大气CO_2浓度和温度升高对岷江冷杉(Abies faxoniana)幼苗针叶化学特性的影响

Effects of Elevated CO_2 and Temperature on Needle Chemistry of Abies faxoniana Seedlings

以6年生岷江冷杉(Abies faxoniana)幼苗为研究对象,利用控制环境生长室进行了2个生长季的大气CO2浓度倍增和增温(+2.2℃)处理,旨在探讨岷江冷杉幼苗针叶化学特性对CO2浓度倍增和增温的响应.结果表明:大气CO2浓度倍增对岷江冷杉幼苗针叶的叶绿素含量无显著影响,但降低了针叶N、P和纤维素含量,并增加了针叶可溶性糖和淀粉含量.增温显著降低了1年生针叶的叶绿素b含量,同时降低了当年生和1年生针叶的N、P和纤维素含量;显著提高了针叶的可溶性糖和淀粉含量.CO2浓度倍增和增温同时作用显著增加了针叶叶绿素含量,但降低了针叶N、P和纤维素含量,而对针叶可溶性糖和淀粉含量无显著影响.大气CO2浓度倍增和增温对针叶的叶绿素、N和碳水化合物含量有显著的交互作用.在大气CO2浓度倍增和增温条件下,岷江冷杉针叶化学性质将发生改变,可能影响针叶的生物化学过程和凋落物分解.

The subalpine coniferous forests in eastern Qinghai-Tibet Plateau provide a natural laboratory for studying the effects of climate change on terrestrial ecosystems. However, little is known about the effects of elevated CO2 and temperature on leaf chemistry of tree seedlings. 6-year-old Abies faxoniana seedlings were grown under control （CON, ambient CO2 concentration and temperature）, elevated CO2 concentration （EC, ambient CO： concentration ＋ 347 μmol mol^1, ambient temperature）, elevated temperature （ET, ambient temperature ＋ 2.2 ℃, ambient CO2 concentration） and the interaction with elevated CO2 concentration and temperature （ECT, ambient CO2 concentration ＋ 345 μmol mol^-1, ambient temperature ＋ 2,1 ℃） in environment-controlled chambers. After 2 growing seasons, seedlings were harvested and measured for needle chlorophyll, C, N, P and soluble sugar, starch and cellulose in current-year and one-year-old needles. Compared with CON, EC did not affect chlorophyll in current-year and one-year-old needles, but led to a decline of needle N and P, as well as lower cellulose in needles at two layers. EC induced an increase in the concentrations of soluble sugar and starch in needles. Elevated temperature tended to reduce Chl b concentration in one-year-old needle. Needle N, P and cellulose concentrations in current-year and one- year-old needles were lower under elevated temperature than ambient temperature. Soluble sugar and starch concentrations in needles tended to increase with elevated temperature. Significant combination effects of elevated CO2 and temperature on needle chlorophyll, N, P and carbohydrates were found. Both elevated CO2 and temperature may alter leaf chemistry, indicatingclimate change may influence not only biochemical processes of leaves but also fundamental ecosystem processes, such as litter decomposition. Tab 3, Ref40