Mechanical control of the invasive plant Tradescantia fluminensis: effects on riparian vegetation and epigeic arthropods

Abstract

Tradescantia fluminensis is an herbaceous invasive plant that particularly affects riparian ecosystems. This study aimed to assess the impact of T. fluminensis on vegetation and epigeic arthropods, as well as to compare the effects of mechanical cutting and uprooting (hand-pulling) of the invader on these communities. Using a BACI (“Before-After-Control-Impact”) design, we compared invaded and non-invaded areas before (March) and after (May) treatments. The invader showed a negative impact on native vegetation due to its high production of aerial biomass, which forms dense mats over the understory. No significant effects of the invasion on arthropods were detected Before, but the subsequent increase in richness and abundance in non-invaded areas was lower in invaded areas After. Uprooting reduced T. fluminensis cover by 70%, promoting an early secondary succession: the plant community recovered species typical of non-invaded areas and increased the cover of many already present. Moreover, uprooting enhanced both the richness and abundance of epigeic arthropods. In contrast, mechanical cutting did not significantly reduce T. fluminensis cover nor improve the response of the vegetation or arthropod communities. This study represents the first approach to the restoration of riparian environments invaded by T. fluminensis in the Iberian Peninsula. We conclude that mechanical cutting, a commonly used control method, does not promote recovery of previously invaded areas, whereas uprooting effectively enhances ecological restoration without negatively affecting epigeic arthropods.