Conservation value of roadside prairie restoration to butterfly communities

Published source details Ries L., Debinski D.M. & Wieland M.L. (2001) Conservation value of roadside prairie restoration to butterfly communities. Conservation Biology, 15, 401-411.
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This study is summarised as evidence for the following.

	Action	Category
	Stop using herbicides on pavements and road verges Action Link
	Restore or maintain species-rich grassland along road/railway verges Action Link

Stop using herbicides on pavements and road verges

A replicated, paired, site comparison study in 1998 in 12 road verges in Iowa, USA (Ries et al. 2001) found that restored roadside prairies where herbicide application was restricted had a higher abundance and species richness of habitat-sensitive butterflies than verges dominated by non-native weeds or grasses with no herbicide restrictions. On restored roadside prairies with herbicide restrictions, both the abundance (2.3 individuals/plot) and species richness (1.6 species/plot) of habitat-sensitive butterflies was higher than on roadsides with no herbicide restrictions and dominated by weeds (abundance: 1.4 individuals/plot; richness: 0.9 species/plot) or grasses (0.5 individuals/plot; 0.7 species/plot), and not significantly different from remnant prairies (1.6 individuals/plot; 1.7 species/plot). In addition, mortality risk was lower on prairie or weedy road verges than on non-native grass verges (data presented as model results). On eight well-established, restored prairie road verges (>0.5 km long) and four native (never ploughed) prairie verges dominated by native prairie vegetation, the use of herbicides was restricted. Roadside vegetation (>6 m wide) within 1.6 km of the 12 prairies, but with no restrictions on herbicide use, was classified as “weedy” (>20% non-native legumes) or “grassy” (dominated by non-native grasses). From June–August 1998, butterflies were surveyed nine times in 1–3 plots/habitat (restored prairie, native prairie, weedy, grassy) at each of 12 sites. Plots were 50 × 5 m, >50 m apart and >500 m from a different verge habitat. In addition, three plots in each of four native prairie remnants (2–16 ha) were surveyed. Roadkill butterflies were surveyed six times along both road edges next to each plot.

(Summarised by: Andrew Bladon)
Restore or maintain species-rich grassland along road/railway verges

A replicated, paired, site comparison study in 1998 in 12 road verges in Iowa, USA (Ries et al. 2001) found that restored roadside prairies where herbicide application was restricted had a higher abundance and species richness of habitat-sensitive butterflies than verges dominated by non-native weeds or grasses with no herbicide restrictions. On restored roadside prairies, both the abundance (2.3 individuals/plot) and species richness (1.6 species/plot) of habitat-sensitive butterflies was higher than on roadsides dominated by non-native weeds (abundance: 1.4 individuals/plot; richness: 0.9 species/plot) or grasses (0.5 individuals/plot; 0.7 species/plot), and not significantly different from remnant prairies (1.6 individuals/plot; 1.7 species/plot). In addition, mortality risk was lower on prairie or weedy road verges than on non-native grass verges (data presented as model results). On eight well-established, restored prairie road verges (>0.5 km long) and four native (never ploughed) prairie verges dominated by native prairie vegetation, the use of herbicides was restricted. Roadside vegetation (>6 m wide) within 1.6 km of the 12 prairies was classified as “weedy” (>20% non-native legumes) or “grassy” (dominated by non-native grasses). From June–August 1998, butterflies were surveyed nine times in 1–3 plots/habitat (restored prairie, native prairie, weedy, grassy) at each of 12 sites. Plots were 50 × 5 m, >50 m apart and >500 m from a different verge habitat. In addition, three plots in each of four native prairie remnants (2–16 ha) were surveyed. Roadkill butterflies were surveyed six times along both road edges next to each plot.

(Summarised by: Andrew Bladon)