In warm temperate forests, there expands evergreen broadleaved tree species in Japan. These species retain leaves even in winter, and are situated in warmer environments than winter deciduous tree species. Winter photosynthesis is thought to increase with the progress of global warming as a major response of the forests to the increasing air temperature. Although instantaneous rates of leaf–level gas exchange have been measured, previous studies did not evaluate how winter and annual photosynthetic carbon gain change with increasing air temperature at leaf– and canopy–scales.

Japan islands offer a model system to conduct climatic research due to the wide gradient of latitude and temperature. Comparison at multiple places in Japan will provide information about the response of photosynthetic carbon gain to increasing air temperature in winter and growing season, and the phenology under climiateic changes.

In this presentation, I will show the air temperature–photosynthetic carbon gain relationship at leaf– and canopy–scales for weather stations in Japan from Hokkaido to Okinawa and show how increasing air temperature along the geographical gradient influences winter and annual carbon gain by evergreen broadleaved tree species.