Skip to Main Content
Equations to convert compacted crown ratio to uncompacted crown ratio for trees in the Interior WestAuthor(s): Chris Toney; Matthew C. Reeves
Source: Western Journal of Applied Forestry. 24(2): 76-82.
Publication Series: Miscellaneous Publication
PDF: Download Publication (110 B)
DescriptionCrown ratio is the proportion of total tree length supporting live foliage. Inventory programs of the US Forest Service generally define crown ratio in terms of compacted or uncompacted measurements. Measurement of compacted crown ratio (CCR) involves envisioning the transfer of lower branches of trees with asymmetric crowns to fill holes in the upper portion of the crown. Uncompacted crown ratio (UNCR) is measured without adjustment for holes in the crown and may be a more appropriate measurement when interest is on height to the first live branches in the crown. CCR is more commonly available because it is a standard measurement of the Forest Inventory and Analysis (FIA) program of US Forest Service, and UNCR is an optional measurement at the discretion of regional FIA units. The mean difference between UNCR and CCR of trees in the western United States (0.17 live crown) could be large enough to introduce biologically significant bias in applications that use crown ratio to derive height to crown base. Equations were developed to convert CCR to UNCR for 35 tree species in Idaho, Montana, Wyoming, Nevada, Utah, Colorado, Arizona, and New Mexico using data from the Interior West FIA unit. UNCR was modeled as a logistic function of CCR and tree diameter, and species-specific equations were fit by nonlinear regression. Root mean squared error for the regression equations ranged from 0.06 to 0.15 UNCR (mean absolute error, 0.04-0.12 UNCR). Equations for most species performed well when applied to test data that were not available at the time of model fitting.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationToney, Chris; Reeves, Matthew C. 2009. Equations to convert compacted crown ratio to uncompacted crown ratio for trees in the Interior West. Western Journal of Applied Forestry. 24(2): 76-82.
Keywordscanopy fuel, crown modeling, FIA, forest inventory and analysis, nonlinear regression
- Equations for predicting uncompacted crown ratio based on compacted crown ratio and tree attributes.
- Equations relating compacted and uncompacted live crown ratio for common tree species in the South
- Crown-condition classification: a guide to data collection and analysis
XML: View XML