HR: 1340h
AN: B43A-0258    [Abstracts]
TI: The Effect of Phosphorus Availability on Fine Root Decomposition in Western Oregon
AU: * van Huysen, T
EM: tiffany.vanhuysen@oregonstate.edu
AF: Department of Forest Science, 321 Richardson Hall Oregon State University, Corvallis, OR 97331
AU: Harmon, M
EM: mark.harmon@oregonstate.edu
AF: Department of Forest Science, 321 Richardson Hall Oregon State University, Corvallis, OR 97331
AU: Perakis, S
EM: steven.perakis@oregonstate.edu
AF: Department of Forest Science, 321 Richardson Hall Oregon State University, Corvallis, OR 97331
AB: We are examining fine root decomposition at three sites in western Oregon, USA to determine whether phosphorus availability serves as a proximate control of nitrogen dynamics in fine root decomposition. More specifically, we are testing the hypothesis that external (soil P) and internal (root P content) supplies of P influence release of N from roots decomposing in soils that are low in available P. A factorial fertilization experiment is being used to test this hypothesis. At each of the three sites, P fertilizer has been added to six plots to enhance soil P availability and six plots have remained unfertilized. Litterbags containing Douglas-fir roots, needles, or twigs were placed in all plots. Half of the litterbags contain plant material from seedlings that were fertilized with P, resulting in four treatments: P added to soil and litter, P added to soil but not to litter, P added to litter but not to soil, and P not added to soil or litter (control). Data from soil cores collected in the treatment plots at each site and extracted with Bray solution indicate that extractable P is significantly higher (P < 0.001) in the plots that have been fertilized with P. Extractable P (mg P/kg soil) is approximately 50 mg higher in the fertilized plots than the unfertilized plots. Material from litterbags collected this summer is currently being processed and analyzed for C, N, and P content and mass loss to determine decomposition rates for the three litter types.
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
SC: Biogeosciences [B]
MN: Fall Meeting 2005