Ventenata [Ventenata dubia (Leers) Coss.], an invasive winter annual grass, negatively impacts grassland community composition and function in the Pacific Northwest. Ventenata dubia established in Palouse prairie (PP) and canyon grasslands (CG) of northern Idaho/eastern Washington in the mid-1980s to early 1990s. Understanding and comparing patterns of invasion can elucidate future trends as its range expands. We performed surveys in PP (2012 and 2013) and CG (2018) to assess V. dubia abundance. Specifically, we correlated species richness, Shannon diversity, rank abundance, and indicator species with no, low (<12.5%), and high (>12.5%) V. dubia cover. We used nonmetric multidimensional scaling analysis (NMDS) to visualize species similarities and associations with abiotic variables. In both ecoregions, V. dubia was very common, appearing in nearly 60% of 450 plots. When present, V. dubia cover averaged 26% (±2.3 SE) in PP and 19% (±1.8 SE) in CG. Indigenous plant species richness and diversity were lowest in plots with high V. dubia cover. In CG, this relationship held for nonindigenous species; in PP, nonindigenous plant richness and diversity were higher with high V. dubia cover. Ventenata dubia and other winter annual grasses (Bromus spp., medusahead [Taeniatherum caput-medusae (L.) Nevski]) were moderately associated according to the NMDS analysis. Indicator species analysis showed V. dubia was positively associated with nonindigenous winter annual grasses and negatively associated with indigenous low shrub species. Abiotic factors that explained V. dubia abundance included shallow soils and a south to west aspect. Overall, these findings indicate V. dubia can successfully invade both dry and relatively wet plant communities and is more abundant than other invasive annual grasses. We suggest these findings foreshadow what will happen in sagebrush steppe and Great Plains grasslands, regions where V. dubia recently became established.

中文翻译：

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Ventenata dubia 30 年后入侵太平洋西北部束草群落的后果

文特纳塔 [狐臭(Leers) Coss.] 是一种侵入性的冬季一年生草，对太平洋西北部的草原群落组成和功能产生负面影响。狐臭1980 年代中期至 1990 年代初在爱达荷州北部/华盛顿东部的帕卢斯草原 (PP) 和峡谷草原 (CG) 建立。随着入侵范围的扩大，了解和比较入侵模式可以阐明未来趋势。我们在 PP（2012 年和 2013 年）和 CG（2018 年）中进行了调查，以评估五、杜比亚丰富。具体来说，我们将物种丰富度、香农多样性、等级丰度和指示物种与无、低 (<12.5%) 和高 (>12.5%) 相关联五、杜比亚覆盖。我们使用非度量多维尺度分析 (NMDS) 来可视化物种相似性和与非生物变量的关联。在这两个生态区，五、杜比亚非常普遍，出现在 450 个地块的近 60% 中。在场时，五、杜比亚PP 中覆盖率平均为 26% (±2.3 SE)，CG 中为 19% (±1.8 SE)。土着植物物种丰富度和多样性在高地块中最低五、杜比亚覆盖。在 CG 中，这种关系适用于非本土物种；在 PP 中，非本土植物丰富度和多样性较高五、杜比亚覆盖。狐臭和其他冬季一年生草（溴草spp., medusahead [水母带绦虫(L.) Nevski]) 根据 NMDS 分析中度相关。指标种类分析显示五、杜比亚与非本土冬季一年生禾草呈正相关，与本土低灌木物种负相关。解释的非生物因素五、杜比亚丰度包括浅层土壤和从南到西的方向。总的来说，这些发现表明五、杜比亚可以成功侵入干燥和相对潮湿的植物群落，并且比其他侵入性一年生草更丰富。我们认为这些发现预示了在艾草草原和大平原草原将发生的事情，这些地区五、杜比亚最近成立。