Bidens frondosa

In summary, our experimental findings suggest that the reproductive traits, such as the versatile mating system of self- and cross-pollination, high seed production, a special method of achene dispersal and germination peak, accompanied by a high accumulated germination rate, might contribute to the invasive ability of B. frondosa. Meanwhile, allelopathic inhibition (Yan et al. 2012) and few natural enemies (Han et al. 2009) would also enhance its ability to adapt or compete, and thus improve its ability to invade. (Yan et al. 2016)

All leaching liquors of organs suppressed the seed germination of the native species Geum japonicum var. chinense and reduced the final germination percentage and rate, and increased the germination inhibition rate, with a bimodal dependence on concentration. (Wang et al. 2014)

Since it has been recorded that the invasive B. frondosa plant competes and often displaces native species, namely, B. tripartita L. and B. radiata Thuill., in naturalization sites (Gruberova and Prach, 2003; Vasil’eva and Papchenkov, 2011; Vinogradova et al., 2013), a comparative analysis of the biological features of these species is performed. (Ronzhina, 2017)

Vasilyeva and Papchenkov (2011) observed that B. frondosa could result in the elimination of local B. tripartita L. populations and reductions in B. radiata Thuill. populations through hybridization. (Pan et al. 2016)

The competitiveness of invasive B. frondosa was studied previously (Vinogradova 2010). Comparison of species in mixed plantings showed that invasive B. frondosa had a competitive advantage over native B. tripartita in terms of seed germination, growth rate, biomass, and seed production, and it is able to displace B. tripartita on soils of different fertility (at both high, average, and low contents of nutrients) and water regime. (Galkina et al. 2015)

Longterm (2002–2010) stationary observations on the populations of invasive North American Bidens frondosa L. and indigenous Bidens species were carried out on the banks of Kuibyshev, Cheboksary, and Gorky reservoirs. It was found that, during the invasion of B. frondosa into the biota, its populations, as well as the populations of indigenous Bidens species, underwent significant changes caused by an active natural hybridization and resulting in the vanishing of a local B. tripartita species, reduction of the B. radiata population, and the formation of a new form of alien B. frondosa. (Vasilyeva & Papchenkov 2011)

The results showed that the competitive response of B. frondosa declined with nutrient increment, while that of B. tripartita increased. Furthermore, the competitive response of B. frondosa was greater than that of B. tripartita under low nutrient level and on the contrary under high nutrient level. The growth of B. frondosa was suppressed by competitor under low nutrient, while did that of B. tripartita under high nutrient. Therefore, it was suggested that the competitive ability of B. frondosa was enhanced with nutrient increasing, meanwhile that of B. tripartita decreased. Human activities cause nutrient increase, which increase the competitive capacity of B. frondosa to B. tripartita, and then improved the exotic species invasion.