Diameter Measurement in Bald Cypress

Abstract

The usual practice of measuring diameter at 4.5 feet ( 1.3 m) or D_bh is meaningless in wetland tree species such as bald cypress (Taxodium distichum (L.) Rich.), due to the presence of fluted basal swells. Since buttress dimensions usually have no consistent relation to volume or form in the tree, the current practice among life-sciences professionals is to measure stem diameter 18 in (50 cm) above `pronounced' butt swelling. This measure is termed normal diameter (D_n). This paper contrasts the use of six fixed-height diameter-measurement points ranging from 6 ft ( 1.8 m) to 11 ft (3.4 m) against D_n (a variable-height measurement point) for predicting cubic volume. Results show an increase in precision using the upper live fixed-height measurements over D, and a considerable increase in precision using diameter measured at 10 ft (3.0 m) and 11 ft (3.4 m). Since results improved only slightly using diameter measured at 11 ft (3.4 m) over 10 ft (3.0 m), diameter at 10 ft (D₁₀) is recommended as a better alternative than D, for working with cypress.

Citation

Parresol, Bernard R.; Hotvedt, James E. 1990. Diameter Measurement in Bald Cypress. Forest Ecology and Management, 33/34 (1990) 509-515