MYCORRHIZATION, PHYSIOGNOMY, AND FIRST-YEAR SURVIVABILITY OF CONIFER SEEDLINGS FOLLOWING NATURAL FIRE IN GRAND-TETON-NATIONAL-PARK

Ectomycorrhiza formation, survivability, and physiognomic characterist ics were assessed for conifer seedlings encountered 1 and 2 years post fire in the Huck burn site near Grand Teton National Park. Pinus conto rta Dougl. ex Loud. germinated and was abundant throughout the first g rowing season. Abies lasiocarpa (Hook.) Nutt. germinated during May an d June but was rarely encountered by September. First-year survivorshi p of P. contorta seedlings was about 50% for east-facing burn and edge and west-facing burn treatments. Mortality was higher in the west-fac ing edge treatment at about 64%. Pinus contorta seedlings collected in July and August had allocated approximately 75% more biomass to epico tyl production than to hypocotyl production, whereas by September seed lings had allocated 30-50% of their biomass to hypocotyls, regardless of site or treatment. Few or no ectomycorrhizae were formed until Sept ember. By September 100% of surviving seedlings were ectomycorrhizal. The number of ectomycorrhizae was positively correlated with the numbe r of primary needles and the root/shoot ratio. These results highlight the importance of mycorrhizae to conifer seedling survival during the initial growing season and point to alteration of carbon allocation a s a primary mechanism affecting seedling survival.