PARENT SESSION
Poster Session 23: Soil Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
The effects of nutrient additions and tree species on the soil microbial community of a temperate hardwood forest.
Smith, Candice1, Randolph, J. C.1, 1 Indiana University, Bloomington, Indiana
ABSTRACT- Increasing rates of nitrogen deposition and elevated atmospheric carbon dioxide concentrations are two consequences of global climate changes that are affecting the temperate hardwood forests of the Lower Great Lakes states. Ecosystem processes, such as carbon storage and nutrient processing may be affected by these anthropogenically driven changes. In forest ecosystems, the largest carbon flux influencing net ecosystem productivity is soil respiration. Consequently, effects of global climate changes on terrestrial ecosystems may be greatly influenced by the response of belowground processes. We conducted a fertilization experiment at the Morgan-Monroe Ameriflux research site to examine the effects of nitrogen, phosphorus and carbon additions on two dominant tree species, sugar maple and white oak. Treatments were applied in a factorial design and were dissolved in water to simulate wet deposition. After one growing season, preliminary data indicate interactions from the nutrient additions and between tree species. Fine root biomass was greater in plots that received phosphorus (in any combination) and sugar maple produced more fine roots in response to phosphorus than white oak. Soil respiration was also greater in all plots receiving phosphorus additions, but there was no interaction between tree species. Microbial biomass, as measured by chloroform fumigation, was not affected by nutrient additions, but was slightly higher in the sugar maple plots. Arbuscular mycorrhizal (AM) colonization was assessed in all plots. While oak species do not make AM associations, this field study included herbaceous species that do make AM associations. AM colonization was higher in sugar maple plots, increased with phosphorus only treatments, and decreased with nitrogen only plots. These results suggest that this forest is nitrogen saturated and that tree species may differentially affect belowground processes.
Key words: soils, forest, nutrients, carbon