呼伦贝尔草甸草原物种多度分布格局

Plant species abundance distribution patterns in Hulunbuir meadow steppe

以内蒙古呼伦贝尔草甸草原为研究对象,通过野外调查,采用数学模型分析了利用方式对草地植物群落物种多度分布格局的影响。通过利用具有不同生态学意义的数学模型拟合草甸草原植物群落在不同生态学过程下物种的真实分布,并利用卡方(χ~2)、赤池信息准则(AIC)和贝叶斯信息准则(BIC)进行检验,从而揭示草地利用方式与植物群落结构的关系。结果表明:放牧、割草和围封草地物种多度分布最优拟合模型均为断棍模(BSM)。放牧利用方式下χ~2=92.99,AIC=373.58,BIC=378.49;刈割利用方式下χ~2=98.51,AIC=307.76,BIC=312.67;围封下χ~2=186.57,AIC=303.13,BIC=307.53。生态位重叠模型(ONM)对放牧利用草地的拟合结果也可以被接受(χ~2=422.69,AIC=409.25,BIC=414.16),但较断棍模型(BSM)效果差;生态位重叠模型(ONM)、生态位优先占领模型(NPM)和随机分配模型(RAM)的吻合度差距较大。采用多种模型和检验方法综合分析草地群落内、外因素变化,有助于深入理解群落变化的生态过程。

Based on field survey,plant species abundance distributions under different utilization modes of the Hulunbuir meadow steppe were analyzed by mathematical models.The purpose o4 this study is to use mathematical models with different ecological significanees to fit the true distribution of plant species under different ecological processes in meadow steppe.Chi-square(X2),Akaike information criterion (AIC)and Bayesian information criterion (BIC)were used for verification.The results showed that the best fitting model of species abundance distribution in grazing,clipping,and enclosing grasslands was the broken stick model (BSM),with χ^2= 92.99,AIC =373.58,and BIC =378.49for grazing grassland;χ^2=98.51,AIC =307.76,and BIC =312.67for clipping grassland ;χ^2=186.57,AIC =303.13,and BIC =307.53for enclosing grassland.The fitting results of the niche overlap model (ONM)could also be accepted (χ^2= 422.69,AIC =409.25,BIC =414.16)in grazing grassland,but the effect was worse than that of BSM.Meanwhile,there were great differences in fitness among ONM,niche-predominance model (NPM)and random allocation model (RAM).Our results indicated that the application of multi- ple SDP models and verification methods would be beneficial to select the best model and better understand the ecological processes of grassland community under different utilization regimes.