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

field margin strips (compare Articles 7 and 8) and (ii) positively related to vegetation cover in
perennial forage crops, explaining 3 % - 27 % of the variability (see Table 3 and references in
Article 8). Due to these two reasons, the total seed predation cumulated over a whole year is
probably more important in perennial crops compared to annual crops, which is in accordance
with experimental results recently obtained in Iowa, USA (Westerman et al., 2005;
Heggenstaller et al., 2006).
The results also suggested that weed seed predation rates differ strongly between weed
species. Such differences between weed species were already detected in previous studies
(White et al., 2007). Interestingly, a comparison of the predation rates of seven common weed
species between the studies in 2007 (Article 6) and 2008 (Articles 7 and 8) showed that the
species preference order is quite stable across situations (see Fig. 22).
Predation rate 2008 [%]
60
40
20
0
SINAR
GALAP
ANGAR
Fig. 22: Comparison of weed seed predation rates of the 2007 and 2008 experiments (cf. Article 6 and 8).
Shown are mean ±SE predation rates for 7 weed species and plastic globules for control (see Table 7 or Annexe 3
for species codes). N=105 for the 2007 trial (Article 6), N=28 for the 2008 trial (Article 8, seven treatments
confounded). The bold line shows the regression y=0.684x, R²=0.535. Mean predation rates of all species except
Sinapis arvensis tended thus to be higher in the 2007 experiment (means below the broken x=y line).
166
y=x
CHEAL
STEME
0
Plastic
20 40 60 80
Predation rate 2007 [%]
VIOAR
ALOMY