title: Canopy profiles of photosynthetic parameters under elevated CO2 and N fertilization in a poplar plantation.
abstract: A poplar plantation has been exposed to an elevated CO2 concentration for 5 years using the free air CO2 enrichment (FACE) technique. Even after such a long period of exposure, leaves of Populus x euramericana have not shown clear signs of photosynthetic acclimation. Only at the end of the growing season for shade leaves was a decrease of maximum velocity of carboxylation (Vcmax) observed. Maximum electron transport rate (Jmax) was increased by FACE treatment in July. Assimilation rates at CO2 partial pressure of 400 (A400) and 600 (A600) micromol mol(-1) were not significantly different under FACE treatment. Most notably FACE significantly decreased stomatal conductance (g(s)) both on upper and lower canopy leaves. N fertilization increased N content in the leaves on mass basis (Nm) and specific leaf area (SLA) in both CO2 treatments but did not influence the photosynthetic parameters. These data show that in poplar plantations the long-term effects of elevated CO2 on photosynthesis do not differ considerably from the short-term ones even with N deposition.
authors: Department of Forest Environment and Resources, University of Tuscia, Via S. Camillo de Lellis snc, I-01100 Viterbo, Italy. carlocalf@unitus.it
authors: Carlo
authors: C
authors: Calfapietra
authors: Ingmar
authors: I
authors: Tulva
authors: Eve
authors: E
authors: Eensalu
authors: Marta
authors: M
authors: Perez
authors: Paolo
authors: P
authors: De Angelis
authors: Giuseppe
authors: G
authors: Scarascia-Mugnozza
authors: Olevi
authors: O
authors: Kull
mesh_terms: D000064:Acclimatization; D002245:Carbon Dioxide / Q000494:pharmacology*; D004463:Ecology / Q000379:methods; D005308:Fertilizers; D007558:Italy; D009584:Nitrogen / Q000494:pharmacology*; D010788:Photosynthesis; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D018526:Plant Transpiration; D032107:Populus / Q000502:physiology*; D012621:Seasons
chemical_list: D005308:Fertilizers; D002245:Carbon Dioxide; D009584:Nitrogen