The Biltmore stick is a tool used by foresters to estimate tree trunk diameter at breast height. The tool very often includes a hypsometer scale to estimate height as well. It looks much like an everyday yardstick. With practice a Biltmore stick is considered to be exceptionally accurate, more often within 13 millimetres (0.5 inches) on diameters. Some foresters use the tool regularly, however, many prefer to use more accurate tools such as a diameter tape to measure diameter at breast height (DBH) and a clinometer to measure height. On the other end of the spectrum, some foresters consider the use of a Biltmore stick to be no more accurate than their own visual estimates (based on experience estimating the height and DBH of trees), and make it practice for their surveys to be largely completed in this manner.
The Biltmore stick uses the principle of similar triangles. Similar triangles involve using identical angles but different side lengths.
Diameter at breast height (DBH) is measured by holding the stick a fixed distance, usually 25 inches (64 cm), from the eye, and at breast height, which in the United States is 4.5 feet (1.4 m) up the bole of the tree. The left side of the stick is flush with the left side of the tree. The number where the right side of the tree lines up with the stick is the approximate DBH of the tree.
To measure height, the user stands a fixed distance from the tree, usually 66 feet (20 m) in the United States. The stick is held upright, with the back edge of the stick facing the user. The back edge of the stick will be marked with 1, 2, 3, 4, and 5 log markings, indicating the number of 16-foot (4.9 m) logs in a tree. The bottom of the stick should line up with the bottom of the tree's trunk. The height of the tree is how high the tree goes up on the stick to a merchantable top.
Tree height is measured to a merchantable top, the point at which a tree can be accepted for use by a sawmill. This point can be reached either by defects (extreme sweep, crook, deviating branching, or other defects) or at a diameter limit for very straight trees. A common cutoff is 4 inches (10 cm) diameter, which is acceptable for pulpwood.
The Biltmore stick is so named because it was developed at the Biltmore Estate, one of the first places in the United States where forestry was applied as a science. Gifford Pinchot, the future first chief of the United States Forest Service, and then Carl A. Schenck were hired in the 1890s to restore 125,000 acres (510 km2) of land around the Biltmore estate to a healthy forest. Schenck was the developer of the Biltmore stick.
Ever since this time, the Biltmore stick has been used by foresters to quickly cruise timber.
This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (May 2020) (Learn how and when to remove this template message)
- Nix, Steve (April 15, 2017). "The Amazing Tree Measuring Stick". ThoughtCo. Retrieved 6 June 2019.
- "Asheville, NC 2000 Teachers' Tour". web.archive.org. Archived from the original on 4 July 2008. Retrieved 6 June 2019.
- Slusher, John P. "How to Measure Trees and Logs". extension2.missouri.edu. Retrieved 6 June 2019.
- "FOR-9 A LANDOWNER'S GUIDE: MEASURING FARM TIMBER". www2.ca.uky.edu. Retrieved 6 June 2019.
- "Tree Tech Consulting - Technical Reports - The Biltmore Stick". www.tree-tech.com. Retrieved 6 June 2019.
- "Tools for Measuring Trees". web.archive.org. Archived from the original on 24 January 2007. Retrieved 6 June 2019.
- Finlayson, W.; Tchanou, Z. (1975). "Sources of error in Biltmore stick type instruments". The Commonwealth Forestry Review. 54 (3/4): 290–295. JSTOR 42604446.
- Jackson, A. G. (1 September 1911). "The Biltmore Stick and its Use on National Forests". Journal of Forestry. 9 (3): 406–411. doi:10.1093/jof/9.3.406 (inactive 2021-01-13).CS1 maint: DOI inactive as of January 2021 (link)
- Dixon, R. G. (1973). "The Samoan diameter stick". The Commonwealth Forestry Review. 52 (3): 266–269. JSTOR 42605442.