Selective eradication and sowing with diverse native seed mixtures effectively controls invasion and enhances biodiversity.

Invasive alien species are one of the major threats to biodiversity and ecosystem integrity, therefore, their management is imperative. This study assessed the effectiveness of various mechanical control methods in suppressing the invasive species Solidago altissima and tested the role of sowing native seed mixtures in enhancing native diversity recovery. It was predicted that selective uprooting would be the most effective control method. Additionally, sowing high-functionally diverse seed mixtures was predicted to better suppress reinvasion than less diverse mixtures. A field experiment, containing four main plots that were subjected to non-selective mowing of all vegetation, selective cutting, selective uprooting, and no-treatment control, was conducted to test the above predictions. Each plot was subdivided into four subplots that were left untreated (control) and sown with seed mixtures containing four, eight, and 12 species from one to three functional groups (annual, herbaceous perennial, and woody perennial). Selective uprooting proved the most effective in controlling invasion, preventing reinvasion, and improving native diversity, followed by selective cutting, and non-selective mowing. Mown plots showed no significant increase over control plots in native diversity, highlighting the importance of selective removal. The most effective strategy for restoring biodiversity was uprooting S. altissima in combination with sowing with seed from a high number of functionally-diverse species. Overall, this study showed that selective eradication of an invasive species without disturbing native vegetation, combined with enhancing existing biotic resistance by sowing mixtures of functionally diverse native seeds, prevented reinvasion and improved native biodiversity to the levels comparable with undisturbed reference ecosystems.