Reintroduction strategies for rare arable weeds in agricultural practice and their influence on yield

Abstract

Agricultural intensification and changing landscape structure led to decreasing numbers of arable flora and fauna during the last decades. To counteract these declines, arable plant diversity needs to be restored. It is important to promote regional plant communities including endangered species to ensure adaption to agricultural landscapes. Therefore, this study examines the development of arable plant diversity, crop yield and the reintroduction success of rare arable plants (RAPs) under different practical farming strategies in cereals from 2019 to 2021 in southwestern Germany. Farming strategies varied regarding weed control intensity (none, mechanical, herbicide with and without efficiency gap), fertilisation (mineral and none) and row spacing (12.5 cm and 20 cm). Additionally, two different seed mixtures containing RAP and common species were used for reintroduction: one commercially available and another self‐composed. Reintroduction success was quite high with more than 80% establishment rate. Species numbers doubled in all treatments over time, except the one with herbicide application, with on average 8–10 species emerging from the soil seed bank. Reintroduction of RAP increased arable plant species richness further up to 37 species. The site‐adapted mixture showed in the end a site‐typical weed community. Yield was significantly lower in treatments with reintroduction via sown mixtures and no weed control, losing on average 65% yield. The reintroduction of RAP was successful and accompanied by an increasing floral diversity, however, with a simultaneous yield loss. Financial incentives or subsidies are therefore still necessary to compensate yield loss for reintroduction and conservation efforts.