中文摘要：

采用开顶式有机玻璃罩（OTCs）及紫外灯分别模拟气候变暖和紫外辐射B（uV—B）增强，对位于气候变暖和uV—B增强突出的青藏高原东缘、高山峡谷地云杉（Piceaasperata）幼苗的光合气体交换和叶绿素荧光参数进行测定分析，探讨云杉幼苗对气候变暖和uV—B增强的光合响应特性。结果显示：（1）UuB辐射增强显著抑制了云杉幼苗茎和根的伸长生长以及生物量的累积，显著降低了云杉幼苗的净光合速率（Pn）、最大光合速率（Pmax）和表观量子产量（圣），但是提高了光补偿点（LCP）；uV—B辐射增强导致了云杉幼苗光合系统Ⅱ（PSII）的光抑制，使PSII有效量子产量（ФPSII）显著降低。（2）单纯OTC模拟增温显著提高了云杉幼苗的Pn和Pmax，而对气孔导度（Gy）、蒸腾速率（Tr）和中无显著影响。（3）模拟增温缓解了UV-B增强对云杉幼苗光合作用的抑制作用，显著提高了UV—B胁迫下幼苗的Pn Pmax PSII的潜在量子效率（Fv／Fm）和有效量子产量（ФPSII），并且提高了uV—B胁迫下幼苗茎、根的生长以及生物量的累积。研究表明，在未来气候变暖和UV—B辐射增强同时存在时，气候变暖能够在一定程度上缓解uV—B增强对云杉林光合作用的抑制作用。

英文摘要：

Using open-top Chambers（OTCs） and UV-lamps,we manipulated climate warming and enhanced UV-B radiation. The parameters of photosynthetic gas exchange and chlorophyll fluorescence of Picea as- perata seedlings in the eastern fringe of the Tibetan Plateau,where climate warming and enhanced UV-B radiation（UV-B） were severe,were measured to investigate its photosynthetic responses to the two worse- ning environmental factors. The results showed that： （1）Enhanced UV-B restrained the net photosynthetic rate （Pn）, the maximum photosynthetic rate（Pin,x） and the apparent quantum yield（Ф）. However,it increased the pho- tosynthetic light compensation point（LCP）. In addition,enhanced UV-B induced photo-inhibition of the photosyn- thetic system II（PS Il） in P. asperata seedlings, and it reduced the effective quantum yield of PS II（ФPSII ）. In the end,enhanced UV-B significantly inhibited shoot elongation, root growth and biomass accumulation. （2）OTCs warming significantly enhanced Pn and P but it had no effects on G ,Tr and Ф. （3）UV-B effects on pho- tosynthesis were amended by warming to some extent,which could be judging from the increased Pn ,P intrinsic effieiency（Fv/Fm） and ФPSII of PS II ,and the improved growth. In the end,warming could alleviate the harmful effects of enhanced UV-B on photosynthesis of P. asperata.