Abstract
Current terrestrial ecosystem models are usually driven with global average annual atmospheric
carbon dioxide (CO2) concentration data at the global scale. However, high-precision CO2 measurement
from eddy flux towers showed that seasonal, spatial surface atmospheric CO2 concentration
differences were as large as 35 ppmv and the site-level tests indicated that the CO2 variation exhibited
different effects on plant photosynthesis. Here we used a process-based ecosystem model driven with two
spatially and temporally explicit CO2 data sets to analyze the atmospheric CO2 fertilization effects on the
global carbon dynamics of terrestrial ecosystems from 2003 to 2010. Our results demonstrated that CO2
seasonal variation had a negative effect on plant carbon assimilation, while CO2 spatial variation exhibited
a positive impact. When both CO2 seasonal and spatial effects were considered, global gross primary
production and net ecosystem production were 1.7 Pg C·yr−1 and 0.08 Pg C·yr−1 higher than the simulation
using uniformly distributed CO2 data set and the difference was significant in tropical and temperate evergreen
broadleaf forest regions. This study suggests that the CO2 observation network should be expanded
so that the realistic CO2 variation can be incorporated into the land surface models to adequately account
for CO2 fertilization effects on global terrestrial ecosystem carbon dynamics.
