College of Landscape Architecture and Forestry, Qingdao Agricultural University, No. 700 Changcheng Road, Qingdao 266109, PR China; Academy of Dongying Efficient Agricultural Technology and Industry on Saline and Alkaline Land in Collaboration with Qingdao Agricultural University, Dongying 257347, PR. China.
Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao 266237, PR China.
Ecotoxicol Environ Saf. 2023 Jul 1;259:115029. doi: 10.1016/j.ecoenv.2023.115029. Epub 2023 May 20.
Nitrogen (N) deposition has increased dramatically in recent decades, which is significantly affecting the invasion and growth of exotic plants. Whether N deposition leads to invasive alien species becoming competitively superior to native species remains to be investigated. In the present study, an invasive species (Oenothera biennis L.) and three co-occurring native species (Artemisia argyi Lévl. et Vant., Inula japonica Thunb., and Chenopodium album L.) were grown in a monoculture (two seedlings of the same species) or mixed culture (one seedling of O. biennis and one seedling of a native species) under three levels of N deposition (0, 6, and 12 g∙m∙year). Nitrogen deposition had no effect on soil N and P content. Nitrogen deposition enhanced the crown area, total biomass, leaf chlorophyll content, and leaf N to phosphorus ratio in both invasive and native plants. Oenothera biennis dominated competition with C. album and I. japonica due to its high resource acquisition and absorption capacity (greater height, canopy, leaf chlorophyll a to chlorophyll b ratio, leaf chlorophyll content, leaf N content, leaf mass fraction, and lower root-to-shoot ratio). However, the native species A. argyi exhibited competitive ability similar to O. biennis. Thus, invasive species are not always superior competitors of native species; this depends on the identities of the native species. High N deposition enhanced the competitive dominance of O. biennis over I. japonica by 15.45% but did not alter the competitive dominance of O. biennis over C. album. Furthermore, N deposition did not affect the dominance of O. biennis or A. argyi. Therefore, the species composition of the native community must be considered when preparing to resist future biological invasions. Our study contributes to a better understanding of the invasion mechanisms of alien species under N-loading conditions.
氮（N）沉降在最近几十年中急剧增加，这显著影响了外来植物的入侵和生长。N 沉降是否会导致入侵的外来物种在竞争中优于本地物种，仍有待研究。在本研究中，以一种入侵物种（月见草）和三种共存的本地物种（艾草、野菊和藜）为研究对象，在三种氮沉降水平（0、6 和 12 g∙m∙year）下进行了单种培养（同一物种的两株幼苗）或混种培养（一株月见草幼苗和一株本地物种幼苗）。氮沉降对土壤 N 和 P 含量没有影响。氮沉降增加了入侵植物和本地植物的冠层面积、总生物量、叶片叶绿素含量和叶片 N 与 P 的比值。由于月见草具有较高的资源获取和吸收能力（更高的高度、冠层、叶片叶绿素 a 与叶绿素 b 的比值、叶片叶绿素含量、叶片 N 含量、叶片质量分数以及较低的根冠比），因此它在与藜和野菊的竞争中占据优势地位。然而，本地物种艾草表现出与月见草相似的竞争能力。因此，入侵物种并不总是优于本地物种的竞争者；这取决于本地物种的身份。高氮沉降增强了月见草对野菊的竞争优势，使其竞争优势提高了 15.45%，但没有改变月见草对藜的竞争优势。此外，氮沉降没有影响月见草或艾草的优势度。因此，在准备抵御未来生物入侵时，必须考虑本地群落的物种组成。本研究有助于更好地理解在氮负荷条件下外来物种的入侵机制。
