Numerous pressures influence the ecological capacity and health of drylands globally. Shrubs are often a critical component of these systems and can function positively as foundation species through facilitation of other species. Nonetheless, limited attention has been paid to the potential negative and indirect effects of shrubs. Here, we tested the hypothesis that plant facilitation can both accelerate the invasion process and amplify the negative effects of an invader on the native community. The invasive species Bromus madritensis ssp. rubens capitalized on facilitation by resident native shrub species. This in turn further degraded California mixed grasslands by negatively impacting other annual protégé plant species in these specific microhabitats. Indirect shrub-mediated interactions were thus a critical component of the ecological community assembly processes, and this suggests that we need to move beyond pairwise interactions to more rapidly advance grassland management and restoration theory.

中文翻译：

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促进促进植物入侵和间接负面相互作用

许多压力影响着全球旱地的生态容量和健康。灌木通常是这些系统的重要组成部分，并且可以通过促进其他物种作为基础物种发挥积极作用。尽管如此，人们对灌木潜在的负面和间接影响的关注有限。在这里，我们测试了植物促进既可以加速入侵过程又可以放大入侵者对本地社区的负面影响的假设。入侵物种Bromus madritensis ssp。鲁本斯利用本地本地灌木物种的便利。这反过来又通过对这些特定微生境中的其他一年生保护植物物种产生负面影响，进一步退化了加利福尼亚混合草原。因此，间接灌木介导的相互作用是生态群落组装过程的关键组成部分，这表明我们需要超越成对相互作用，以更快地推进草地管理和恢复理论。