In the short term, atmospheric CO2
concentration limits photosynthesis and initial increases of
up to 50% in CO2 fixation are found when the CO2
concentration around leaves is doubled. However, over longer
terms, growth is less responsive than expected from the
initial response of photosynthesis; individually-grown plants
are on an average 30–60% heavier at elevated CO2
concentrations (600–800 mLL–1; Poorter and Navas 2003).