The role of organic farms as refugia for biodiversity
Organic farming generally is acknowledged for the positive effects on biodiversity and other landscape services. However, the intensity of farming has changed significantly through the last decade as ranks of traditional holistic organic farmers has been augmented by much more economically driven new organic farmers.
At the same time there have also been steady improvements in farming methodology and crop types resulting in efficiency in organic farming which can often rival its conventional counterparts. Therefore, large variations occur between organic farms.
The present project aims at increasing society's and consumers' knowledge about the impact of organic farming on nature by investigating the role of different types of organic farms as refugia for biodiversity.
This is addressed within the work packages 2-7 by:
- Investigating the structure, diversity and intensity of organic farming, and its role for multifunctionality in Denmark. (WP 2)
- Investigating weed-insect food chains for two crops within intensively and extensively cultivated organic fields in order to compare with existing data for conventional farms. This will give information about the amount of non-crop food available for birds and small mammals feeding in the fields and about whether organic fields sustain more food chains than conventional fields. (WP 3)
- Investigating the plant produced food resources in terms of flowering period and weed seeds available for insects, birds and small mammals in hedges and field margins at organic and conventional farms. The data will show whether the documented differences in the flora between hedge vegetation at organic and conventional farms are mirrored in the resource availability. (WP 4).
- Investigating the role of organic farms as genetic sources for species in the arable land by analysing the genetic diversity and population structure of “wild” species in the arable landscape. This will be performed assuming firstly that the upland habitats in hedgerows and fields/grassland of organic farms function both as islands and corridors connecting the islands for flora and fauna, and secondly, that the use of pesticides in conventional agriculture causes frequent local extinction and re-colonisation events of weed and invertebrates. Such events will indirectly affect smaller mammals and farmland birds due to local extinction of food-items.
The impact on genetic structure may vary according to the species in question depending amongst others on the species' dispersal ability. This will be addressed by focussing on the three species, grey partridge (Perdix perdix), ground beetle (Pterostichus spp.) and field vole (Microtus agrestis) representing three different taxa with different dispersal abilities (WP5 and 6).
- Investigating the impact that organic farms have on the wildlife content of the landscape by creating a set of landscape configurations using the information from WP2 on the agricultural extensiveness and distribution of organic farms and from WP 2, 3 and 4 on the species ecology, genetic patterns and species diversity.
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Modeling tools will be used to synthesize this information and to create a set of indices for describing the ability of a landscape configuration of organic farms to support a range of wildlife. The resulting landscape wildlife index (LWI) will have the potential to be used by interest groups to determine which scenarios result in the optimum wildlife potential from their particular viewpoint (WP7).
The LWI index will provide an effective way of measuring"nature quality" from a faunal perspective and will provide the ability to make a direct estimate of the contribution of organic farms to the overall value of the landscape for a range of agricultural species. In this way an organic farmer can evaluate the impact that he could have as an individual on biodiversity via the choices he might make regarding the intensity with which he farms.
Project title
The role of organic farms as refugia for biodiversity (REFUGIA)
Project leader
Liselotte Wesley Andersen, Senior scientist, National Environmental Research Institute (NERI), Department of Wildlife Ecology and Biodiversity, Grenåvej 12, 8410 Rønde, Denmark. Phone: (+45) 8920 1713, Fax: (+45) 8920 1514. E-mail: lwa@dmu.dk
Project participants
Chris Topping, Beate Strandberg, Marianne Bruus, Christian Damgaard (National Environmental Research Institute), Thomas Secher Jensen, Tine Sussi Hansen (Natural History Museum), Tommy Dalgaard, Peder Klith Bøcher, Mette Balslev Greve (Faculty of Agricultural Sciences, University of Aarhus).
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