区域尺度下黄背草种群空间分布格局及其与土壤因子的关系

Spatial distribution patterns of Themeda japonica populations and relationships with soil factors a regional scale

土壤因子是影响植物种群动态的主要环境因子之一,土壤理化性质在空间上的差异一定程度上决定着种群分布的空间差异。为了探究河南暖性草地优势植物黄背草(Themeda japonica)种群空间分布类型和规律,从土壤因子角度明确影响黄背草空间分布的因素,采用点面结合的方法,测度区域尺度上黄背草种群空间分布格局,并分析其与土壤因子的关系。结果表明,扩散系数(C)、丛生指标(I)、平均拥挤度(m*)与聚块性指数(PAI)等所表达的结果一致,即黄背草种群在河南不同区域空间分布类型均为聚集分布;同时,方差/均值比T检验、聚块性指数、Cassie指标(CA)和负二项参数(K)等的结果显示,黄背草种群在河南不同区域均呈现高度聚集分布格局。RDA冗余分析表明,豫北地区土壤因子对黄背草种群空间分布格局有显著影响的为土壤有机碳、土壤碳氮比和土壤pH(P <0.05),而豫西和豫南地区为土壤全磷(P <0.01)。对3个地区整体而言,土壤有机碳和土壤全磷与黄背草种群空间分布格局存在极显著相关性(P <0.01)。

Soil is a major environmental factor that affects plant population dynamics. Spatial variations in physical and chemical properties of soil determine, to some extent, the spatial differences of plant population distribution. To investigate the spatial distribution of populations of the dominant plant Themeda japonica in Henan grassland, the spatial distribution pattern of the T. japonica population was evaluated on a regional scale using the point-and-spot combination method, and the relationship between the distribution features and soil factors was analyzed. The diffusion coefficient (C), clumping index (I), mean crowding (m*), and patchiness index (PAI) indicated that T. japonica populations were distributed in clumped pattern in each region. In addition, the T-test of variance/mean ratio, patchiness index, Cassie index (CA), and negative binomial parameter (K) revealed that the T. japonica populations in different regions presented a highly aggregated distribution pattern. RDA redundancy analysis showed that the soil factors that significantly affected the spatial distribution pattern of T. japonica populations included soil organic carbon, soil carbon-nitrogen ratio, and soil pH values in northern Henan (P <0.05), while it was soil total phosphorus content (P < 0.01) in western and southern Henan. In general, there were significant correlations between soil organic carbon, soil total phosphorus, and the spatial distribution pattern of the T. japonica population (P < 0.01).