Impact of Ambrosia trifida on the soil seed bank
Ambrosia trifida (Asteraceae – EPPO A2) is native to North America, where it is recorded as weedy in many States or Provinces. It was introduced into the EPPO region at the end of the 19th century, and it has expanded its range since the mid-1900s. In the Yili Valley, Xinjiang, China, A. trifida was first reported in the Nalati grassland in 2010. By 2020, the area the species occupies had expanded 3113-fold, reaching 37 900 ha. After 4–5 years of unimpeded invasion, a single dense stand had formed over the area with nearly 100 % population coverage. The soil seed bank in the grassland was studied over eight years following A. trifida invasion and again after its removal. The results showed that four years after the invasion, the seed bank density of the native plant community decreased by 30 %, while the percentage cover of A. trifida aboveground reached 83%. The species richness in the seed bank also decreased and was the lowest when the percentage cover of A. trifida was 100 %, six years after the invasion. Eight years after the invasion, the seed bank density and species richness of the native community decreased by 83 % and 39 %, respectively. Following the removal of A. trifida, natural restoration was limited, due to the low density of the native seed bank. Above-ground new growth was dominated by weedy species, rather than by grassland species.
Sources
Wang H, Liu T, Dong H, Zhao W, Liu X, Wang R, Xu W (2022) Changes in the composition of the soil seed bank of grassland after giant ragweed (Ambrosia trifida L.) invasion. Journal of Environmental Management 317. https://doi.org/10.1016/j.jenvman.2022.115468