Local and landscape effects of organic farming on butterfly species richness and abundance

Published source details Rundlöf M., Bengtsson J. & Smith H.G. (2008) Local and landscape effects of organic farming on butterfly species richness and abundance. Journal of Applied Ecology, 45, 813-820.
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This study is summarised as evidence for the following.

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A replicated, paired, site comparison study in 2004–2005 in 16 sites of arable farmland in Skåne, Sweden (Rundlöf et al 2008) found that butterfly and burnet moth species richness was higher in organic fields than in conventionally farmed fields, and in either type of field within a landscape with a high proportion of organic fields (organic landscape), whereas butterfly abundance was higher in organic fields than in conventionally farmed fields only when fields were situated within a landscape with a high proportion of conventionally farmed fields (conventional landscape). More species of butterfly were recorded in organic (average: 8) than conventionally farmed fields (average: 7). Both organic and conventionally farmed fields within organic landscapes had more butterfly species (average: 8) than the same type of field in conventional landscapes (average: 7). In conventional landscapes there were more individuals in organic fields (95) than conventionally farmed fields (46), but in organic landscapes the difference in number of individuals between organic (68) and conventionally farmed fields (56) was not statistically significant. Eight pairs of circles of land with a 1 km radius were selected (each termed a “landscape”), where one of the pair contained a high proportion of land under the Swedish agri-environment scheme for organic farming (organic landscape: 31–97% organically farmed fields) and the other had a low proportion of organic farming (conventional landscape: 2–16%). Landscapes in a pair were 2.5–7.5 km apart, with similar field sizes, crop compositions, and percentages of land in ley, pasture and arable. In each landscape, two pairs of two adjacent cereal fields were chosen. In one pair both fields matched the landscape farming practice (organic or conventional), in the other pair one field was organically farmed and one was conventionally farmed. In each field, a 250 m transect was walked five times in June–August 2004 and six times in May–August 2005 to count butterflies Rhopalocera and burnet moths Zygaenidae.

(Summarised by: Eleanor Bladon)