Use prescribed fire to maintain or restore disturbance in grasslands or other open habitats

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Nine studies evaluated the effects on butterflies and moths of using prescribed fire to maintain or restore disturbance in grasslands or other open habitats. Five studies were in the USA, three were in the UK and one was a review across Europe.

COMMUNITY RESPONSE (2 STUDIES)

  • Community composition (1 study): One replicated, site comparison study in the USA found that pastures managed by patch-burning had a similar butterfly community to rotationally or continuously grazed pastures.
  • Richness/diversity (2 studies): One replicated, randomized, controlled, before-and-after study in the USA found that grass field margins managed by burning had a similar species richness of butterflies to unburned field margins. One replicated, site comparison study in the USA reported that pastures managed by patch-burning had a lower species richness of butterflies than rotationally grazed pastures, a similar richness to rotationally grazed and mown pastures, and a higher species richness than continuously grazed pastures.

POPULATION RESPONSE (9 STUDIES)

  • Abundance (9 studies): Three of six studies (including two controlled studies, two before-and-after studies, and one three comparison studies) in the UK and the USA found that the abundance of heath fritillary adults, marsh fritillary caterpillar webs and Fender’s blue caterpillars and eggs was higher (sometimes after initial reductions in abundance) on heathland, fen meadows and prairies two or more years after management by burning than before burning, or compared to unburned or grazed land, although the total population of Fender’s blue declined in adjacent burned and unburned areas. Two studies found that the abundance of rosy marsh moth caterpillars and regal fritillary adults was lower on a bog and prairies managed by burning than on unburned land, for at least one and five years after burning. The sixth study found that grass field margins managed by burning had a similar abundance of butterflies to unburned field margins. Two replicated, site comparison studies in the USA found that two prairie specialists (regal fritillary and arogos skipper) and three out of nine butterfly species were less abundant in prairies or pastures managed by burning than in prairies managed by haying or grazed pastures. These studies also found that the abundance of generalist and migrant species, and of purplish copper, was higher in burned prairies or pastures than hayed prairies or grazed pastures. One review across Europe reported that occasional burning on grassland benefitted 10 out of 67 butterfly species of conservation concern.

BEHAVIOUR (1 STUDY)

  • Use (1 study): One replicated, site comparison study in the UK found that a similar proportion of fen meadows were occupied by marsh fritillary caterpillars whether they were managed by burning, grazing or were unmanaged.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A before-and-after study in 1980–1989 on a heathland on Exmoor, UK (Warren 1991) reported that prescribed burning increased the number of heath fritillary Mellicta athalia. Results were not tested for statistical significance. Seven years after burning, over 5,500 adult heath fritillary were recorded at the site, compared to 280 adults two years before burning. However, in the summer after burning, no heath fritillaries were seen, and only 17 were recorded the following year. The author noted that these adults may have recolonized from a neighbouring site 500 m away. In March 1982, most of a 9-ha heathland was burned. In 1980, and from 1982–1989, butterflies were surveyed annually on timed counts along a zig-zag route covering the known flight area.

    Study and other actions tested
  2. A replicated, site comparison study in 1992–1993 in 42 tall-grass prairies in Missouri, USA (Swengel 1996) found that two prairie specialist butterflies were less abundant, but generalist and migrant species were more abundant, in burned than in hayed prairies. At sites managed by burning, the abundance of two prairie specialists (regal fritillary Speyeria idalia and arogos skipper Atrytone arogos; 2–21 individuals/hour) was lower than at sites managed by haying (68–81 individuals/hour). However, generalist and migrant species were more abundant at burned sites (18–24 individuals/hour) than hayed sites (6–19 individuals/hour). See paper for some individual species results. Of 42 sites (6–571 ha), some were managed by cool-season burning covering 5–99% of the site, and the rest by summer haying on a 1–3 year rotation with occasional cattle grazing (number of sites in each management not given). In June 1992–1993, butterflies were surveyed at least once/year at most sites, either along a transect (35 sites) or from a single point (7 sites, recording only regal fritillary). Sixteen species observed >49 times and at >5 sites were included, and divided into “prairie specialists” (only found on prairies), “grassland species” (found in prairies and other grasslands), “generalists” (found in grasslands and other habitats) and “migrants” (only present in the study area during the growing season).

