多年生禾草混播草地初级生产力及群落动态研究

在青海环湖地区对3种多年生禾草的生态适应性、丰产性和种间相容性进行了试验,经连续4年的观测与分析,结果表明,3种牧草对试验区干旱寒冷的气候条件表现出良好的适应性.无芒雀麦和贫花鹅观草不能完成生殖生长过程,但营养体生长充分.在第2年和第3年,混播草地的初级生产力显著高于各单播草地,但这种差异在第4年已不存在.混播草地的三组分之间存在明显的种间竞争关系,垂穗披碱草竞争力最强,贫花鹅观草次之,无芒雀麦最弱.种群消长动态明显,垂穗披碱草在草群中的比例逐年增加,而贫花鹅观草和无芒雀麦逐年减少,无芒雀麦在第4年从混播草群中消失.

Primary productivity and community dynamics of mixed perennial grass pasture

The adaptability, productivity and inter-species competition of Elymus nutans, Roegneria pauciflora and Bromus inermis were studied for four consecutive years from 1997 to 2000 north of the Qinghai Lake. All three species, especially E. nutans, showed good adaptation to the dry and cold conditions of the test area. The seed of R. pauciflora and B. inermis could not ripen, but both of them, as well as E. nutans and the mixed pasture of the three species, had relatively high hay yields. In the second and third years, the hay yield of the mixed sward was significantly higher than the three single species swards, but this difference did not exist in the fourth year. In the mixed sward, competition among the three species was obvious, with E. nutans having the greatest competitive ability, followed by R. pauciflora and then B. inermis. The competition resulted in the proportion of E. nutans in the total yield increasing annually, while the other two declined. In the fourth year, B. inermis disappeared from the mixed pasture.