Compatible Taper and Volume Models for Atlantic White Cedar (Chamaecyparis thyoides L.) in Eastern North Carolina

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Date

2009-06-26

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Abstract

Efforts to restore Atlantic White Cedar (Chamaecyparis thyoides L.) over parts of its historical range have led to an increased interest in the species for commercial logging. With this interest comes the need to develop equations to estimate the taper and volume of Atlantic White Cedar (AWC) stems. A total of 210 trees were selected from three different regions of eastern North Carolina (Outer Coastal Plain, Carolina Bays, and Sandhills) for the development of taper and volume models. Diameters at approximately 5 foot height intervals were measured from each selected tree. Several previously developed taper model forms were examined for their fit to this data using mixed models. Of these examined models the Demaerschalk (1972) model had the best fit, though a common trend was noted in the residuals of several of the candidate models. A new taper model composed of a linear function (L), an exponential decay curve (E), and a sine function (S), termed L.E.S., was derived in order to account for this common trend in the residuals and achieved an improved fit to the AWC data. Though significant differences between the three measured regions were identified by the L.E.S. taper model at an alpha level of 0.05, these differences did not translate into any practical differences. Integration of the L.E.S. taper model created an associated compatible volume model for AWC. Estimated total stem volumes from this new volume model and two other simple linear regression total stem volume models were compared to actual total stem volume calculated using Smalian’s equation. Though no practical difference was found to exist between the new volume model and one of the simple linear regression total stem volume models, the new model does allow volumes to be estimated between any two heights or diameters. The models presented in this research should help land managers more accurately assess their stands of AWC.

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Keywords

Atlantic White Cedar, taper model, volume model

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Degree

MS

Discipline

Forestry

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