云杉种子萌发和幼苗生长对气候变暖与UV B辐射增强的响应

采用开顶式有机玻璃罩(OTCs)及紫外灯分别模拟气候变暖和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的高山峡谷地云杉种子萌发、幼苗生长和光合色素含量的变化进行测定分析,探讨云杉对气候变暖和UV-B增强的响应机理。结果显示:(1)UV-B辐射增强对云杉种子萌发无显著影响,但显著抑制萌发幼苗的生长、降低其针叶叶绿素含量,并造成幼苗大量死亡(P<0.05)。(2)气候变暖使云杉种子提前萌发,并提高了发芽势、发芽率和发芽指数,促进幼苗生长和叶绿素的积累,显著降低幼苗死亡率(P<0.05)。(3)气候变暖缓解了UV-B增强对云杉萌发幼苗生长和叶绿素含量的抑制作用,并降低了UV-B胁迫下幼苗的死亡率。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增强对云杉林早期更新带来的抑制作用。

Responses of Seed Germination and Seedling Growth of Picea asperata to Climate Warming and Enhanced UV B Radiation

The study site was located on the eastern fringe of the Tibetan Plateau where climate warming and enhanced UV-B radiation(UV-B) were severe.Seed germination,seedlings growth and photosynthetic pigments content of Picea asperata seedlings in the eastern fringe of the Tibetan Plateau were measured to investigate the responses of P.asperata seedlings to climate warming and enhanced UV-B using Open-top Chambers(OTCs) and UV-lamps.The results showed that:(1)Enhanced UV-B radiation did not significantly affect seed germination.However,it significantly inhibited seedling growth,decreased chlorophyll contents,and caused a high seedling mortality of P.asperata(P<0.05).(2)Warming markedly stimulated seed germination,facilitated seedling growth and increased chlorophyll content in needles of P.asperata(P<0.05).(3)Warming alleviated the harmful effects of enhanced UV-B radiation on seedling growth and chlorophyll content,and decreased the high mortality induced by enhanced UV-B.It could be reasoned that climate warming would alleviate the harmful effect of enhanced UV-B on early regeneration of spruce forest.