders of NTS include Robert T. Leverett, Will Blozan, Dr. David Stahle, the late Dr. Michael Perlman, and Dr. Matthew Therrell. Edward Frank maintains the website and the BBS discussion list of NTS. Information available at those pages is available for use in scientific research with permission from one of the officers. The present officers of NTS are Will Blozan, President; Dr. Lee Frelich, Vice President; and Robert Leverett, Executive Director. Dr. Don C. Bragg is the editor of the Bulletin of the Eastern Native Tree Society.[2] Edward Frank is the editor of the eNTS Magazine, a monthly summary of the posts made to the NTS BBS.[3]

The organization changed its name to the Native Tree Society in July 2011 to reflect a broader membership across the United States, Canada, and elsewhere in the world. The name Eastern Native Tree Society was retained for the original chapter of the organization encompassing eastern North America.[4]


The organization presently devotes much of its time to scientific research associated with determining the maximum sizes and ages to which trees, by species, grow in the eastern United States, locally, regionally, and range wide. NTS also makes itself available to other organizations in resolving disputes over tree dimensions, particularly tree heights.

NTS is involved with the identification and documentation for historical purposes of old growth forest sites. Detailed site descriptions are maintained at the NTS website. NTS routinely uses an important, numerically based, type of comparative site documentation. The documentation is formally called Rucker Analysis. One of more indices are computed for each site. Collectively, these indices reveal girth and height patterns for the included species.

Key NTS members are noted old growth forest researchers. NTS members help identify potential new old growth sites. Managing for old growth characteristics is a research interest of NTS.


Some noteworthy accomplishments of NTS include the engineering of tree height measurement techniques that utilize sine-based mathematics. This approach eliminates the often sizable errors associated with the popular percent slope method or tangent-based mathematics. NTS has also engineered field-based volume measurement techniques for modeling the trunks of trees. By dividing the trunk into sections and applying geometric solids, principally conoid, paraboloid, and neiloid forms, trunk volume can be measured to within ±5.0% of the water displacement volume. These are called form factors. Cross-sectional areas are usually treated as circular or elliptical. The zone where a tree trunk divides into two or more trunks is handled through a special technique that takes into account shapes that cannot otherwise easily be modeled.

NTS is in the process of establishing the discipline of dendromorphometry, a term coined by Professor Gary Beluzo of Holyoke Community College, Holyoke, Massachusetts. Dendromorphometry is defined as the art and science of measuring trees in the field and incorporates an assessement of measurement error for each measurement technique.[5]

Tsuga Search Project[edit]

One of the most notable projects of NTS is the Tsuga Search Project, accomplished jointly with the Great Smoky Mountains National Park (GSMNP). In Tsuga Search, NTS locates, climbs, and models the largest eastern hemlocks in the GSMNP. Hemlocks as large as 1,600 cubic feet (45 m³) of trunk volume and 173.1 feet (52.8 m) in height have been confirmed through the Tsuga Search Project. Details of all NTS projects are maintained at the NTS website.

All NTS tree measurement data are generated by NTS members who are certified in NTS measurement techniques. NTS does not accept measurement data from other sources. NTS data are frequently cited within tree species descriptions in Wikipedia in an effort to correct the historical record.

See also[edit]


  1. ^ Bragg, Don C., Frelich, Lee, Leverett, Robert t., Blozan, Will, and Luthringer, Dale. 2011. The Sine Method: An Alternative Height Measurement Technique, United States Department of Agriculture, Forest Service, Southern Research Station Research Note SRS-22.
  2. ^ Bulletin of the Eastern Native Tree Society.
  3. ^ eNTS magazine.
  4. ^ ENTS Organization Name.
  5. ^ Bahr, Christopher (25 October 2013) "Mapping Tree Footprints" American Surveyor Magazine. Retrieved 2013-11-13.

External links[edit]