A Comparison of earlywood–latewood Demarcation Methods – A case study in Loblolly PINE

Abstract

Demarcating the transition from earlywood (EW) to latewood (LW) is important for accurately estimating the width of both wood types within an annual ring, their respective densities and the proportion of LW within an annual ring. Different methods have been used to define the transition from EW to LW and include Mork’s index, the threshold density method and the inflection point method. In loblolly pine (Pinus taeda L.) a threshold value of 480 kg/m3 (basic density) has conventionally been used to demarcate EW from LW. In this study the three methods: a threshold density of 480 kg/m3, the inflection point method and Mork’s index were used to define the point at which EW transitioned to LW using annual rings for 20 loblolly pine breast height increment cores. Significant correlation was observed among the three methods in identifying the demarcation point. However, the results indicated that EW-LW demarcation points identified using the three methods in juvenile wood rings were different to mature wood rings; with the most pronounced differences being observed for Mork’s index.