A native herbaceous community exerts a strong allelopathic effect on the woody range-expander Betula fruticosa

草本植物群落对灌木柴桦的范围扩张产生强烈的化感作用

Biological invasions by alien and range-expanding native plant species can suppress native plants through allelopathy.However,the homeland security hypothesis suggests that some native plants can resist invasion by producing allelopathic compounds that inhibit the growth of invasive plants.Most research has focused on allelopathic interactions between individual native and invasive plant species,with less emphasis on how allelopathy helps entire native communities resist invasions.Additionally,limited knowledge exists about allelopathic interactions between range-expanding native species and recipient native communities,and their influence on invasion success.To bridge this knowledge gap,we conducted two greenhouse competition experiments to test reciprocal allelopathic effects between a native woody range-expanding species,Betula fruticosa,and a community of four native herbaceous species(Sanguisorba officinalis,Gentiana manshurica,Sium suave and Deyeuxia angustifolia)in China.We assessed whether B.fruticosa and the native community differed in their competitive effects and responses,and whether these were influenced by activated carbon,which neutralizes allelochemicals in the soil.Activated carbon reduced the suppressive effects of the native community on the above-ground biomass of B.fruticosa,which indicates that the native community exerted a strong allelopathic effect on B.fruticosa.In contrast,activated carbon only marginally enhanced the suppressive effects of B.fruticosa on the native community,which indicates that allelopathy is not the primary mechanism by which B.fruticosa exerts its suppression.Overall,these findings support the homeland security hypothesis and suggest that biotic resistance from the native herbaceous community may limit the invasion success of the woody range-expander B.fruticosa.

外来植物物种的入侵和本土植物物种的范围扩张都可能通过化感作用抑制本土植物的生长。然而,国土安全假说表明,某些本土植物可以通过产生抑制入侵植物生长的化感物质来抵抗入侵。以往的研究大多数集中在个体本土和入侵植物之间的化感相互作用,对整个本土植物群落如何通过化感作用抵抗入侵的研究较少。此外,对于扩张范围的本地物种与接收地本地群落之间相互的化感作用及其对入侵成功的影响知之甚少。为此,我们开展了两项温室竞争实验,以测试一种本土的木本扩张物种柴桦(Betula fruticose)与4种本土草本植物种地榆(Sanguisorba officinalis)、东北龙胆(Gentiana manshurica)、泽芹(Sium suave)和小叶章(Deyeuxia angustifolia)组成的群落之间的相互化感作用。我们评估了柴桦和本土群落之间的竞争效应和响应的差异,以及这些差异是否受到活性炭添加的影响(活性炭添加可以中和土壤中的化感物质)。实验结果表明,活性炭的添加降低了本土植物群落对柴桦地上生物量的抑制作用,这表明本土植物群落对柴桦产生了强烈的化感作用。相比之下,活性炭添加仅轻微的增强了柴桦对本土植物群落的抑制作用,表明化感作用不是柴桦抑制本土植物群落生长的主要机制。总之,这些发现支持了国土安全假说,并表明本土草本植物群落的生物抵抗可能限制了木本范围扩张物种柴桦的入侵成功。