Data product for "Nitrogen level and legume presence affect competitive interactions between a native and invasive grass"

We conducted a greenhouse experiment to investigate effects of the native N2-fixing legume, L. argenteus, on competitive interactions between seedlings of the non-native annual grass, B.tectorum, and a native perennial grass, E. multisetus, over a gradient of nitrogen (N) availability. The experiment consisted of three levels of N (0, 5mM and 20mM N, where mM = millimolar = millimoles per liter), two levels of target species (Bromus or Elymus) and three levels of competitor (Lupinus, Bromus, or Elymus).Within each treatment we measured tiller production, aboveground biomass, and tissue carbon (C) and N of target species. Potassium chloride (KCl) extractable soil N also was measured within each treatment.Increased resource availability often promotes expansion of invasive species by changing competitive interactions. N2-fixing species are often abundant in nitrogen (N) poor systems, and have the capacity to alter resource availability, particularly N, and, thus, to indirectly influence competitive interactions. Like many arid areas dominated by perennial grasses, the sagebrush steppe of the western U.S. is threatened by invasion of non-native species, especially annual grasses. N2-fixing legumes are common, and are often used in restoration, but have the potential to facilitate invasion and expansion of invasive annual grasses. The presence of Lupinus was facilitative for Bromus but indirectly inhibitory for Elymus. Our results indicate that modification of the local resource pool by Lupinus can alter competitive outcomes among this native and non-native species and can provide an avenue for expansion of non-native B. tectorum.Original metadata date was 05/14/2009. Metadata modified on 03/19/2013 to adjust citation to include the addition of a DOI (digital object identifier) and other minor edits. Minor metadata updates on 12/20/2016.本研究开展温室盆栽实验，旨在探究本土固氮豆科植物银叶羽扇豆（L. argenteus）在氮（N）有效性梯度下，对非本土一年生草本旱雀麦（B. tectorum）与本土多年生草本多穗偃麦草（E. multisetus）幼苗间种间竞争关系的影响。实验设置3个氮素水平（0、5mM及20mM N，其中mM即毫摩尔浓度，单位为毫摩尔每升）、2个目标物种组（雀麦属或偃麦草属），以及3个竞争者组（羽扇豆属、雀麦属或偃麦草属）。每个处理组中，我们测定了目标物种的分蘖数、地上生物量及组织碳（C）和氮（N）含量；同时测定了各处理组内的氯化钾（KCl）浸提态土壤氮含量。 资源可获得性提升通常会通过改变种间竞争关系，促进入侵物种的扩张。固氮物种常富集于氮素匮乏的生态系统中，具备改变资源可获得性（尤其是氮素）的能力，进而间接影响种间竞争关系。与诸多以多年生草本为主的干旱区域类似，美国西部的艾灌丛草原（sagebrush steppe）正受到非本土物种（尤其是一年生草本）入侵的威胁。固氮豆科植物在此区域分布广泛，且常被用于生态修复，但它们也有可能促进入侵性一年生草本的入侵与扩张。 实验结果显示，羽扇豆属植物对旱雀麦具有促进作用，却对多穗偃麦草产生间接抑制效果。本研究结果表明，羽扇豆属植物对本地资源库的改造能够改变本土与非本土物种间的竞争结局，为非本土旱雀麦的扩张提供了可行途径。 原始元数据日期为2009年5月14日。2013年3月19日对元数据进行修订，调整了参考文献以添加数字对象标识符（DOI）并完成其他小幅编辑。2016年12月20日对元数据进行了小幅更新。