Influence of ozone pollution and climate variability on net primary productivity and carbon storage in Chinaʹs grassland ecosystems from 1961 to 2000

Our simulations with the Dynamic Land Ecosystem Model (DLEM) indicate that the combined effect of ozone, climate, carbon dioxide and land use have caused Chinaʹs grasslands to act as a weak carbon sink during 1961–2000. This combined effect on national grassland net primary productivity (NPP) and carbon storage was small, but changes in annual NPP and total carbon storage across Chinaʹs grasslands showed substantial spatial variation, with the maximum total carbon uptake reduction of more than 400 g m−2 in some places of northeastern China. The grasslands in the central northeastern China were more sensitive and vulnerable to elevated ozone pollution than other regions. The combined effect excluding ozone could potentially lead to an increase of 14 Tg C in annual NPP and 0.11 Pg C in total carbon storage for the same time period. This implies that improvement in air quality could significantly increase productivity and carbon storage in Chinaʹs grassland ecosystems.