中国青藏高原东部冷地早熟禾生长与潜在的繁殖对降水量缺乏的反应

Growth and potential reproduction of Poa crymophila in response to season precipitation shortage in the eastern tibetan plateau,China

在中国青藏高原的东部,2006年生长季节的降雨量比前一年少.为了探索草对干旱年的反应策略,研究了降雨量丰富的2005年与降雨量贫乏的2006年高寒草甸优势种群冷地早熟禾生长与潜在的繁殖变化.在降雨量贫乏的年份,冷地早熟禾生殖枝生物量、地上与地下生物量明显的减少,但地上/地下生物量之比和营养枝生物量增加.在2006年花序C的含量明显增加,但根C的含量明显减少,植株各构件N的含量与C/N比并没有明显的不同.2005年与2006年的有性繁殖没有明显的不同,季节降雨量的缺乏导致更高的早春萌蘖或分蘖死亡.这个结果表明:冷地早熟禾对降雨量缺乏(干旱)表现为更小的植株体,分配更多比例的生物量到地上,分配更多的C到花序,繁殖方式倾向于有性繁殖.

The growing season in 2006 existed a quite less precipitation than previous years in the eastern of Tibetan Plateau, China. In order to explore the response strategies of the grass to drought year, the variations of growth and potential reproduction of Poa crymophila between rich （2005） and poor rainfall year （2006） were studied. Reproductive shoot biomass, above and belowground biomass pronounced decreased in the poor rainfall year, but the ratio of above/belowground biomass and vegetative shoot biomass increased. Carbon content in inflorescence increased significantly in 2006, but decreased significantly in root. Nitrogen contents and the C/N ratios in plant components were not significantly different. Sexual reproduction in 2005 and 2006 was not different. Season precipitation shortage could result in the higher mortality of vernal budding shoots or tillers. The results suggested that P.crymophila response to poor rainfall year （drought） by a smaller plant body, allocating more proportional biomass to aboveground, altering more carbon to inflorescence, and altering its reproductive way to sexual.