不同CO2浓度下长白山3种树木幼苗的光合特性

选取长白山针叶树红松 (Pinuskoraiensis)、长白赤松 (Pinussylvestriformis)和阔叶树水曲柳(Fraxinusmandshurica)幼苗为研究对象 ,以开顶箱的方式控制CO2 浓度为 5 0 0和 70 0 μmol·mol-1,经过 3个生长季CO2 处理后 ,分别测定了 3个树种的 3年生幼苗在高浓度CO2 和大气CO2 浓度下的光合特性 .结果表明 ,前两个生长季高浓度CO2 处理增强了 3个树种幼苗的光合能力 ;不同树种在相同CO2 浓度下 ,最大净光合速率及光响应参数值不同 ;第 3个生长季 ,除 5 0 0 μmol·mol-1CO2 下生长的长白赤松外 ,各树种的幼苗在高浓度CO2 下并未发生“光合驯化”现象 ;最大净光合速率及光响应参数值随CO2 处理时间的延长有不同幅度的增减 ;高浓度CO2 改变了树木幼苗对强光和弱光的利用能力 .

Photosynthetic characteristics of three tree species seedlings in Changbai Mountain under different CO2 concentrations.

The photosynthetic characteristics of three-year-old seedlings of coniferous Pinus koraiensis and Pinus sylvestriformis and broadleaf Fraxinus mandshurica in open-top chambers in Changbai Mountain were studied. Seedlings were planted at four different conditions respectively:elevated CO2 concentration(700 and 500 mumol.mol-1) and ambient CO2 concentration (control chamber and in open field). After treating of two growing seasons in the first two years, seedlings were continuously grown under different CO2 concentration for another eight weeks. The results indicated that the photosynthetic capacity of three species was enhanced under high CO2 concentration in the first two growing seasons. The maximum net photosynthetic rates and light response parameters of different tree species were different at the same CO2 concentration. No photosynthetic acclimation was observed in the third growing season except Pinus sylvestriformis seedlings grown under 500 mumol.mol-1 CO2. The increase or decrease of net photosynthetic rates and light response parameters were related to the time of CO2 treatment. Elevated CO2 concentration could alter the ability of utilizing strong light and low light of seedlings.