HR: 0800h
AN: B31A-0060    [Abstracts]
TI: Climatic Controls on Leaf Nitrogen Content and Implications for Biochemical Modeling.
AU: * Tcherednichenko, I A
EM: irinat@u.arizona.edu
AF: University of Arizona, Department of Civil Engineeering, Tucson, AZ 85721, United States
AU: White, M
EM: mikew@usu.edu
AF: Utah State University,Department of Watershed Sciences, 5210 Old Main Hill, Logan, UT 84322, United States
AU: Bastidas, L
EM: luis.bastidas@usu.edu
AF: Utah State University, Department of Civil and Environmental Engineering and Utah Water Research Laboratory, 4110 Old Main Hill, Logan, UT 84322, United States
AB: Leaf nitrogen (N) content, expressed as percent total nitrogen per unit of leaf dry mass, is a widely used parameter in biochemical modeling, due mainly to its role as a potentially limiting factor for photosynthesis. The amount of nitrogen, however, does not occur in a fixed amount in every leaf, but rather varies continuously with the leaf life cycle, in constant response to soil-root-stem-leaf-climate interactions and demand for growth. Moreover, while broad data on leaf N has become available it is normally measured under ambient conditions with consequent difficulty for distinguishing between genetic and time specific environmental effects. In the present work we: 1) Investigate the theoretical variation of leaf mass, specific heat capacity and leaf thickness of full sun-expanded leaves as a regulatory mechanism to ensure thermal survival along with long-term climatic radiation/temperature gradient; and discuss nitrogen and carbon controls on leaf thickness. 2) Based on possible states of partition between nitrogenous and non-nitrogenous components of a leaf we further derive probability density functions (PDFs) of nitrogen and carbon content and assess the effect of water and nutrient uptake on the PDFs. 3) Translate the results to spatially explicit representation over the conterminous USA at 1 km spatial resolution by providing maximum potential values of leaf N of fully expanded leaf optimally suited for long term climatic averages values and soils conditions. Implications for potential presence of inherently slow/fast growing species are discussed along with suitability of results for use by biochemical models.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0478 Pollution: urban, regional and global (0345, 4251)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting