Effects of forest litter on mycorrhiza development and growth of Douglas-fir and western red cedar seedlings

Abstract

Preparation of forest regeneration sites prior to conifer planting often includes slash burning or physical removal of soil organic matter. Experiments were conducted to determine if organic matter contributes to the mycorrhizal fungus inoculum potential in forest soils and to compare the growth of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and western red cedar (Thujaplicata J. Donn ex D. Donn) seedlings with and without litter. Litter and humus were found to include inoculum of both vesicular–arbuscular (VA) and ectomycorrhizal fungi. Litter amendment usually enhanced growth of host seedlings, but growth enhancement could not be fully attributed to addition of mycorrhizal inoculum or nutrients provided by litter. These findings suggested that other biological factors stimulated the growth of conifer seedlings and (or) activity of mycorrhizal fungi.