Jenny, A diameter tape is used in forestry. It measures the girth of a tree and the scale is marked to read the diameter of the tree instead of the girth measurement. Essentially every value marked is the actual girth divided by pi. Thus on a tree that was 9.5 feet in girth would be read on the tape as just a touch over 3 feet in diameter. ENTS measurements generally use girth as that is a direct physical measurement of the tree. The diameter tape assumes that the tree's cross-section is circular (the division by pi). Therefore for tree that are not perfectly round it in every case exaggerates the actual cross sectional area of the tree. In some of our formulas we make the same assumption, but there is no reason to introduce these errors into the raw data set, and the use of this conversion in various formulas is made with the knowledge that it is only an approximation.
Ed ----- Original Message ----- From: "JennyNYC" <[email protected]> To: "ENTSTrees" <[email protected]> Sent: Tuesday, April 07, 2009 10:32 AM Subject: [ENTS] Re: Rucker Index Josh, Thanks. Found Ed Frank's article on Rucker Index plus all the measuring guides. A 'diameter tape' is mentioned. I assume this is a different type of measuring tape than a regular one? Thanks again. Jenny --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
