内蒙古中东部草原羊草群落种类组成及优势种种群数量特征的空间分异

Spatial Variation of Species Composition and Qualitative Characteristics of the Dominant Species among Different Leymus chinensis Communities in Mid-east Inner Mongolia Steppe.

比较研究了内蒙古中东部草原9个羊草群落的种类组成及优势种种群数量特征的空间变化。结果表明,随着水分自东向西减少,群落种类组成和优势种表现出地带性变化。在生境条件较好的地方,羊草群落的种类组成较复杂、种类较多,羊草的优势较明显;在生境条件较差的地方,羊草群落的种类组成较简单、种类较少,羊草的优势下降。同时,由于局部地形起伏导致水热条件的重新分配,群落种类组成和群落优势种表现出一定程度的非地带性。群落的相似性与其生境条件的相似性有关。羊草不同地理种群的数量特征也表现出一定的地带性变化,随着环境因子的变化特别是土壤水分的逐渐降低,羊草种群密度、生物量、优势度逐渐下降,羊草的生态位宽度相对较小,这是羊草种群在自然条件下的一种生态适应。

The species composition and the qualitative characteristics of the dominant species were compared among nine Leymus chinensis communities in Mid-east Inner Mongolia steppe.There existed great differences in qualitative characters and the distribution of L.chinensis in different communities.The results indicated that species composition and dominant species of the communities showed zonal changes with decreased moisture from east to west in the researched region:the better the habitats,the more complicated the composition of the L.chinensis communities and the more dominant L.chinensis.meanwhile,species composition and dominant species of the communities also showed azonal changes because of the influences of the local environment.Spatial variations were found in some qualitative characteristics among different L.chinensis populations--an important dominant species of the communities.The density, biomass and dominance index of L.chinensis decreased,the niche size decreased compared with the other dominant species, and its dominant position was gradually replaced by little bunch grasses with changed environmental factors,especially the decrease of soil water content,which may be an adaptive response in natural conditions.