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EAFES Special Symposium EX02-9

Inter-site Comparison of Ecosystem Physiological Parameters of Asian Forests

TAKAGI Kentaro (Hokkaido U)

Seasonal variation of ecosystem physiological parameters were compared among 21 Asian forests and their relation to the functional types, environmental factors, and MODIS products was investigated to find universal trend in the parameters. Target physiological parameters were maximum gross primary production at light saturation (Amax), the initial slope of the light-response curve (fai) and daytime respiration rate (Rd) for ecosystem photosynthesis, and activation energy (E0) and the reference respiration rate at 10°C (R10) for ecosystem respiration. The daily photosynthetic and respiratory parameters were determined by least-squares method using 30-min averaged daytime and nighttime net ecosystem exchange of CO2 within 29 and 39 days moving windows, respectively.

All physiological parameters showed seasonal variation peaked at mid-summer for temperate (deciduous, evergreen and mixed) and boreal forests, however the variation was small for tropical forests. Seasonal maximum of three photosynthetic parameters (Amax, fai, Rd) and E0 increased with the annual mean air temperature of the study sites, or MODIS LAI, however R10 peaked at moderate temperature regions.