Abstract Facilitation may contribute to conserving natural systems disturbed by humans. We hypothesized that the unpalatable native weed, Baccharis ulicina (Baccharis) protects palatable plants from cattle grazing in central Argentina grasslands. We tested this hypothesis through observational and experimental studies. In the observational study, we compared consumption and performance of plants growing in Baccharis and Baccharis-free (open) microsites. We also recorded photosynthetically active radiation, soil moisture, and total soil nitrogen (N) in both microsites. In the experiment, we removed Baccharis aboveground biomass and compared herbivory and plant performance in Baccharis, Baccharis-removed, and open microsites. Palatable plants were less consumed when growing with than without Baccharis, and palatable grasses with the highest forage values were more abundant, taller, and fecund in Baccharis than open microsites in our observational study. Additionally, except for increased radiation in the open, there were no differences in abiotic variables between microsites. Results from the plant removal experiment were consistent with those from the observational study and did not offer evidence for direct facilitation. We conclude that protection from cattle is an important mechanism through which Baccharis benefits neighboring plants. Our work emphasizes the need to recognize the facilitative role of weeds in the management of semi-arid grasslands.

中文翻译：

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本地杂草保护在半干旱天然草原养牛的物种

摘要 便利化可能有助于保护受人类干扰的自然系统。我们假设难吃的本地杂草 Baccharis ulicina (Baccharis) 保护可口的植物免受阿根廷中部草原的牛群放牧。我们通过观察和实验研究检验了这一假设。在观察性研究中，我们比较了在 Baccharis 和无 Baccharis（开放式）微型站点中生长的植物的消耗量和性能。我们还记录了两个微型站点的光合有效辐射、土壤水分和土壤总氮 (N)。在实验中，我们去除了 Baccharis 地上生物量，并比较了 Baccharis、去除 Baccharis 和开放微型场地的食草和植物性能。与没有 Baccharis 的情况相比，可口的植物在生长时消耗更少，在我们的观察性研究中，Baccharis 中具有最高草料价值的可口草比开放的微型场地更丰富、更高、更肥沃。此外，除了露天辐射增加外，微型站点之间的非生物变量没有差异。植物移除实验的结果与观察性研究的结果一致，并没有提供直接促进的证据。我们得出结论，保护牛是 Baccharis 使邻近植物受益的重要机制。我们的工作强调需要认识到杂草在半干旱草原管理中的促进作用。微型站点之间的非生物变量没有差异。植物移除实验的结果与观察性研究的结果一致，并没有提供直接促进的证据。我们得出结论，保护牛是 Baccharis 使邻近植物受益的重要机制。我们的工作强调需要认识到杂草在半干旱草原管理中的促进作用。微型站点之间的非生物变量没有差异。植物移除实验的结果与观察性研究的结果一致，并没有提供直接促进的证据。我们得出结论，保护牛是 Baccharis 使邻近植物受益的重要机制。我们的工作强调需要认识到杂草在半干旱草原管理中的促进作用。