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RESEARCH PRODUCT

The spatial and temporal distribution of carabid and weed seed predation in winter wheat: a comparison between conventional and conservation agriculture systems

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description

Carabids can be key players in weed seed predation within arable crops under temperate climate. Field management options, because they affect carabid communities, may represent potential levers to increase weed seed predation levels within fields. Among these options, Conservation Agriculture is often presented as a promising management option for carabids but its effect on weed seed predation levels is less clear. In this study, carabids and weed seed predation were monitored using a grid sampling from April till September 2011 in two adjacent winter-wheat fields in North-eastern France, one conducted as no-till with cover crop for 5 years (conservation agriculture) and the other as conventional tillage. A grid sampling of 66 plots (one plot = 2 pitfall traps and 2 predation cards under exclosure cages) was used to assess the activity density of carabid trophic guilds and seed predation rate over the two fields. Our results indicate that the relative importance of the carabid trophic guilds and seed predation were comparable in the two systems during the wheat growing season but that granivorous species became scarce and predation rates dropped significantly in the no-till system after harvest. An analysis of the correlations between the spatial distribution of predation and the different carabid trophic guilds using the MAPCOMP software gave us some insight as to the processes underlying seed predation in the two systems.