Plant invaders often exhibit substantially higher productivity than the communities they replace. However, little is known about interactions among invaders and microbial decomposers responsible for converting organic nutrients into plant-available forms to fuel this productivity. We performed two laboratory incubations with soil and plant material collected from five-year-old experimental plantings to assess if four grassland invaders (Bromus tectorum, Centaurea stoebe, Euphorbia esula and Potentilla recta) or native plant mixtures (including Pseudoroegneria spicata and Penstemon strictus) changed microbial community composition and function (experiment 1), and if plant-derived dissolved organic matter (DOM) contributed to these changes (experiment 2). We measured respiration responses throughout the 39-day incubations and assessed soil bacterial communities with 16S rRNA high-throughput sequencing at 0 and 48 h. Overall, we found bacterial community composition and function differed among plant communities. Two invaders in particular, B. tectorum and E. esula, generated dissimilar DOM with corresponding differences in bacterial composition and function. Soil bacteria accustomed to B. tectorum DOM (high carbon to nitrogen, C:N) harbored more oligotrophs and generated slow but large cumulative responses to a resource pulse. By contrast, soil bacteria accustomed to E. esula DOM (low C:N) harbored more copiotrophs and generated quicker respiration responses. Finally, we found a single pulse of invader-derived DOM shifted bacterial composition in soil associated with native plants. Our findings indicate invaders can differ substantially in interactions with microbial decomposers and these differences are, at least in part, driven by differences in DOM. While increased productivity and accelerated nutrient cycling may be common across invaders, our findings indicate that the underlying mechanisms driving these increases may be specific to each invader.

植物入侵者通常比其所取代的社区表现出更高的生产力。但是，对于入侵者和微生物分解者之间的相互作用知之甚少，这些入侵者负责将有机养分转化为植物可用的形式以促进这种生产力。我们进行了两次实验室孵化，对从五年历史的实验性种植中收集的土壤和植物材料进行了评估，以评估是否有四个草原入侵者（凤尾麦，半人马，大戟大戟和委陵菜）或原生植物混合物（包括假单胞菌和严格的Penstemon菌））改变了微生物群落的组成和功能（实验1），以及植物来源的溶解性有机物（DOM）是否促成了这些变化（实验2）。我们在整个39天的孵育过程中测量了呼吸反应，并在0和48小时使用16S rRNA高通量测序评估了土壤细菌群落。总体而言，我们发现植物群落之间的细菌群落组成和功能有所不同。特别是两个入侵者，B. tectorum和E. esula，产生异种DOM与对应于细菌组成和功能的差异。习性土壤杆菌的土壤细菌DOM（高碳比氮，C：N）具有更多的寡营养生物，对资源脉冲产生缓慢但较大的累积响应。相比之下，习惯于大肠埃希氏菌DOM（低C：N）的土壤细菌具有更多的营养生物，并产生更快的呼吸反应。最后，我们在与原生植物相关的土壤中发现了一个由入侵者衍生的DOM转移的细菌组成的单一脉冲。我们的发现表明，入侵者与微生物分解剂的相互作用可能存在显着差异，并且这些差异至少部分是由DOM差异驱动的。虽然提高生产率和加快养分循环在侵略者中很常见，但我们的发现表明，推动这些增加的潜在机制可能对每个侵害者都是特定的。