AUTHOR=Wu Hao , Dong Sijin , Wang Li , Zhu Yuanyuan , Jia Shaoqi , Rao Benqiang 

TITLE=Nitrogen enrichment alters the resistance of a noninvasive alien plant species to Alternanthera philoxeroides invasion

JOURNAL=Frontiers in Ecology and Evolution

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2023.1215191

DOI=10.3389/fevo.2023.1215191

ISSN=2296-701X

ABSTRACT=<p>Soil nitrogen can significantly affect the morphology, biomass, nutrient allocation, and photosynthesis of alien vs. native plants, thereby changing their coexistence patterns; however, the effect of soil nitrogen on the interspecific relationship between alien plants is currently unclear. We conducted a nitrogen addition experiment in a greenhouse to explore the effect of soil nitrogen on the interspecific relationship between invasive alien weed <italic>Alternanthera philoxeroides</italic> and the noninvasive alien horticultural plant <italic>Oxalis articulata.</italic> We set three experimental factors—nitrogen treatment, planting type, and species and measured the morphology, biomass, carbon (C) and nitrogen (N) content, physiological traits, and photosynthetic fluorescence of the studied plant species. We then used multi-way ANOVA and multiple comparisons to examine the differences in the above indicators among treatment combinations. We found that, in mixed cultures, nitrogen addition significantly increased the root area of <italic>O</italic>. <italic>articulata</italic> by 128.489% but decreased the root length by 56.974% compared with the control, while it significantly increased the root length of <italic>A</italic>. <italic>philoxeroides</italic> by 130.026%. Nitrogen addition did not affect the biomass accumulation of these two plant species; however, the biomass and root/shoot ratio of <italic>O</italic>. <italic>articulata</italic> were significant higher than those of <italic>A</italic>. <italic>philoxeroides.</italic> Nitrogen addition significantly increased the N content of <italic>A</italic>. <italic>philoxeroides</italic> by 278.767% and decreased the C:N ratio by 66.110% in mixed cultures. Nitrogen addition caused a significant trade-off between flavonoid and anthocyanin in <italic>O</italic>. <italic>articulata</italic>, and decreased the initial fluorescence (F<sub>0</sub>) and maximal fluorescence (F<sub>m</sub>) of <italic>A</italic>. <italic>philoxeroides</italic> by 18.649 and 23.507%, respectively, in mixed cultures. These results indicate that nitrogen addition increased the N absorption and assimilation ability of <italic>A</italic>. <italic>philoxeroides</italic> in deep soil; furthermore, it significantly enhanced the advantages for <italic>O</italic>. <italic>articulata</italic> in terms of morphology, physiological plasticity, and photosynthetic efficiency. In addition, <italic>O</italic>. <italic>articulata</italic> had better individual and underground competitive advantages. Under intensified nitrogen deposition, the biotic replacement effect of <italic>O</italic>. <italic>articulata</italic> on <italic>A</italic>. <italic>philoxeroides</italic> in natural ecosystems could be further enhanced.</p>