title: Scale dependence in the effects of leaf ecophysiological traits on photosynthesis: Bayesian parameterization of photosynthesis models.
abstract: Relationships between leaf traits and carbon assimilation rates are commonly used to predict primary productivity at scales from the leaf to the globe. We addressed how the shape and magnitude of these relationships vary across temporal, spatial and taxonomic scales to improve estimates of carbon dynamics. Photosynthetic CO2 and light response curves, leaf nitrogen (N), chlorophyll (Chl) concentration and specific leaf area (SLA) of 25 grassland species were measured. In addition, C3 and C4 photosynthesis models were parameterized using a novel hierarchical Bayesian approach to quantify the effects of leaf traits on photosynthetic capacity and parameters at different scales. The effects of plant physiological traits on photosynthetic capacity and parameters varied among species, plant functional types and taxonomic scales. Relationships in the grassland biome were significantly different from the global average. Within-species variability in photosynthetic parameters through the growing season could be attributed to the seasonal changes of leaf traits, especially leaf N and Chl, but these responses followed qualitatively different relationships from the across-species relationship. The results suggest that one broad-scale relationship is not sufficient to characterize ecosystem condition and change at multiple scales. Applying trait relationships without articulating the scales may cause substantial carbon flux estimation errors.
authors: Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
authors: Xiaohui
authors: X
authors: Feng
authors: Michael
authors: M
authors: Dietze
mesh_terms: D001499:Bayes Theorem; D016001:Confidence Intervals; D007700:Kinetics; D008954:Models, Biological; D009584:Nitrogen / Q000494:pharmacology; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology*; D019655:Quantitative Trait, Heritable; D012621:Seasons
chemical_list: D009584:Nitrogen
keywords: A
  max; Bayesian model parameterization; V
  cmax; chlorophyll; leaf ecophysiological traits; leaf nitrogen; photosynthesis; specific leaf area