The use of ectomycorrhizal conifer seedlings in the revegetation of a high-elevation mine site

Abstract

Three conifer species, Pinnscontorta Dougl., Pinusflexilis James, and Piceaengelmannii Parry, were inoculated with the ectomycorrhizal fungi Pisolithustinctorius (Pers.) Coker & Couch, Suillusgranulatus (L. ex Fr.) Kuntze, and Cenococcumgeophilum Fr. These, plus noninoculated control seedlings, were grown in a greenhouse for 8 months to assess mycorrhizal formation and seedling response. For all conifer species, top height, diameter, and seedling total dry weight were greater in the S. granulatus and control ("wild" fungus) treatments as compared with P. tinctorius and C. geophilum.In the 2nd year of the study, greenhouse container-grown conifers with ectomycorrhizae formed by the above three fungi and an unknown fungus were planted under four fertilizer treatments on a high-elevation (3200 m) molybdenum tailing pond covered with deep mine waste rock.After 4 years in the field, height growth of the seedlings (all tree species combined) inoculated with S. granulatus were greater than seedlings inoculated with P. tinctorius, C. geophilum, or control ("wild" fungus). Through four growing seasons, a sewage sludge and wood-chip treatment resulted in greater height growth than the three treatments of combined inorganic N and P, P alone, and no fertilization. The combined survival for all species and all treatments was 58% after four growing seasons.