Allelopathic and Competitive Interactions Between Native and Alien Plants

Abstract

The novel-weapons and homeland-security hypotheses are based on the idea that aliens and natives are not adapted to each other’s allelochemicals as they did not co-evolve. However, as only a few studies have tested this, it remains unclear how important co-evolutionary history is in determining the strength of allelopathic interactions between aliens and natives. Here, we tested for potential pairwise allelopathic effects on each other of five alien and five native herbaceous species in China. We did a germination and a competition experiment. In the germination experiment, we tested whether aqueous extracts of the ten study species had allelopathic effects on each other’s seed germination. In the competition experiment, we tested whether the alien and native species differed in their competitive effects and responses, and whether these were changed by the presence of activated carbon –a presumed allelopathy neutralizer– in the soil. Plant extracts had negative allelopathic effects on seed germination. This was particularly the case for extracts from the native species. Moreover, aqueous extracts had slightly stronger negative effects on germination of the aliens than on germination of the natives. In the competition experiment, on the other hand, the natives suffered more from competition than the alien species did, but we could not relate this to allelopathy. Alien plants had negative competitive and allelopatic effects on native plants, and the reverse was also true. These alien-native interactions, however, were not consistently stronger or weaker than native-native interactions or alien-alien interactions.

The other way around: the utility of a plant invader

“…Additionally, AC may display other side effects, such as the reduction of mycorrhiza infection or the stimulation of microbial community (Weißhuhn and Prati, 2009). Also, a clear negative effect of AC on plant biomass and survival was also reported in a previous study (Yuan et al ., 2021). Although AC was proven to be valid in allelopathic studies by blocking allelopathic effects (e.g., Sturm et al ., 2018; Kheirabadi et al ., 2020; Lorenzo et al ., 2021), experimental designs as the one used in this study must allow the identification of possible isolated and interactive effects of AC on target plants.…”

Interactive effects of allelopathy and arbuscular mycorrhizal fungi on the competition between the invasive species Bidens alba and its native congener Bidens biternata

“…This study provides evidence that both allelopathy and AMF are major components of feedback effects on plant invasion and that their interaction plays an important role in the competition between invasive and native species. Activated carbon is usually used to reduce allelopathic potential in soil (Yuan et al, 2021), whereas it influences the soil nutrients and plant growth in some circumstances (Lau et al, 2008). It should be noted that AC had no significant effect on soil N and P in the present study (Table S1), implying that the effects of AC addition on soil nutrients are minimal.…”

Nitrogen Deposition Elevated the Allelopathic Effects of Three Compositae Invasive Species on Indigenous <i>Lactuca sativa</i>

“…Canadensis is prosperous and can form an underground density system. Therefore, many allelochemicals release into the surrounding environment and inhibit the growth of other species [40,41]. The high concentration of E. canadensisi aqueous extract can significantly reduce the radicle length of Brassica pekinensis L., Cichorium endivia L., and Daucus carota L. Still, the effects were not obvious or even promoted at low concentrations.…”