Root biomass distribution under three cover types in a patchy Pseudotsuga menziesii forest in western Canada

Abstract

We investigated the relationship between cover type and root biomass distribution and allocation to different root size classes in a naturally regenerated, dry, Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) forest in the southern interior of British Columbia, Canada. The site was selectively harvested 32 years previously; residual stems were 30 cm and 130-170 years old at breast height at the time of study. A total of nine pits (each measuring 1.0 m x 1.0 m) were excavated to a depth of 1.0 m under three different cover types: mature timber, grassy (Calamagrostis rubescens) openings (canopy gaps), and regeneration clumps. Total (all diameters) live root biomass ranged from 4.7 kg/m2 under the mature timber to 1.9 kg/m 2 under both regeneration clumps and grassy openings. Thin root (0.1 cm