草地群落物种多样性维持机制的研究Ⅱ物种实现的生态位

尽管为解释种类丰富的植物群落物种共存和多样性维持机制，生态学家位做了大量的努力并提出了许多假说和模型。但这一问题仍处在争议之中，需要更多的证据支持他们的观点或提出新的看法，使这一生物多样性难题不断地向前推进。以松赖平原物种丰富度较高的羊草－杂类草群落为对象，在土壤C、N、P、K和H2O等5个资源轴上，探讨了物种多样性与实现生态位的关系。结果表明：尽管物种生态位存在一定程度的分化，但多数物种的生态位是高度重叠的，物种生态位的分化在草地群落物种共存和多样性维持中，不是唯一的途径，认为应更加重视的物种在长期协同进化中所形成的生物学特性。

INVESTIGATING REALIZED NICHES AS A MECHANISM OF SPECIES DIVERSITY MAINTENANCE IN A SPECIES-RICH GRASSLAND COMMUNITY

Although ecologists have made great efforts and produced a large number of hypotheses and models attempting to explain species coexistence and the mechanisms of species diversity maintenance in plant communities, this problem remains unresolved. We investigate relationships between species diversity and the patterns of realized niche distribution of species along five soil resource gradients (C, N, P, K and H_2O) in a species-rich Leymus chinensis herb meadow community, on the Songnen Plain of Northeast China. The results showed that despite niche differentiation between species, the degree of niche overlap between species was high. We present a mechanism for coexistence deriving from small-scale pattern competition. However, we must conclude that niche differentiation cannot solely account for maintenance of species diversity in this grassland community, and that greater attention should be paid to the long-term co-evolution of species biological properties.