放牧强度对荒漠草原一年生植物刺穗藜种群特征及空间分布的影响

为探讨不同放牧强度下一年生植物种群特征及空间分布的变化特点及差异，本研究以内蒙古四子王旗短花针茅荒漠草原一年生植物刺穗藜（Chenopodium aristatum）为对象，分析了围封对照（CK）、轻度放牧（Light grazing）、中度放牧（Moderate grazing）和重度放牧（Heavy grazing）下刺穗藜种群特征（密度、单株重、株高、比叶面积、叶片/茎/根系干物质含量、叶片全碳、氮含量），种群变异性及其空间分布。结果表明：放牧显著影响刺穗藜种群密度（P<0.05），但对其比叶面积、叶片/根系干物质含量及叶片全碳、氮含量无显著影响；总体而言，放牧使刺穗藜种群密度增加，但对其种群性状影响较小；放牧使得刺穗藜种群相对密度增大（P<0.05），并造成其种群变异性降低（P<0.05）；对刺穗藜种群空间分布模拟发现，放牧使得刺穗藜种群空间分布均匀，空间异质性降低。在草地利用过程中，一年生植物种群特征及其空间分布可能对群落结构造成影响，对其进行相关研究很有必要。

Effects of Grazing Intensity on Population Characteristics and Spatial Distribution of the Annual Plant Chenopodium aristatum in the Desert Steppe

We conducted a grazing experiment to investigate the difference of population characteristics and spatial distribution of annual plant Chenopodium aristatum under different stocking rates in a Stipa breviflora desert steppe in Siziwang Banner,Inner Mongolia. The research objects,annual plant C. aristatum,its population characteristics (density,biomass per individual,plant height,specific leaf area,leaf-stem-root dry matter content,leaf total carbon,and leaf nitrogen content),population variability and the spatial distribution with four treatments (enclosure,light grazing,moderate grazing and heavy grazing) were analyzed. The results showed that,grazing significantly affected population density (P<0.05),but there had no significant effects on specific leaf area,leaf-root dry matter content,leaf total carbon or leaf nitrogen content among treatments. In general,grazing increased the population density,but did not change the population traits. Moreover,grazing increased the relative density of C. aristatum population but decreased its population variability (P<0.05). Finally,we simulated the spatial distribution of C. aristatum population and found that,grazing prompted the spatial distribution of C. aristatum population uniform and decreased spatial heterogeneity. In the process of grassland utilization,it is necessary to study the characteristics of annual plant population and its spatial distribution,which may affect the community structure.