放牧和围封对赖草草地群落空间分布特征的影响

Effects of Grazing and Enclosure on Spatial Distribution Characteristics of Leymus secalinus Communities

为明确赖草草地群落对不同放牧管理方式的响应,在长期放牧和围封条件下,对其空间格局异质性进行了研究。结果表明:经过6年的围栏封育,草地群落高度、盖度和地上生物量显著增加,放牧样地优势度指数和多样性指数显著低于围封样地,群落组分种的重要值也发生不同程度的变化;物种的多度等级分布格局在放牧样地符合对数正态分布模型和Zipf-Mandelbrot模型,而在围封样地符合生态位优先占据模型;放牧样地赖草空间变异主要由放牧家畜的选择性采食和践踏等随机因素引起;围封样地结构性因素引起的异质性占有较大的比重,群落空间分布格局简单,导致赖草单顶级群落趋于稳定。因此,建议对赖草草地采用适度放牧和短期围栏相结合的利用方式,这对维持草地生物多样性具有重要意义。

The grassland of Leymus secalinus communities were taken as research object ,the spatial distribution pat‐terns and characteristics of main plant populations were investigated in grazed and enclosed plots after six‐year enclo‐sing with the help of the ground statistical analysis .Results showed that enclosure has significantly positive effects on vegetation cover ,height and the above‐ground biomass ,however ,it has significantly negative effects on dominance in‐dex and diversity index compared with those in grazed plots .The important values of component species of L .secalinus communities were changed in different degrees ,and the species‐abundance distribution pattern was log‐normal model and Zipf‐Mandelbrot model in grazed plot ,but the niche preemption model was the best‐fit model in enclosed plot .Spa‐tial variability of L .secalinus population caused by random factors such as selective feeding and trampling behavior of grazing animal in enclosed plot ,however ,structural factors cause the heterogeneous distribution of L .secalinus popu‐lation in grazing plot .According to our results ,the population of L .secalinus in enclosed area became more stable without interference .We suggest that the combination of the short‐term enclose and grazing was the effective way to maintain the biodiversity of salinization grasslands .