Ecological Botanical Gardens, BayCEER (Bayreuth Center for Ecology and Environmental Research), University of Bayreuth, Bayreuth, Germany.
Department of Animal Ecology 1, BayCEER (Bayreuth Center for Ecology and Environmental Research), University of Bayreuth, Bayreuth, Germany.
PLoS One. 2018 Nov 7;13(11):e0205843. doi: 10.1371/journal.pone.0205843. eCollection 2018.
Impacts of invasive species on native communities are often difficult to assess, because they depend on a range of factors, such as species identity and traits. Such context-dependencies are poorly understood yet, but knowledge is required to predict the impact of invasions.
We assessed species- and developmental stage-specificity of competitive and allelopathic effects of the invasive plant Impatiens glandulifera on different developmental stages of four native plant species. While some studies have shown a reduction in plant growth caused by I. glandulifera, the magnitude of its impact is ambiguous. For our study we used seedlings and juveniles of I. glandulifera and the native target species Geum urbanum, Filipendula ulmaria, Urtica dioica, and Salix fragilis (seedlings only of the latter), which often co-occur with I. glandulifera in different habitats. Plants were grown in competition with I. glandulifera or treated with I. glandulifera leaf material, or 2-metoxy-1,4-naphtoquinone (2-MNQ), its supposedly main allelochemical.
Overall I. glandulifera had a negative effect on the growth of all target species depending on the species and on the plant's developmental stage. F. ulmaria was the least affected and U. dioica the most, and seedlings were less affected than juveniles. The species-specific response to I. glandulifera may lead to an altered community composition in the field, while growth reduction of seedlings and juveniles should give I. glandulifera an advantage in cases where plant recruitment is crucial. 2-MNQ led to minor reductions in plant growth, suggesting that it may not be the only allelopathic substance of I. glandulifera. Surprisingly, I. glandulifera was not fully tolerant to 2-MNQ. This autotoxicity could contribute to I. glandulifera population dynamics. We conclude that I. glandulifera reduces the growth of native vegetation and alters early successional stages without fully hindering it.
入侵物种对本地群落的影响通常难以评估，因为它们取决于一系列因素，如物种身份和特征。然而，这些背景依赖性的知识还没有被充分理解，但为了预测入侵的影响，这些知识是必需的。
我们评估了入侵植物硬骨凌霄（Impatiens glandulifera）对四种本地植物物种不同发育阶段的种和发育阶段特异性竞争和化感作用。虽然一些研究表明硬骨凌霄会导致植物生长减少，但它的影响程度尚不清楚。在我们的研究中，我们使用了硬骨凌霄的幼苗和幼株以及本地目标物种欧洲婆婆纳（Geum urbanum）、费菜（Filipendula ulmaria）、荨麻（Urtica dioica）和欧洲山柳（Salix fragilis）（仅后者的幼苗），这些物种通常与硬骨凌霄在不同的栖息地共同出现。植物与硬骨凌霄竞争生长或用硬骨凌霄叶片材料或 2-甲氧基-1,4-萘醌（2-MNQ）处理，2-MNQ 是其假定的主要化感物质。
总体而言，硬骨凌霄对所有目标物种的生长都有负面影响，具体取决于物种和植物的发育阶段。费菜受影响最小，荨麻受影响最大，幼苗受影响小于幼株。对硬骨凌霄的种特异性反应可能导致在野外改变群落组成，而幼苗和幼株生长的减少应使硬骨凌霄在植物繁殖至关重要的情况下具有优势。2-MNQ 导致植物生长略有减少，表明它可能不是硬骨凌霄的唯一化感物质。令人惊讶的是，硬骨凌霄对 2-MNQ 不完全耐受。这种自毒性可能有助于硬骨凌霄种群动态。我们的结论是，硬骨凌霄会降低本地植被的生长，并改变早期演替阶段，而不会完全阻碍其生长。
