Crawford Kerri M, Knight Tiffany M
Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA.
Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204, USA.
Oecologia. 2017 Jan;183(1):211-220. doi: 10.1007/s00442-016-3759-2. Epub 2016 Oct 28.
Invasive plant species can modify soils in a way that benefits their fitness more than the fitness of native species. However, it is unclear how competition among plant species alters the strength and direction of plant-soil feedbacks. We tested how community context altered plant-soil feedback between the non-native invasive forb Lespedeza cuneata and nine co-occurring native prairie species. In a series of greenhouse experiments, we grew plants individually and in communities with soils that differed in soil origin (invaded or uninvaded by L. cuneata) and in soils that were live vs. sterilized. In the absence of competition, L. cuneata produced over 60% more biomass in invaded than uninvaded soils, while native species performance was unaffected. The absence of a soil origin effect in sterile soil suggests that the positive plant-soil feedback was caused by differences in the soil biota. However, in the presence of competition, the positive effect of soil origin on L. cuneata growth disappeared. These results suggest that L. cuneata may benefit from positive plant-soil feedback when establishing populations in disturbed landscapes with few interspecific competitors, but does not support the hypothesis that plant-soil feedbacks influence competitive outcomes between L. cuneata and native plant species. These results highlight the importance of considering whether competition influences the outcome of interactions between plants and soils.
入侵植物物种能够以一种对自身适合度的促进超过本地物种适合度的方式改变土壤。然而，尚不清楚植物物种之间的竞争如何改变植物 - 土壤反馈的强度和方向。我们测试了群落背景如何改变非本地入侵杂草楔叶胡枝子与九种同时出现的本地草原物种之间的植物 - 土壤反馈。在一系列温室实验中，我们将植物单独种植以及种植在群落中，所用土壤在土壤来源（被楔叶胡枝子入侵或未被入侵）以及土壤是活土还是灭菌土方面存在差异。在没有竞争的情况下，楔叶胡枝子在入侵土壤中产生的生物量比未入侵土壤中多60%以上，而本地物种的表现不受影响。无菌土壤中不存在土壤来源效应表明，积极的植物 - 土壤反馈是由土壤生物群的差异引起的。然而，在有竞争的情况下，土壤来源对楔叶胡枝子生长的积极影响消失了。这些结果表明，楔叶胡枝子在具有很少种间竞争者的干扰景观中建立种群时可能受益于积极的植物 - 土壤反馈，但并不支持植物 - 土壤反馈影响楔叶胡枝子与本地植物物种之间竞争结果的假设。这些结果突出了考虑竞争是否影响植物与土壤之间相互作用结果的重要性。
