[Effect of elevated CO2 concentration on carbohydrate and nitrogen contents in seedlings foliage of three tree species in Changbai mountain].

The contents of sucrose, fructose, soluble total sugar, starch and total nitrogen were analyzed in seedlings of Pinus koraiensis, Pinus sylvestriformis and Fraxinus mandshurica grown for three growing seasons in open-top chambers in Changbai mountain under elevated CO2 (700, 500 mumol.mol-1) and ambient CO2 (350 mumol.mol-1) concentrations. The results showed that in the first two growing seasons the treatment of 700 mumol.mol-1 CO2 accumulated the contents of starch in Pinus sylvestriformis and Fraxinus mandshurica seedlings, while total nitrogen content significantly decreased in Pinus koraiensis seedlings under 700 and 500 mumol.mol-1 CO2. The content of starch increased and the content of total nitrogen decreased in Pinus koraiensis and Fraxinus mandshurica seedlings grown under 700, 500 mumol.mol-1 CO2 at the first two weeks in the third growing season. The change of starch and total nitrogen in Fraxinus mandshurica at the eighth week was similar to the first and second week. There was no significant increase or decrease of C and N content in Pinus sylvestriformis at the third growing season. CO2 concentration affected the forms of carbohydrate accumulation in foliage.