Diversifying crop rotations with temporary grasslands - Université de ...
Diversifying crop rotations with temporary grasslands - Université de ...
Diversifying crop rotations with temporary grasslands - Université de ...
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Declines in weed diversity may have severe impacts on many other organisms (various types<br />
of animals and micro-organisms) that are using weeds either as hosts or food resources<br />
(Gerowitt et al., 2003; Marshall et al., 2003; Holland et al., 2006; Storkey, 2006). Weeds may<br />
therefore be well suited as indicator organisms for farmland biodiversity in general (Albrecht,<br />
2003). A large panel of different organisms may <strong>de</strong>pend on weeds including herbivores,<br />
pollinators, seed eaters, and <strong>de</strong>composers as well as organisms at higher trophic levels of<br />
many different taxonomic groups, e.g. arthropods (Norris and Kogan, 2005). Birds attracted<br />
the most attention. During the last <strong>de</strong>ca<strong>de</strong>s, farmland birds showed dramatic populations<br />
<strong>de</strong>creases in many European countries (Krebs et al., 1999; Bretagnolle, 2004; European Bird<br />
Census Council EBCC, 2008), which was much stronger than for any other group of birds<br />
(Fig. 1). Of the 195 bird species <strong>with</strong> an unfavourable conservation status in Europe, 116 are<br />
farmland birds (European Bird Census Council EBCC, 2008).<br />
Fig. 1: Population trends of common bird species in Europe.<br />
The graph (taken from the European Bird Census Council EBCC, 2008) shows an in<strong>de</strong>x of the average breeding<br />
population <strong>de</strong>nsities of 36 common farmland bird species (red line), which <strong>de</strong>creased by about 50% from 1980 to<br />
2006, while all common birds (black line) and forest birds (blue line) <strong>de</strong>clined by only 10%. Shown are weighted<br />
geometric means from 21 European countries (Austria, Belgium, Bulgaria, Czech Republic, Denmark, Estonia,<br />
Finland, France, Germany, Hungary, Ireland, Italy, Latvia, Netherlands, Norway, Poland, Portugal, Spain,<br />
Swe<strong>de</strong>n, Switzerland, United Kingdom) that were compiled by the Pan-European Common Bird Monitoring<br />
Scheme (PECBMS), a common initiative of the EBCC, the Royal Society for the Protection of the Birds (RSBP),<br />
BirdLife International, and Statistics Netherlands.<br />
These strong <strong>de</strong>clines of farmland birds were probably caused by habitat <strong>de</strong>struction and food<br />
shortages linked to agricultural intensification (Fuller et al., 1995; Siriwar<strong>de</strong>na et al., 2000;<br />
7