    Study and other actions tested
  3. A replicated, site comparison study in 1993 in 34 fen meadows in Glamorgan, UK (Lewis & Hurford 1997) found that managing grassland by burning did not affect site use by marsh fritillary Eurodryas aurinia compared to grazed or unmanaged grassland. There was no significant difference in the proportion of burned (5/8 sites), cattle-grazed (3/9), horse-grazed (2/6), sheep-grazed (0/2), mown (0/1) and unmanaged (4/8) sites that had >20 caterpillar webs recorded. However, the three largest populations (>200 caterpillar webs) were on sites burned in early spring. Caterpillar webs were present on 28/34 sites where adults had been recorded in May/June. In 1993, eight grasslands were burned, nine were cattle-grazed, six were horse-grazed, two were sheep-grazed, one was mown and eight were unmanaged. Sites were separated by >1 km of unoccupied grassland, or >0.5 km of unsuitable habitat. From late August–mid-October 1993, caterpillar webs were surveyed on 34 fen grasslands. On sites <2 ha, all devil’s bit scabious Succisa pratensis were searched in 2-m-wide parallel strips until the whole area had been searched. On larger sites, 2-m-wide strips at 10-m intervals were searched, and areas around caterpillar webs were then searched comprehensively.

    Study and other actions tested
  4. A site comparison study in 1988–2003 in a raised bog in Ceredigion, UK (Fowles et al. 2004) reported that a burned bog had fewer rosy marsh moth Coenophila subrosea caterpillars than an unburned bog. Results were not tested for statistical significance. For 2–5 years after burning, caterpillars were scarce in the burned area (0–3 individuals/year) compared to the unburned area (6–24 individuals/year). From 6–9 years after burning, numbers were similar in burned (5–13 individuals/year) and unburned (6–15 individuals/year) areas. From 10–14 years after burning, the burned area had 6–24 individuals/year compared to 2–17 individuals/year on the unburned area. From 16–17 years after burning, the burned area had 16–38 individuals/year compared to 33–50 individuals/year on the unburned area. From 1968, fire frequency was reduced on a raised bog, and the last burn occurred in 1974. In February 1986, two-thirds of the bog was accidentally burned. In late May 1988–2003, caterpillars were counted once/year, at night, in seven 15 × 1 m plots in the burned area and seven in the unburned area.

    Study and other actions tested
  5. A replicated, site comparison study in 2005 in 87 remnant prairies in Kansas, USA (Powell et al. 2007) found that recently burned prairies had fewer regal fritillaries Speyeria idalia than prairies which had not been burned for at least a year. There were fewer regal fritillaries on prairies which had been burned since the last growing season (0.9 individuals/100 m) than on prairies which were unburned in that time (3.2 individuals/100 m). However, the presence of fritillaries at a site was similar between burned (16/21 sites) and unburned (54/66 sites) prairies. Eighty-seven tallgrass prairie remnants (0.9–53.9 ha) were managed by either burning (usually in April), cutting once/year in July, or grazing. In June 2005, signs of recent fire were used to classify sites at recently burned (since autumn 2004) or unburned in that time. In June 2005, regal fritillaries were surveyed along transects (130–1,300 m long), >30 m from the edge of the prairie.

    Study and other actions tested
  6. A replicated, randomized, controlled, before-and-after study in 2007–2009 on a mixed farm in Mississippi, USA (Dollar et al. 2013) found that burning grass field margins did not increase the abundance or species richness of either disturbance-tolerant or grassland butterflies. The abundance and species richness of 18 disturbance-tolerant butterfly species was similar on burned (abundance: 4–11 individuals; richness: 6–7 species) and undisturbed (abundance: 4–14 individuals; richness: 6–8 species) grass field margins. The abundance and species richness of 14 grassland butterfly species also remained similar in burned (abundance: 0.3–1.3 individuals; richness: 1–3 species) and undisturbed (abundance: 0.5–1.3; richness: 1–3 species) margins. See paper for details of individual species. In spring 2004, grass margins were sown with a seed mix of common prairie species. Ten fields (containing 26 margins) were randomly assigned to one of two treatments: burning and no disturbance. Within each burning field, one margin was burned in spring 2008 and a different margin was burned in spring 2009. From June–August 2007–2009, butterflies were surveyed six times/year along three 50-m transects in the centre of each margin.

