Testing for allelopathy in invasive plants: it all depends on the substrate!

Parepa, Madalin; Bossdorf, Oliver (2016). Testing for allelopathy in invasive plants: it all depends on the substrate! Biological invasions, 18(10), pp. 2975-2982. Kluwer 10.1007/s10530-016-1189-z

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Invasive plants can affect native plants through competition or allelopathy, and researchers often use pot experiments as a tool to measure the strength of these interactions. Recently, such pot experiments provided inconsistent estimates of the impact and allelopathic potential of invasive knotweed, one of the world's most successful plant invaders. We suspected that the inconsistencies may be explained by the use of different substrates in different experiments. To test this, we conducted an experiment in which knotweed competed pairwise with five common native European species in several different substrates: two compost-based potting substrates and two natural soils, with or without extra fertilizer added. To test for allelopathy, we added activated carbon to half of the pots. We found that knotweed was generally much more successful, and there was much more evidence for its allelopathy, when tested in artificial potting substrates than in natural soils. Furthermore, addition of extra fertilizer decreased the dominance of knotweed and changed patterns of allelopathy. The physicochemical properties of potting soil, such as lower bulk density, higher pore space, permeability and nitrogen content may better allow rhizomes to penetrate and/or allelochemicals to be produced and diffused. If artificial substrates generally exaggerate dominance and allelopathy also in other invasive plants, then many previous studies may have overestimated the potential impact of invaders, and the results of these experiments should be interpreted with caution. To avoid misleading results, experiments that test the competitive or allelopathic impact of invasive plants should be done with natural soils, preferably from the targeted habitats.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Plant Ecology
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

UniBE Contributor:

Parepa, Madalin and Bossdorf, Oliver


500 Science > 580 Plants (Botany)








Peter Alfred von Ballmoos-Haas

Date Deposited:

07 Oct 2016 12:33

Last Modified:

04 Sep 2018 12:47

Publisher DOI:


Uncontrolled Keywords:

Plant-plant interactions, Competition, Pot experiments, Fallopia, Reynoutria, Invasive knotweed





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