The relationships between carbon flux phenology dates and climate drivers in different impact periods.

<p>A) The coefficient of determination (<i>R</i>²) between Net Ecosystem Exchange (NEE)-derived Start of Carbon Uptake (SCU) and the cumulative daily air temperature (above 0°C) for different periods around Normalized Difference Vegetation Index (NDVI)-derived Start of Season (SOS). B) The <i>R</i>² between NEE-derived SCU and the total precipitation for different periods around NDVI-derived SOS. C) The <i>R</i>² between NEE-derived End of Carbon Uptake (ECU) and the cumulative daily air temperature (above 0°C) for different periods around NDVI-derived End of Season (EOS). D) The <i>R</i>² between NEE-derived ECU and the total precipitation for different periods around NDVI-derived EOS. Red colored line: Deciduous broadleaf forest; green: evergreen needleleaf forest; blue: grassland; orange: cropland. Stars indicate the locations with the highest <i>R</i>² for each biome and with a statistical significance at the 0.05 level. Solid circles indicate statistically significant <i>R</i>² at the 0.05 level, and hollow circles indicate statistically non-significant <i>R</i>².