title: Canopy carbon budget of Siebold's beech (Fagus crenata) sapling under free air ozone exposure.
abstract: To determine the effects of ozone (O3) on the canopy carbon budget, we investigated photosynthesis and respiration of leaves of Siebold's beech saplings under free air O3 exposure (60 nmol mol(-1), during daytime) in relation to the within-canopy light gradient; we then calculated the canopy-level photosynthetic carbon gain (PCG) and respiratory carbon loss (RCL) using a canopy photosynthesis model. Susceptibilities of photosynthesis and respiration to O3 were greater in leaves of upper canopy than in the lower canopy. The canopy net carbon gain (NCG) was reduced by O3 by 12.4% during one growing season. The increased RCL was the main factor for the O3-induced reduction in NCG in late summer, while contributions of the reduced PCG and the increased RCL to the NCG were almost the same in autumn. These results indicate contributions of changes in PCG and RCL under O3 to NCG were different between seasons.
authors.affiliation: Silviculture and Forest Ecological Studies, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Watanabe
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Hoshika
authors.forename: Naoki
authors.initials: N
authors.lastname: Inada
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Koike
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D019069:Cell Respiration / Q000187:drug effects; D029964:Fagus / Q000187:drug effects / Q000502:physiology*; D010126:Ozone / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects; D012621:Seasons
chemical_list: D000393:Air Pollutants; D002245:Carbon Dioxide; D010126:Ozone; D002244:Carbon
keywords: Canopy carbon budget; Free air ozone exposure; Light gradient; Sensitivity to ozone; Siebold's beech