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

and 2008 within the framework of the collaborative research project ‘Gestion durable des
ressources naturelles en plaine céréalière: le rôle central des surfaces pérennes dans les
agro-écosystèmes céréaliers’ involving different INRA and CNRS research teams that were
part of the ECOGER project (see the ‘Context and funding’ section for details). Weed surveys
were mainly realized by members of the ‘weed biology and management’ research group
(UMR BGA, INRA Dijon) and of the ‘Agronomy’ research group (UMR ‘Agronomie’,
AgroParisTech).
The taxonomy of plant species followed Tela-Botanica (http://www.tela-
botanica.org/page:eflore). Weed species composition in each field was based on species
frequencies on the field scale which were calculated by presence-absence data from 30-32
plots surveyed per field (see Methods of Articles 1 and 2 for further details on the weed
surveys). Crop volunteers were excluded from all analysis, even though they are often also
considered as weeds (the term ‘weed’ is defined in Annexe 2). Crop volunteers are often
closely associated to the preceding crops and may thus obviously increase the differences in
the weed species composition.
While the first analysis needed only information on the current crops, analysis 2 was based on
the crop sequence history of each field which was taken from a databank of the common
ECOGER-research project containing the land-use data of the whole study area. This huge
dataset was established by annually recording the crop species grown on each of the 18000
fields (with varying geometry) since 1995 and mapping it into a GIS databank (see Lazrak et
al., 2009 for details).
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