Sampling Intensity for Estimating Fuel Moisture Content in Lodgepole Pine and White Spruce Trees

Abstract

The moisture content of live and dead foliage and roundwood on 30 lodgepole pine and 27 white spruce trees was determinedduring the summer of 1987. Sample trees were selectedrandomly throughout Alberta, Canada, without regard for weather. Five sub-samples were taken for each of the five roundwood diameter size classes (< 0.5cm,0.5 - 1 cm, 1.0- .0cm,3.0- 5.0cm, 5.0-7.0cm and 7.0-10.0 cm). Moisture content of live biomass was quite similar between species for the same fuel size class, regardless of when sampling occurred. Moisture content variation within trees was about half of the variation between trees for the same fuel size class. The coefficient of variation in moisture was much less for live material (generally < 0.3) than for dead biomass (always > 0.6). Average fuel moisture content for populations of lodgepole pine and white spruce trees may be estimated to within + 10% at the 68% probability level by sampling less than 20 trees and with only 3 fuel sub-samples per tree.