Effects of elevated CO2 concentrations on photosynthesis, dark respiration and RuBPcase activity of three species seedlings in Changbai Mountain

Abstract

Two-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis andFraxinus mandshurica were treated in open-top chambers with elevated CO2 concentrations (700 μL·L−1, 500 μL·L−1) and ambient CO2 concentrations (350 μL·L−1) in Changbai Mountain from June to Sept. in 1999 and 2001. The net photosynthetic rate, dark respiration rate, ribulose-1,5-bisphosphate carboxlase (RuBPcase) activity, and chlorophyll content were analyzed. The results indicated the RuBPcase activity of the three species seedlings increased at elevated CO2 concentrations. The elevated CO2 concentrations stimulated the net photosynthetic rates of three tree species exceptP. sylvestriformis grown under 500 μL·L−1 CO2 concentration. The dark respiration rates ofP. koraiensis andP. sylvestriformis increased under concentration of 700 μL·L−1 CO2, out that ofF. mandshurica decreased under both concentrations 700 μL·L−1 and 500 μL·L−1 CO2. The seedlings ofF. mandshurica decreased in chlorophyll contents at elevated CO2 concentrations.