摘要:植物种群的空间分布格局及其关联性不仅反映种群的生态调控能力和环境可塑性机制，也是其在群落中地位与生存能力的外在表现。在宁夏盐池县，选择以蒙古冰草为优势种的荒漠草原为对象，按丛径将蒙古冰草个体划分Ⅰ级株丛（0-5 cm）、Ⅱ级株丛（5.1-10 cm）、Ⅲ级株丛（10.1-15 cm）、Ⅳ级株丛（15.1-20 cm）和Ⅴ级株丛（>20 cm）5个株丛级，采用点格局分析中的O-ring函数统计方法，分析了蒙古冰草种群的株丛结构、各级株丛的空间分布格局及关联性。结果表明：（1）蒙古冰草种群中Ⅰ、Ⅱ级株丛占比（79.24%）明显高于Ⅳ、Ⅴ级株丛占比（8.46%），种群中可供更新的幼苗充足，种群表现出良好的发展趋势。（2）在小尺度范围内，蒙古冰草Ⅰ、Ⅱ、Ⅲ级株丛主要表现为聚集分布，而且个体越小聚集程度越高，随尺度的增大，逐渐过渡到随机分布和均匀分布，Ⅳ、Ⅴ级株丛在所有尺度上均为随机分布。（3）蒙古冰草种群Ⅰ级株丛与Ⅱ、Ⅲ级株丛，Ⅱ级株丛与Ⅲ级株丛在小尺度内呈显著正关联，随研究尺度的增大趋于无关联，其余各级株丛在0-5 m尺度上主要呈无关联。



Abstract:Agropyron mongolicum is the dominant species in desert steppe in Ningxia, China. With strong drought resistance, cold endurance, and wind and sand tolerance characteristics, A. mongolicum plays important roles in soil and water conservation, agricultural production, and ecological restoration. The spatial distribution pattern and association of plant population not only reflect the ecological regulation ability and environmental plasticity mechanism of a population, but also the external manifestation of their status and viability in the community. To clarify the spatial distribution pattern and association of A. mongolicum at different developmental stages, a desert steppe dominated by A. mongolicum in Yanchi, Ningxia was selected as the research object. The spatial coordinates and diameter of individual clusters of A. mongolicum were measured with a 10 m×10 m sample plot. Five cluster degrees consisting of Ⅰ degree cluster (0-5 cm), Ⅱ degree cluster (5.1-10 cm), Ⅲ degree cluster (10.1-15 cm), Ⅳ degree cluster (15.1-20 cm), and Ⅴ degree cluster (>20 cm) were classified according to the individual cluster diameter. Based on the data from the sample plot, the spatial distribution pattern and association of A. mongolicum among different degree clusters were analyzed by adopting the method of point pattern analysis and O-ring function statistic. The results showed that the proportion of Ⅰ and Ⅱ degree clusters was significantly higher than that of Ⅳ and Ⅴ degree clusters in A. mongolicum population, accounting for 79.24% of the total population. The population had adequate regenerative seedlings and exhibited good development trend. The Ⅰ, Ⅱ, and Ⅲ degree clusters mainly aggregated in a small spatial scale, and the aggregation degree strengthened with the decrease in individuals. As the scale increased, the aggregation degree decreased and gradually transformed to random and uniform distribution. The Ⅳ and Ⅴ degree clusters of A. mongolicum appeared as random distribution at all scales. The association between Ⅰ and Ⅱ degree clusters, Ⅰ and Ⅲ degree clusters, and Ⅱ and Ⅲ degree clusters of A. mongolicum showed significant positive relationship at a small scale, and tended to be unassociated with increase in scale. The remaining cluster levels showed no association at the 0-5 m scale.





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