Avena sterilis and Lolium rigidum infestations hamper the recovery of diverse arable weed communities. (18th May 2017) - Armengot, L
Summary: Intensification of agricultural practices has severely reduced weed diversity in arable fields, which affects the delivery of ecosystem services. However, in parallel, some species have benefited from intensive farming and have vastly increased their abundance, as is the case for Lolium rigidum and Avena sterilis in cereal fields. These highly competitive species severely reduce yields but can also compete with other weed species, and, when less intensive practices are applied, they might limit the recovery of weed diversity and the success of arable species reintroductions. A gradient of infestation was established in a winter wheat field in Catalonia (north‐eastern Spain) by sowing seeds of both species at three different densities to test their effects on the abundance, diversity and composition of the natural weed community. The emergence of seeds and the survival and biomass of transplanted seedlings of two rare species, Agrostemma githago and Vaccaria hispanica, were also evaluated. Avena sterilis and L. rigidum infestations reduced the diversity, abundance and biomass and changed the composition of the natural weed community, even at low infestation densities. Moreover, infestations of both species affected the overall performance of A. githago and V. hispanica . This study reveals that A. sterilis and L. rigidum are highly competitive and that their infestations might hamper the recovery of diverse weed communities. Their densities should be considered when selecting suitable sites for promoting diversity and reintroducing rare species.