Urban rights-of-way as reservoirs for tall-grass prairie plants and butterflies

Published source details Leston L. & Koper N. (2016) Urban rights-of-way as reservoirs for tall-grass prairie plants and butterflies. Environmental Management, 57, 543-557.
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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
	Alter mowing regimes on greenspaces and road verges Action Link
	Manage land under power lines for butterflies and moths Action Link
	Restore or maintain species-rich grassland along road/railway verges Action Link

Stop using herbicides on pavements and road verges

A replicated, site comparison study in 2007–2008 along 52 road verges and power lines (collectively “transmission lines”) in Manitoba, Canada (Leston & Koper 2016) found that transmission lines which were not sprayed with herbicide and left unmown had more northern pearl crescent Phyciodes morpheus and pearl crescent Phyciodes tharos butterflies than frequently sprayed lines mown twice/year, but herbicide use did not affect the abundance or species richness of other butterflies. There were more crescent butterflies on unsprayed, unmown transmission lines (2.7 individuals/visit) than on frequently sprayed lines mown twice/year (0.1 individuals/visit). However, the abundance and species richness of other native butterflies was not significantly different between transmission lines which were not sprayed or mown (abundance: 11 individuals/visit; richness: 32 species), unsprayed and mown (14 individuals/visit; 21 species), infrequently sprayed and mown (11 individuals/visit; 27 species), or frequently sprayed and mown (10 individuals/visit; 21 species). See paper for species results. Fifty-two road verges and power lines (>30 m wide, >400 m long) were managed in one of four ways: 21 were neither sprayed with herbicide nor mown, but some trees were removed; 14 were sprayed frequently with herbicide and mown twice/year with cuttings left on site; 10 were sprayed infrequently with herbicide and mown once/year with cuttings left on site; seven were not sprayed and were mown once/year with cuttings baled and removed. From 15 June–15 August 2007–2008, butterflies were surveyed on one 400- or 500-m transect at each site 2–4 times/year.

(Summarised by: Andrew Bladon)
Alter mowing regimes on greenspaces and road verges

A replicated, site comparison study in 2007–2008 along 52 road verges and power lines (collectively “transmission lines”) in Manitoba, Canada (Leston & Koper 2016) found that unmown transmission lines had more northern pearl crescent Phyciodes morpheus and pearl crescent Phyciodes tharos butterflies than lines mown twice/year, but mowing regime did not affect the abundance or species richness of other butterflies. There were more crescent butterflies on unmown transmission lines (2.7 individuals/visit) than on lines mown twice/year (0.1 individuals/visit). However, the abundance and species richness of other native butterflies was not significantly different between transmission lines which were not mown (abundance: 11 individuals/visit; richness: 32 species), mown once/year and not hayed (11 individuals/visit; 27 species), mown once/year and hayed (14 individuals/visit; 21 species), or mown twice/year and sprayed with herbicide (10 individuals/visit; 21 species). See paper for species results. Fifty-two road verges and power lines (>30 m wide, >400 m long) were managed in one of four ways: 21 were neither mown nor sprayed with herbicide, but some trees were removed; 14 were mown twice/year with cuttings left on site and sprayed frequently with herbicide; 10 were mown once/year with cuttings left on site and sprayed infrequently with herbicide; seven were mown once/year with cuttings baled and removed with no spraying. From 15 June–15 August 2007–2008, butterflies were surveyed on one 400- or 500-m transect at each site 2–4 times/year.

(Summarised by: Andrew Bladon)
Manage land under power lines for butterflies and moths

A replicated, site comparison study in 2007–2008 along 52 power lines and road verges (collectively “transmission lines”) in Manitoba, Canada (Leston & Koper 2016) found that unmown transmission lines had more northern pearl crescent Phyciodes morpheus and pearl crescent Phyciodes tharos butterflies than lines mown twice/year, but mowing regime did not affect the abundance or species richness of other butterflies. There were more crescent butterflies on unmown transmission lines (2.7 individuals/visit) than on lines mown twice/year (0.1 individuals/visit). However, the abundance and species richness of other native butterflies was not significantly different between transmission lines which were not mown (abundance: 11 individuals/visit; richness: 32 species), mown once/year and not hayed (11 individuals/visit; 27 species), mown once/year and hayed (14 individuals/visit; 21 species), mown twice/year and sprayed with herbicide (10 individuals/visit; 21 species), and remnant tall-grass prairie fragments (12 individuals/visit; 20 species). See paper for species results. Fifty-two power lines and road verges (>30 m wide, >400 m long) were managed in one of four ways: 21 were neither mown nor sprayed with herbicide, but some trees were removed; 14 were mown twice/year with cuttings left on site and sprayed frequently with herbicide; 10 were mown once/year with cuttings left on site and sprayed infrequently with herbicide; seven were mown once/year with cuttings baled and removed with no spraying. Four similarly-sized remnant tall-grass prairie fragments (two urban, two rural) were managed by prescribed burning on a >3-year rotation. From 15 June–15 August 2007–2008, butterflies were surveyed on one 400- or 500-m transect at each site 2–4 times/year.

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

A replicated, site comparison study in 2007–2008 along 52 road verges and power lines (collectively “transmission lines”) in Manitoba, Canada (Leston & Koper 2016) found that managed grassland along transmission lines had a similar overall abundance and species richness of butterflies to remnant prairie fragments, but there were differences for individual species. The abundance and species richness of native butterflies along transmission lines (10–14 individuals/visit; 21–32 species) was statistically similar to remnant tall-grass prairie fragments (12 individuals/visit; 20 species). The abundance of native skippers (Hesperiidae) was higher on transmission lines cut once/year without haying (0.8 individuals/visit) than on native prairie (0.12 indiviuals/visit). The abundance of northern pearl crescent Phyciodes morpheus and pearl crescent Phyciodes tharos was higher on unmown transmission lines (2.7 individuals/visit) than on remnant prairie (0.4 individuals/visit), but lower on transmission lines mown twice/year (0.1 individuals/visit). There were also fewer fritillaries on transmission lines mown twice/year (0.1 individuals/visit) than on prairie remnants (0.5 individuals/visit). The abundance of monarch Danaus plexippus on all transmission lines (1–2 individuals/visit) was lower than on remnant prairie (5 individuals/visit). See paper for other species results. Fifty-two road verges and power lines (>30 m wide, >400 m long) were managed in one of four ways: 21 were neither mown nor sprayed with herbicide, but some trees were removed; 10 were mown once/year with cuttings left on site and sprayed infrequently with herbicide; seven were mown once/year with cuttings baled and removed with no spraying; 14 were mown twice/year with cuttings left on site and sprayed frequently with herbicide. Four similarly-sized remnant tall-grass prairie fragments (two urban, two rural) were managed by prescribed burning on a >3-year rotation. From 15 June–15 August 2007–2008, butterflies were surveyed on one 400- or 500-m transect at each site 2–4 times/year.

(Summarised by: Andrew Bladon)