    Study and other actions tested
  7. A review in 2015 of 126 studies in Europe (Bubová et al. 2015) reported that occasional burning on grassland benefitted 10 out of 67 butterfly species of conservation concern. Results were not tested for statistical significance. The review reported that seven studies found that occasional burning benefitted 10 butterfly species (large heath Coenonympha tullia, woodland grayling Hipparchia fagi, rock grayling Hipparchia hermione, tree grayling Hipparchia statilinus, Iolas blue Iolana iolas, large blue Phengaris arion, scarce large blue Phengaris teleius, zephyr blue Plebejus pylaon, Piedmont anomalous blue Polyommatus humedasae, Kolev’s anomalous blue Polyommatus orphicus). The authors suggested that negative short-term impacts of burning can be reduced by leaving small areas of land unburned, and by burning in winter or early spring (data not presented). Meadows were burned in different patterns and at different times of year. The review focussed on 67 butterfly species of conservation concern. The available information was biased towards studies in Northern and Western Europe.

    Study and other actions tested
  8. A replicated, site comparison study in 2015–2016 in two grassland reserves in North Dakota, USA (Bendel et al 2018) found that burning patches of pasture did not affect butterfly community composition, but did affect the species richness and abundance of individual species, compared to management by rotational grazing, rotational grazing with mowing, and season-long grazing. Patch-burning did not affect butterfly community composition compared to other management (data presented as model results). One out of nine species (purplish copper Lycaena helloides) was more abundant in patch-burned pastures, while three species (meadow fritillary Boloria bellona, regal fritillary Speyeria idalia and small pearl-bordered fritillary Boloria selene) were less abundant in patch-burned pastures than other management, and five species had a similar abundance between management types (see paper for details). Twenty-six butterfly species were recorded in patch-burned grazed pastures, compared to 30 species in rotationally grazed pastures, 25 species in rotationally grazed pastures with mowing and 22 species in season-long grazed pastures (statistical significance not assessed). Eight pastures (54–484 ha) managed under one of four management practices (patch-burn grazing, rotational grazing, rotational grazing with lowland mowing, season-long grazing) were selected. One-third of each patch-burn pasture was burned in the dormant season, but prior to April 2015 these sites were rotationally grazed. All other sites had the same management for at least a decade. Rotational pastures were sub-divided into four paddocks, each grazed twice/season. In mown pastures, sedge-dominated patches were cut once/summer. On season-long pastures cattle were free to select grazing areas. Pastures were stocked with cattle (0.5–0.75 cow-calf pairs/ha) from May–October. From June–August 2015 and 2016, butterflies were surveyed three times/year along twelve 100-m transects/pasture.

    Study and other actions tested
  9. A replicated, randomized, paired, controlled study in 2011–2014 in four upland prairies in Oregon, USA (Warchola et al. 2018) found that prescribed burning in autumn initially reduced the amount of Fender’s blue caterpillar damage, but then the number of eggs and amount of caterpillar damage in burned areas was higher than in unburned areas for two years after burning, although the overall population decreased in both areas. In the first spring after burning, fewer Kincaid’s lupine Lupinus oreganus and spur lupine Lupinus arbustus plants had damage from Fender’s blue caterpillars, per egg found the previous June, in burned plots (0.1 leaves/egg) than in unburned plots (0.3 leaves/egg). However, the following year, there were more damaged leaves in burned (1.2 leaves/egg) than unburned (0.7 leaves/egg) plots, but there was no difference by the third year after burning (burned: 0.3 leaves/egg; unburned: 0.3 leaves/egg). For two years after burning, there were also more eggs in June, per caterpillar found in April, in burned plots (67–68 eggs/caterpillar) than in unburned plots (48–49 eggs/caterpillar), but by the third year after burning the number was similar in burned (26 eggs/caterpillar) and unburned (25 eggs/caterpillar) plots. However, the population declined by 78% in the burned areas and 83% in the unburned areas (statistical significance not assessed). In October 2011, half of each of four prairies was burned (0.07–0.21 ha burned), and the remaining area was not burned. In June 2011–2014, Fender’s blue eggs were surveyed in twenty 1-m2 plots/patch (160 plots total) with ≥30% cover of lupine. In April 2012–2014, the number of caterpillars was estimated by counting the number of lupine leaves with characteristic Fender’s blue feeding damage.

    Study and other actions tested
Please cite as:

Bladon A.J., Smith R.K. & Sutherland W.J. (2022) Butterfly and Moth Conservation: Global Evidence for the Effects of Interventions for butterflies and moths. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

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Butterfly and Moth Conservation

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Butterfly and Moth Conservation
Butterfly and Moth Conservation

Butterfly and Moth Conservation - Published 2022

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