title: Informing models through empirical relationships between foliar phosphorus, nitrogen and photosynthesis across diverse woody species in tropical forests of Panama.
abstract: Our objective was to analyze and summarize data describing photosynthetic parameters and foliar nutrient concentrations from tropical forests in Panama to inform model representation of phosphorus (P) limitation of tropical forest productivity. Gas exchange and nutrient content data were collected from 144 observations of upper canopy leaves from at least 65 species at two forest sites in Panama, differing in species composition, rainfall and soil fertility. Photosynthetic parameters were derived from analysis of assimilation rate vs internal CO2concentration curves (A/Ci), and relationships with foliar nitrogen (N) and P content were developed. The relationships between area-based photosynthetic parameters and nutrients were of similar strength for N and P and robust across diverse species and site conditions. The strongest relationship expressed maximum electron transport rate (Jmax) as a multivariate function of both N and P, and this relationship was improved with the inclusion of independent data on wood density. Models that estimate photosynthesis from foliar N would be improved only modestly by including additional data on foliar P, but doing so may increase the capability of models to predict future conditions in P-limited tropical forests, especially when combined with data on edaphic conditions and other environmental drivers.
authors.affiliation: Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, 37830-6301, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Norby
authors.affiliation: Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, 37830-6301, USA.
authors.forename: Lianhong
authors.initials: L
authors.lastname: Gu
authors.affiliation: Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, 37830-6301, USA.
authors.forename: Ivan C
authors.initials: IC
authors.lastname: Haworth
authors.affiliation: Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, 37830-6301, USA.|Department of Forestry and Wood Technology, Linnaeus University, Växjö, Sweden.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Jensen
authors.affiliation: Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Panama.
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Turner
authors.affiliation: Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, 37830-6301, USA.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Walker
authors.affiliation: Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, 37830-6301, USA.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Warren
authors.affiliation: Biosciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, 37830-6301, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Weston
authors.affiliation: Earth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
authors.forename: Chonggang
authors.initials: C
authors.lastname: Xu
authors.affiliation: Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Panama.
authors.forename: Klaus
authors.initials: K
authors.lastname: Winter
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D065928:Forests; D008954:Models, Biological; D009584:Nitrogen / Q000032:analysis*; D010176:Panama; D010758:Phosphorus / Q000032:analysis*; D010788:Photosynthesis; D018515:Plant Leaves / Q000737:chemistry*; D012044:Regression Analysis; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013045:Species Specificity; D014197:Trees / Q000378:metabolism; D014329:Tropical Climate; D014934:Wood / Q000737:chemistry*
chemical_list: D002245:Carbon Dioxide; D010758:Phosphorus; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen
keywords: N : P ratio; maximal Rubisco carboxylation rate (Vcmax); maximum electron transport rate (Jmax); nitrogen (N); phosphorus (P); photosynthesis; traits; tropical forest