Butterflies and continuous conservation reserve program filter strips: Landscape considerations

Published source details Davros N.M., Debinski D.M., Reeder K.F. & Hohman W.L. (2006) Butterflies and continuous conservation reserve program filter strips: Landscape considerations. Wildlife Society Bulletin, 34, 936-943.
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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
	Plant grass buffer strips/margins around arable or pasture fields Action Link

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

A replicated, site comparison study in 2002–2003 in 38 field margins in an arable region of Minnesota, USA (Davros et al. 2006) found that the abundance of four of eight butterfly species was higher in margins surrounded by more woodland habitat. In areas with more woodland in the surrounding landscape, the abundance of four out of eight butterfly species (orange and clouded sulphur Colias spp., monarch Danaus plexippus and regal fritillary Speyeria idalia) was higher. However, the abundance of one species (least skipper Ancyloxypha numitor) was lower in more wooded landscapes (data presented as model results). A total of 38 field margins (8–148 m wide, and all >3 years old, >350 m long, >1 km apart and with <15% tree or shrub cover) between a crop field and a water course were surveyed. None of the strips were treated with insecticide or fertilizer, and most were infrequently spot-mown or spot-sprayed to control weeds. In July–August 2002 and June–August 2003, butterflies were surveyed twice/year along one 200-m transect/margin, halfway between the water course and crop field. The habitat in a 1-km radius surrounding the midpoint of each transect was classified as “herbaceous habitat”, “crops”, “wooded”, “wetland” or “developed” areas (see paper for details).

(Summarised by: Andrew Bladon)
Plant grass buffer strips/margins around arable or pasture fields

A replicated, site comparison study in 2002–2003 in 38 buffer strips in an arable region of Minnesota, USA (Davros et al. 2006) found that wide grass buffer strips had a higher abundance of habitat-sensitive butterflies, a similar abundance of disturbance-tolerant butterflies, and a higher species richness and diversity of all butterflies, than narrow buffer strips. The abundance of habitat-sensitive butterflies, and the species richness and diversity of all butterflies, was higher in wide buffer strips than in narrower strips, but the abundance of disturbance-tolerant butterflies was similar in strips of different widths (data presented as model results). See paper for individual species results. A total of 38 buffer strips (8–148 m wide, and all >3 years old, >350 m long, >1 km apart and with <15% tree or shrub cover) between a crop field and a water course were surveyed. None of the strips were treated with insecticide or fertilizer, and most were infrequently spot-mown or spot-sprayed to control weeds. In July–August 2002 and June–August 2003, butterflies were surveyed twice/year along one 200-m transect/buffer strip, halfway between the water course and crop field. Butterfly species were classified as “disturbance-tolerant” (species commonly found in human-modified landscapes) and “habitat-sensitive” (species with specific habitat requirements often found only in natural areas).

(Summarised by: Andrew Bladon)