The long-term effect of elevated CO2 concentrations on needle dark respiration of two coniferous spe- cies—Pinus koraiensis and Pinus sylvestriformis on the Changbai Mountain was investigated using open-top chambers. P. koraiensis and P. sylvestriformis were exposed to 700, 500 μmol·mol-1 CO2 and ambient CO2 (approx. 350 μmol·mol-1) for four growing seasons. Needle dark respiration was meas- ured during the second, third and fourth growing seasons’ exposure to elevated CO2. The results showed that needle dark respiration rate increased for P. koraiensis and P. sylvestriformis grown at elevated CO2 concentrations during the second growing season, could be attributed to the change of carbohydrate and/or nitrogen content of needles. Needle dark respiration of P. koraiensis was stimu- lated and that of P. sylvestriformis was inhibited by elevated CO2 concentrations during the third growing season. Different response of the two tree species to elevated CO2 mainly resulted from the difference in the growth rate. Elevated CO2 concentrations inhibited needle dark respiration of both P. koraiensis and P. sylvestriformis during the fourth growing season. There was consistent trend be- tween the short-term effect and the long-term effect of elevated CO2 on needle dark respiration in P. sylvestriformis during the third growing season by changing measurement CO2 concentrations. How- ever, the short-term effect was different from the long-term effect for P. koraiensis. Response of dark respiration of P. koraiensis and P. sylvestriformis to elevated CO2 concentrations was related to the treatment time of CO2 and the stage of growth and development of plant. The change of dark respiration for the two tree species was determined by the direct effect of CO2 and long-term acclimation. The prediction of the long-term response of needle dark respiration to elevated CO2 concentration based on the short-term response is in dispute.
ZHOU YuMei1, HAN ShiJie1, ZHANG HaiSen1, XIN LiHua2 & ZHENG JunQiang1 1 Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
采用DGGE（Denaturing Gradient Gel Electrophoresis）技术，于2003年的7-9月中旬对高浓度CO2（700和500μmol·mol^-1）处理下的红松幼苗根际和根外0-10cm土壤微生物群落结构进行了研究．结果表明，大气CO2浓度升高对红松根际和非根际土壤细菌群落结构产生了较大的影响，主要表现为部分细菌物种的出现，或原有细菌数量的丰富以及原有物种的消失或其数量被削弱的现象，但主要建群种未变．
