Weed Species Trait Selection as Shaped by Region and Crop Diversity in Organically Managed Spring Cereals

Abstract

Weeds remain a challenge in organic arable farming, as well as supply ecosystem services. The aim is to control weed densities while hosting a diverse and manageable weed community, preventing domination of few deleterious species. Therefore, we want to understand how specific species are stimulated, and which traits are selected for. This study focuses on crop diversity hypothesizing that (1) regions and (2) crop diversity function as filters for specific weed species traits. We conducted a weed monitoring in spring cereals over 2 years on organic farms in five northern European regions. Management and weed trait variables collected for the occurring species allowed an RLQ fourth-corner analysis. The weed communities were regionally specific, but trait selection was not observed, except in Latvia. Hence, the regional species pool provided different species with similar traits. Crop diversity within the management of spring cereals, such as undersowing and cereal frequency in the rotation, affected weed traits. The number of years under organic production selected no traits, although species numbers are known to increase. Hence, general weed species diversity increased, irrespective of traits. We conclude that organic management may support the agility within the weed community against selection of species and act as a buffer rather than as filter.

Traits of weed species present in maize respond to tillage and cropping systems

“…Recently, several authors used this approach to predict weed communities' responses to management changes in agricultural systems (e.g., Hawes et al, 2009;Storkey et al, 2010;Pinke and Gunton, 2014). Due to these traits, weed species can somewhat replace each other (Hofmeijer et al, 2021). Thus, weed traits successfully allow for overcoming the species focus (Fried et al, 2012;Bàrberi et al, 2018;Hofmeijer et al, 2021).…”

“…Due to these traits, weed species can somewhat replace each other (Hofmeijer et al, 2021). Thus, weed traits successfully allow for overcoming the species focus (Fried et al, 2012;Bàrberi et al, 2018;Hofmeijer et al, 2021). Today, traits are collected and publicly available in databases (e.g., LEDA 1 ; BioFlor 2 ).…”

“…The RLQ analysis considers the intercorrelation of the environment and weed traits through weed species abundance. The methods have been recently used to describe the temporal change of weed communities in wheat in France (Fried et al, 2012) and weed communities in the Baltic region (Hofmeijer et al, 2021) or to describe the effect of tillage on weed communities in wheat and soybean (Bàrberi et al, 2018).…”