Invasive species alter ecosystem structure, impact biodiversity, and have significant economic costs. In Oregon's Willamette Valley, invasive grasses Arrhenatherum elatius and Schedonorus arundinaceus alter the dynamics of the phenologically paired interaction between an endangered butterfly, Icaricia icarioides fenderi (Fender's blue), and its larval host plant, Lupinus oreganus (Kincaid's lupine). To test methods to restore this interaction, we established a 3‐year experiment where a post‐emergent grass‐specific herbicide, fluazifop‐p‐butyl, was applied to Fender's blue habitat. Plant community data were recorded throughout the growing season at eight paired plots for 1 year prior to treatment and 3 years during treatment. We asked whether annual application of herbicide could reduce the height of invasive grasses to levels at or beneath the height of Kincaid's lupine racemes throughout the Fender's blue flight season. We hypothesized that native forb species, which are critical nectar sources for Fender's blue, would increase in cover and frequency following the release from competitive dominance of invasive grasses. Grass‐specific herbicide reduced grass height during the flight season of Fender's blue, but with several costs. We found no change in nectar and a suppression of lupine growth in plots in response to experimental herbicide treatment. Each study site had multiple secondary invaders; the long‐term impact of these new invaders is unknown. We suggest that herbicide application results in a net negative effect in the context of Fender's blue habitat restoration. That is, the costs to primary resources for Fender's blue and the influx of secondary invaders may be as problematic as the primary invasion by non‐native grasses.

中文翻译：

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以除草剂为基础的修复治疗对社区的影响：结构性好处，但付出了什么代价？

入侵物种改变了生态系统的结构，影响了生物多样性，并造成了巨大的经济损失。在俄勒冈州威拉米特河谷，侵入草燕麦草和Schedonorus茅改变物候配对相互作用的动力学濒临灭绝的蝴蝶之间，Icaricia icarioides fenderi（Fender的蓝色），其幼虫寄主植物，羽扇豆oreganus（金凯德的羽扇豆）。为了测试恢复这种相互作用的方法，我们建立了一个为期3年的实验，其中将出苗后的草专用除草剂fluazifop-p-butyl应用于Fender的蓝色栖息地。在治疗前1年和治疗期间3年的八个成对地块记录了整个生长季节的植物群落数据。我们询问了每年除草剂的使用是否可以将入侵草的高度降低到在Fender的蓝色飞行季节中，在Kincaid的羽扇豆消旋体的高度处或以下。我们假设原生的Forb物种是Fender's blue的重要花蜜来源，随着入侵草类竞争优势的释放，其覆盖率和频率会增加。在Fender的蓝色飞行期间，草专用除草剂降低了草的高度，但要付出一些代价。我们没有发现对试验性除草剂的处理能够引起花蜜的变化，并抑制了羽扇豆的生长。每个研究地点都有多个次要侵略者。这些新入侵者的长期影响尚不清楚。我们建议在Fender的蓝色栖息地恢复环境中使用除草剂会产生净负面影响。就是说，芬德蓝的主要资源成本和次要入侵者的涌入可能与非本地草类的主要入侵一样成问题。这些新入侵者的长期影响尚不清楚。我们建议在Fender的蓝色栖息地恢复环境中使用除草剂会产生净负面影响。就是说，芬德蓝的主要资源成本和次要入侵者的涌入可能与非本地草类的主要入侵一样成问题。这些新入侵者的长期影响尚不清楚。我们建议在Fender的蓝色栖息地恢复环境中使用除草剂会产生净负面影响。就是说，芬德蓝的主要资源成本和次要入侵者的涌入可能与非本地草类的主要入侵一样成问题。