At what spatial scale do high-quality habitats enhance the diversity of forbs and pollinators in intensively farmed landscapes?
Article first published online: 9 OCT 2007
© 2007 The Authors. Journal compilation © 2007 British Ecological Society
Journal of Applied Ecology
Volume 45, Issue 3, pages 753–762, June 2008
How to Cite
Kohler, F., Verhulst, J., Van Klink, R. and Kleijn, D. (2008), At what spatial scale do high-quality habitats enhance the diversity of forbs and pollinators in intensively farmed landscapes?. Journal of Applied Ecology, 45: 753–762. doi: 10.1111/j.1365-2664.2007.01394.x
- Issue published online: 9 OCT 2007
- Article first published online: 9 OCT 2007
- Received 30 January 2007; accepted 20 July 2007Handling Editor: Davy McCracken
- ditch banks;
- hover flies;
- species density
- 1Over the last decades, biodiversity in agricultural landscapes has declined drastically. Initiatives to enhance biodiversity, such as agri-environment schemes, often have little effect, especially in intensively farmed landscapes. The effectiveness of conservation management may be improved by scheme implementation near high-quality habitats that can act as a source of species. We evaluated up to what distance high-quality habitats (nature reserves and artificially created flower-rich patches) affect the diversity of forbs and pollinators in intensively farmed landscapes of the Netherlands.
- 2We surveyed forbs, inflorescences, bees and hover flies and estimated pollination services in transects along ditch banks extending 300 m from four nature reserves forming small islands in landscapes dominated by agriculture.
- 3In a separate experiment, we surveyed inflorescences, bees and hover flies in 1500 m long transects on farmland adjacent to five newly introduced flower-rich patches and in five control transects.
- 4Species density of forbs declined over the first 75 m and species density and abundance of hover flies declined over the first 125 m beyond the nature reserves. Beyond these distances, no further declines were observed. The effects of flower-rich patches were spatially limited. The species density and abundance of bees and hover flies were significantly enhanced in the flower-rich patch, but only the abundance of hover flies was enhanced up to 50 m beyond the patch.
- 5Synthesis and applications. In intensively farmed areas, remnant high-quality habitats sustain more abundant and diverse pollinator and forb communities than the surrounding countryside. They do enhance biodiversity on nearby farmland but increases are spatially restricted (< 150 m) and relatively small. These habitats may therefore function only as dispersal sources for ecological restoration sites or agricultural fields under extensification schemes that are located in close proximity. Habitat restoration in intensively used farmland should therefore be implemented preferentially in the immediate vicinity of high-quality habitats. In the short term, newly created flower-rich habitats are no alternative to pre-existing seminatural habitats for the promotion of pollinators on nearby farmland.