Diversifying crop rotations with temporary grasslands - Université de ...

Fig. 3: Published estimations of superficial weed seed densities in arable soils during the 20th century.
The figure is reproduced with permission from a literature review by Robinson & Sutherland (2002). Points
represent densities of dicotyledonous seed in the top 1 cm of soil in arable fields in Britain (filled symbols) and
Denmark (open symbols). Studies were included only if they sampled the entire seed bank between September
and November and if the fields had been part of a cereal-based rotation for at least 5 years; results from adjacent
fields and years have been averaged.
While farmland biodiversity declines are best documented for the group of birds, many other
animal groups including amphibians, reptiles, mammals and various invertebrates also showed
reduced abundances and diversities which may often equally be linked to the reduced diversity
of wild plants (see review by Robinson and Sutherland, 2002).
A.II.4 Summary
Seed density m -2
The section above has shown that (i) weed populations must be controlled to enable a high
crop production, but that (ii) the concentration on chemical weed control is not sustainable due
to widespread environmental pollution, possible impacts on human health, high economic
costs and the risk of selecting herbicide resistances, and that (iii) weed abundance and
diversity showed strong reductions due to modern farming practices, which had also
detrimental effects on other elements of biodiversity and ecosystem functioning. This triple
‘weed trade-off’ must be solved to improve the sustainability of agriculture. However, there is
probably no single solution to this complex problem.
9