Inoculation and field testing of Sitka spruce and Douglas fir with ectomycorrhizal fungi in the United Kingdom

Picea sitchensis and Pseudotsuga menziesii seedlings were grown in containers, inoculated with ectomycorrhizal fungi, and planted in British forestry sites. Root samples taken during the year after planting were assessed for mycorrhiza formation. Survival and shoot height were assessed at the end of each year. Observations were made each autumn on the occurrence of sporophores of ectomycorrhizal fungi. Pot experiments were used to assess the colonization potential of soils from the experimental locations. Assessment of mycorrhiza formation by the inoculant fungi both before planting and the following year showed much variation among the fungi used. Similar variation was found among field sites. Inoculation with Laccaria isolates was most successful. Height measurements are reported for the first 2 years after planting, at which time there were few significant effects on growth of Picea sitchensis or Pseudotsuga menziesii seedlings. Experimental assessment of colonization potential was of little value in this work for predicting events in the forest.