PARENT SESSION
Poster Session # 10: Soil Ecology.
Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Differences in ectomycorrhizal infection of conifer seedlings across an alpine-treeline ecotone: Relative importance of variation in soil properties and microclimate.
Hasselquist, Niles1, Germino, Matt1, McGonigle, Terence1, Smith, William2, 1 Idaho State University, Pocatello, ID2 Wake Forest University, Winston-Salem, NC
ABSTRACT- The importance of mycorrhizae to plants in stressful environments, such as for conifer seedlings above the elevation limits of forest, is not well known. Lower ectomycorrhizal infection rates could contribute to lower seedling survival in alpine soils. Experiments were designed to test whether seedlings were less likely to form an ectomycorrhizal symbiosis at higher versus lower altitude sites, and whether differences in microclimate or soil properties among these sites were more likely to explain variation in infection rates. Ectomycorrhizal infection of Engelmann spruce (Picea engelmannii) seedlings was measured across an altitudinal gradient from subalpine forest to alpine meadow. The percent of root tips infected was determined for seedlings that germinated in soils transplanted in a reciprocal fashion among the three sites. Three seedlings from each combination of soil and site were harvested biweekly throughout the growing season, and the percent of root tips infected were determined microscopically. Mean infection rates at the end of the growing season were 30, 13, and 0% for seedlings in the forest, treeline-ecotone, and alpine soils, respectively, and were not affected by transfer to another site. These results indicate that conifer seedlings may be less likely to establish ectomycorrhizal symbioses in treeless, alpine meadows compared to more forested sites. Moreover, site differences in infection appeared more attributable to variation in soil properties, possibly inoculum availability, than to microclimate and corresponding effects on seedling physiology.
Key words: alpine-treeline ecotone, ectomycorrhizae, Picea engelmannii