中文摘要：

采用全自动微气候控制的“人工模拟气候实验系统”研究了增温和CO2浓度加倍对川西亚高山针叶林土壤硝态氮（N03-N）、铵态氮（NH4-N）、游离氨基酸（FAA）、可溶性有机氮（DON）和可溶性总氮（TSN）的影响。结果表明：①在种植油松苗木组，增温处理显著降低了土壤NO3-N含量，不同处理0-15cm土层NO3-N含量均显著小于15-30cm层；而在未种树组，增温处理显著增加了土壤NOi-N含量，0-15cm土层NO；-N含量显著高于15-30cm层，这表明增温促进了油松苗对NO3--N的吸收。②在种植油松苗木组，增温（ET）、增CO2（EC）及两者的共同作用（ETC）均显著增加了土壤NH4＋-N、DON和TSN含量；在未种树组，ET显著增加了土壤NH4＋-N、FAA、DON和TSN含量，EC和ETC对NH4＋、FAA、DON和TSN含量具有微弱影响或没有显著影响。不同处理0-15cm层土壤NH4-N、FAA、DON和TSN的含量显著大于15-30cm层。③种植油松苗木组土壤NOi-N、NH4＋-N、FAA、DON和TSN含量均显著低于未种树组，这是由植物对氮素的吸收消耗造成的。研究结果表明，EC、ETC主要通过植物根系作用促进了NH4＋-N、DON和TSN含量增加，而ET处理通过影响土壤微生物和植物根系来促进NH4＋-N、FAA、DON和TSN含量的增加。

英文摘要：

The Qinghai-Tibetan Plateau, often referred to as Earth＇s climate system. Chinese pine （ Pinus tabulaeformis ） ＂the Third Pole＂ of the world, plays an important role in the forest is one of the most important vegetation types in the subalpine regions of western Sichuan, China, but our knowledge about the response of soil in this forest ecosystem, especially soil total soluble nitrogen to climate change is limited. The effects of elevated temperate （ET, ambient temperature ＋ （2.5±0.5）℃）, CO2concentration doubling （EC, ambient CO2 concentration ＋ 350 μmol/mol） and their interaction （ETC） on soil total soluble nitrogen, including nitrate nitrogen （NO3--N）, ammonium nitrogen （NH4＋-N）, free amino acid （FAA） , dissolved organic nitrogen （DON） and total soluble nitrogen （TSN） of Chinese pine forest soils were investigated by using an automatic micro-climate controlled system. 1 ） Compared with the control （ CKP）, ET significantlydecreased NO3-N concentrations in the seedling treatment, and the concentration of NO3--N in the 0--15 cm soil layer was lower than that in the 15--30 cm layer. By contrast, ET markedly increased NO3-N concentrations in the plant-free treatment, and the concentration of NO3--N in the 0--15 cm soil layer was higher than that in the 15--30 cm layer. These results indicated that the absorption of NO3--N by Chinese pine seedlings of was enhanced under ET to meet the demands of growth, especially in the 0--15 cm soil layer. This was likely due to the occurrence of more fine roots in the upper soil layer than the deeper layer. NO3--N appears to be one of the most important forms of soil soluble nitrogen utilized by Chinese pine. 2） Furthermore, ET, EC and ETC induced an increase in the concentrations of NH4＋-N, DON and TSN in the seedling treatment. However, in the plant-free treatment NH4＋-N, FAA, DON and TSN concentrations were significantly enhanced under ET; but EC and ETC had little influence on their concentrations. These resul