Vegetation cover at the water surface best explains seed retention in open channels

Hydrochorous dispersal through agricultural channels plays a role in structuring plant communities across landscapes. To date, research on seed retention vegetated areas has mainly focused vegetation types with simple architecture (often cylinders), which consequently do not represent real features. Here, we test the hypothesis that cover estimated at water surface best explains floating open channels. We therefore proposed an experiment to measure controlled environment large range of hydraulic conditions and types. used three artificial plants contrasting morphotypes, seeds Rumex crispus. Vegetation metrics were calculated basis 3D models. also tested additivity as function length area crossed by seeds. developed semi-empirical formula for predicting retention. The main results show (i) rate reacts differently changes density according species, (ii) free surface, potentially contact seeds, is generic predictor whatever nature cover, (iii) 95% was reached ratios cover. could be stakeholders (farmers ecologists) estimate amount needed channel limit or enhance dispersal.