美国俄勒冈州西南部的山麓牧场和草地,由于过度放牧而使一年生牧草占优势,如水母头滨麦,刺洋狗尾草,鳞茎早熟禾,直梗雀麦和各种一年生双子叶草类包括黄色星蓟(Centaurea solstialis)。曾试图在这些地区通过减轻放牧压力或播种,以恢复有价值的多年生饲草种类。然而,这些方法的费用很高。 The foothills and pastures of southwestern Oregon, USA, predominate annual grasses due to overgrazing such as the jellyfish head prickly ash, prickly wire, bluebell, cuttleweed and various annual dicotyledons including the yellow star Thistle (Centaurea solstialis). There have been attempts to restore valuable perennial forage species in these areas by reducing grazing pressure or sowing. However, these methods are expensive.