Flux-Based O 3 Risk Assessment for Japanese Temperate Forests

Ground-level ozone (O3) levels are expected to increase over the twenty-first century, particularly in the region of East Asia. We performed an O3 flux-based risk assessment of C sequestering capacity in an old cool temperate deciduous forest, consisting of O3-sensitive Japanese beech (Fagus crenata), and in a warm temperate deciduous and evergreen forest dominated by O3-tolerant Konara oak (Quercus serrata), based on long-term CO2 flux observations. Light-saturated gross primary production, as a measure of C sequestering capacity, declined earlier in the late-growth season with increasing cumulative O3 uptake, suggesting an earlier autumn senescence in the O3-sensitive beech forest, but not in the O3-tolerant oak forest.