ensity d (548 umol mol-1)atmospheric [CO2]cond 世出把 E Takeuchi Y.et al 2001.Plat,Coll Emer.24.1257-1268 Pan.C17-10 e rate of 出 片 20 Han OM ct a. 03.Tree 23.851-857 tive c latio ed at ligh eturated conditio g4 Mean (± SE) daily integrated photosynthetic photon flux density (PPFD, mol m−2 d−1) at the top of, and within, a Populus tremuloides crown under current ambient (343 µmol mol−1) and elevated (548 µmol mol−1) atmospheric [CO2] conditions. Takeuchi Y. et al. 2001. Plant, Cell & Envir. 24, 1257-1268 leaf N concentrations and specific leaf area (SLA) in a Populus tremuloides canopy under open-air CO2 enrichment during the 1999 growing season. Takeuchi Y. et al. 2001. Plant, Cell & Envir. 24, 1257-1268 Upper-canopy measurements were from unshaded leaves on the main terminals. Mid- and lower-canopy positions were fixed at 120 and 40 cm above the ground, respectively. Variations in (a) the rate of light-saturated photosynthesis (Amax), (b) the maximum rate of carboxylation (Vcmax) and (c) the maximum rate of electron transport (Jmax) along first-order branches Upper Middle Bottom in the upper, middle, and lower crown of Pinus densiflora in July 2001. Han QM et a. 2003. Tree Physiology 23, 851-857 343 ppm 548 ppm Takeuchi Y. et al. 2001. Plant, Cell & Envir. 24, 1257-1268 Photosynthesis light response curves Populus tremuloides canopies July Aug. Sept Positive correlation between leaf nitrogen content and Pmax (measured at light and CO2 saturated condition Koike T. et al. 2004. in Global Environmental Change in the Ocean and on Land (Eds., M. Shiyomi et al.), pp. 453–472 Sunny crown and seedlings at gap Shady crown and seedlings at the forest floor Koike T. et al. 2004. in Global Environmental Change in the Ocean and on Land (Eds., M. Shiyomi et al.), pp. 453–472 Relation between leaf nitrogen content (N) and Psat (light-saturated photosyn￾thetic rate) in canopy trees and seedlings Han QM et a. 2003. Tree Physiology 23, 851-857