施肥和刈割对垂穗披碱草（Elymus nutans）、中华羊茅（Festuca sinensis）和羊茅（Festuca ovina）种间竞争力的影响

试验选用青藏高原东部高寒草甸普遍存在的3种禾本科牧草垂穗披碱草(Elymus nutans)、中华羊茅(Festuca sinensis)以及羊茅(Festuca ovina)进行种间竞争的野外研究.通过测定3种牧草生物量的干重,对其进行方差分析并计算了相对产量总和(RYT)以及竞争率(CR).结果如下:对实验物种竞争率(CR)的分析表明垂穗披碱草的竞争力最强,中华羊茅次之,羊茅最差.施肥和刈割处理对于原来的竞争格局没有影响,即在施肥、刈割及其交互作用下3种牧草的竞争等级均是一致的.对试验物种混播的相对产量总和(RYT)的分析表明:在中华羊茅与垂穗披碱草的混播中,两种组成物种利用相同的资源,表现出相互竞争的趋势,这种趋势是非密度依赖的;垂穗披碱草和羊茅混播,在低密度时,羊茅和垂穗披硷草可以共享资源,但是随着密度增加,羊茅和垂穗披碱草表现出竞争相同资源的趋势;在中华羊茅和羊茅的混播中,二者在生长过程中能够共享资源,有相互促进的趋势,表现出共生的关系,且是非密度依赖的.

Effect of fertilization and clipping intensities on interspecific competition between Elymus nutans, Festuca sinensis and Festuca ovina

The experiment chooses three kinds of perennial grasses, Elymus nutans, Festuca sinensis and Festuca ovina ,which distributed widely in the east of Qing-Hai Tibet alpine meadows and used a field replacement series to study the inter-specific competition. The experiment was of four total densities and two interference factors, fertilization and clipping. The competition ability of Elymus nutans was the strongest, then Festuca sinensis, followed Festuca ovina based on Relative Yield Total (RYT) and Competition Ratio (CR) which were calculated from harvested shoot dry weights.Fertilization and clipping had no obvious influence on the competition pattern. F. sinensis/E.nutans mixture sutilized the same resource and showed competitive trend when mixed at various seeding densities.In the F.ovina/E.nutans mixtures, they shared the same resource and showed the commensal relationship when density was lower. When density increased they utilized the same resource and showed competitive relationship. F. sinensis/F.ovina mixtures shared the same resource and facilitated each other. They showed the commensal relationship and it was density-independent.