Use of the ectomycorrhizal fungus Laccarialaccata in forestry. I. Consistency between isolates in effective colonization of containerized conifer seedlings

Abstract

Four isolates of the ectomycorrhizal fungus L. laccata (Scop. ex Fr.) Berk and Br. were inoculated singly onto containerized Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), ponderosa pine (Pinus ponderosa Dougl. ex Laws.), Sitka spruce (Picea sitchensis (Bong.) Carr.), and western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedlings to detect ecotypic variation in colonization success and effects on seedling growth. All isolates formed well-formed ectomycorrhizae on all inoculated seedlings. Abundance ratings of short roots colonized did not differ between the 4 isolates for any conifer species; most inoculated seedlings developed ectomycorrhizae on over 80% of their shoot roots. There were also no differences between isolates in affecting seedling height, stem diameter and dry weight of tops and roots for all conifer species. Inoculations did not improve seedling growth over uninoculated controls. Uninoculated controls of Douglas-fir and ponderosa pine had significantly greater dry weight than their inoculated seedlings; growth of Sitka spruce and western hemlock seedlings was not affected by any inoculation treatment. L. laccata vigorously colonized the entire container rooting substrate and appears a prime candidate for artificial ectomycorrhizal inoculation of containerized western conifers.