Serrated tussock (Nassella trichotoma (Nees) Hack. ex Arechav) is an unpalatable grass species that has been expanding in its native range and invading non-native ranges. In this study in its natural environment, we aimed to describe the spatial relationship between seed density, the cover and density of standing individuals of serrated tussock, the seasonal variation in the seed density in the soil seed bank, and to compare these results with those reported in non-native ranges. We took soil samples seasonally and recorded the cover and density of standing individuals of serrated tussock at two sites in the native Pampas grasslands in central-east Argentina. Seed density was evaluated by seedling emergence and seed extraction. Seed density showed a seasonality trend, with maximum values in the end of summer and minimum values in winter and spring. Seed density was independent of the cover and density of standing individuals of serrated tussock. The values of seed density were lower than those reported in the invaded ranges. Since seeds of serrated tussock are present in the seed bank regardless of the cover and density of its standing individuals, the maintenance of a high cover of desirable species may play a key role in preventing the establishment of serrated tussock in both its natural and invaded ranges.

锯齿状的草s（Nassella trichotoma（需要）哈克。ex Arechav）是一种不宜食用的草种，其本地范围不断扩大，并侵入非本地范围。在自然环境下的这项研究中，我们旨在描述种子密度，锯齿状的站立个体的覆盖和密度，土壤种子库中种子密度的季节性变化之间的空间关系，并将这些结果与那些结果进行比较。报告在非本地范围内。我们按季节采集土壤样品，并记录了阿根廷中东部原生潘帕斯草原两个地点锯齿状tus的站立个体的覆盖率和密度。通过幼苗出苗和种子提取来评估种子密度。种子密度呈季节变化趋势，夏末最高，冬，春季最低。种子密度与锯齿状的站立个体的覆盖和密度无关。种子密度值低于入侵范围内的报告值。由于种子库中存在锯齿状tus的种子，而不管其站立个体的覆盖度和密度如何，因此，维持理想物种的高覆盖率可能在阻止其自然和入侵范围内锯齿状的建立方面发挥关键作用。