Abstract: Point pattern analysis is often used to explain the relationship between the spatial distribution pattern of populations and the environment and ecological processes at different scales, but currently there is a lack of in-depth and systematic understanding of the spatial distribution pattern of species under the influence of slope position in meadow grassland. Therefore, Inner Mongolia mountain meadow grassland was selected as the research object to investigate the spatial distribution pattern and correlations of the dominant species of Leymus chinensis and the companion species of Carex leiorhyncha in the three slope positions by using the statistical method of g(r) function of the point pattern analysis and three kinds of null models. The results showed that the populations of L. chinensis and C. leiorhyncha showed a tendency of aggregated distribution at different slopes, which gradually changed to random and uniform distribution with the increase of scale. The aggregation degree was the largest in the lower slope, and the aggregation effect was gradually decreased with the increase of the slope. All the populations of L. chinensis and C. leiorhyncha at all slopes basically conformed to the heterogeneous Poisson model and the Poisson cluster model, which means that habitat heterogeneity and dispersal limitation significantly affected population spatial distribution patterns. Significant positive associations were found between the downslope populations of L. chinensis and C. leiorhyncha, while the associations between the upslope and mid-slope populations of Leymus chinensis and Carex leiorhyncha were mainly negative and non-correlated. The results of this study can provide a reference basis for understanding the structure and function of meadow grassland communities in Inner Mongolia.

Key words: Leymus chinensis, Carex leiorhyncha, Null model, Slope position, Spatial distribution pattern

摘要： 点格局分析常用来解释不同尺度上种群空间分布格局与环境的关系及生态学过程，但当前对草甸草原坡位影响下的物种空间分布格局还缺乏深入系统的认识。因此，本研究选取内蒙古科右前旗山地草甸草原为研究对象，通过点格局分析的g(r)函数统计方法和3种零模型，探究三个坡位群落优势种羊草(Leymus chinensis)和伴生种尖嘴薹草(Carex leiorhyncha)的空间分布格局及种间关联性。结果表明羊草和尖嘴薹草种群在不同坡位均呈现出先聚集分布，随尺度增加逐渐转变为随机分布和均匀分布的趋势。在下坡位尖嘴苔草聚集程度最大，随着坡位的升高聚集效应逐渐减弱。各坡位羊草和尖嘴薹草种群都基本符合异质泊松模型和泊松聚块模型，即生境异质性和扩散限制显著影响种群空间分布格局。下坡位的羊草和尖嘴薹草种群间存在显著的正关联，而上坡位和中坡位的羊草和尖嘴薹草种群的种间关联基本表现为负关联和无关联。研究结果可为深入理解不同坡位内蒙古山地草甸草原群落结构和功能提供参考依据。

关键词: 羊草, 尖嘴薹草, 零模型, 坡位, 空间分布格局