Assessing the effect of the time since transition to organic farming on plants and butterflies

Published source details Jonason D., Andersson G.K., Öckinger E., Rundlöf M., Smith H.G. & Bengtsson J. (2011) Assessing the effect of the time since transition to organic farming on plants and butterflies. Journal of Applied Ecology, 48, 543-550.
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This study is summarised as evidence for the following.

	Action	Category
	Increase or maintain the proportion of natural or semi‐natural habitat in the farmed landscape Action Link
	Convert to organic farming Action Link

Increase or maintain the proportion of natural or semi‐natural habitat in the farmed landscape

A replicated, site comparison study in 2009 in 60 arable farms in Uppland and Scania, Sweden (Jonason et al. 2011) found that butterfly and burnet moth species richness, but not abundance, was higher in farms surrounded by a greater proportion of forest-dominated land than those surrounded by a greater proportion of arable farmland. Farms within a 1 km radius with a higher proportion of forest-dominated land and a lower proportion of arable land had higher butterfly species richness compared to those with a higher proportion of arable land and a lower proportion of forest-dominated land (data presented as statistical results). However, the relative proportions of forest-dominated and arable land resulted in no difference in butterfly abundance. In June–August 2009, butterfly surveys were carried out in 40 organic and 20 conventionally-managed farms. On each farm, three 250 m transects were completed 5–6 times - one in an uncultivated margin of a cereal field, and two within the field at 50 m and 200 m from the margin transect. Butterflies Rhopalocera and burnet moths Zygaenidae were identified to species. The proportion of arable land within a radius of 1 km from each farm was calculated using remote sensing imagery. The proportion of arable land ranged from 20–80%.

(Summarised by: Eleanor Bladon)
Convert to organic farming

A replicated, site comparison study in 2009 in 60 arable farms in Uppland and Scania, Sweden (Jonason et al 2011, same experimental set up as Jonason et al 2012) found that butterfly abundance and species richness was higher on organic than conventionally-managed farms, and butterfly abundance, but not richness, increased with the time since a farm had been converted to organic farming. Butterfly abundance was 60% higher on organic (average: 68 individuals) than conventional farms (42 individuals). Species richness was 23% higher on organic (average: 10 species) than conventional farms (8 species). Butterfly abundance increased steadily with years since land was converted from conventionally-managed to organic farming, but time since conversion to organic did not affect species richness (data presented as statistical results). In June–August 2009, butterfly surveys were carried out in 40 organic and 20 conventionally-managed farms. Organic farms varied in time since conversion from conventional management (1–25 years). On each farm, three 250 m transects were completed 5–6 times - one in an uncultivated margin of a cereal field, and two within the field at 50 m and 200 m from the margin transect. Butterflies and burnet moths Zygaenidae were identified to species.

(Summarised by: Eleanor Bladon)