Change season/timing of prescribed burning
Overall effectiveness category Awaiting assessment
Number of studies: 2
Background information and definitions
Open habitats, such as grassland, heathland, peatland and fynbos, require disturbance processes to prevent them undergoing succession to scrub or woodland. One option for preventing succession and opening up areas of habitat is to use prescribed burning. Although destructive in the short-term, with the likely loss of butterflies and moths through direct mortality or reductions in food availability (Glaves et al. 2013), burning may have long-term benefits by creating a more favourable, open habitat (Bubová et al. 2015), with increases in structural diversity (Glaves et al. 2013) or flower density (Vogel et al. 2010). However, the impact of fires can vary depending on their exact characteristics, such as the frequency, temperature, ground surface intensity, time and size of burning compared to the surrounding unburned areas (Swengel 2001, Tucker 2003, New et al. 2010) and caution should be taken before instigating fire in place of alternative management options such as grazing or cutting.
For studies on the impact of single prescribed burns, see “Use prescribed fire to maintain or restore disturbance in grasslands or other open habitats”. For studies of other changes to the burning regime, see “Use rotational burning” and “Leave some areas unburned during prescribed burning”.
Bubová T., Vrabec V., Kulma M. & Nowicki P. (2015) Land management impacts on European butterflies of conservation concern: a review. Journal of Insect Conservation, 19, 805–821.
Glaves D.J., Morecroft M., Fitzgibbon C., Lepitt P., Owen M. & Phillips S. (2013) Natural England Review of Upland Evidence 2012 - The effects of managed burning on upland peatland biodiversity, carbon and water. Natural England Evidence Review, Number 004 (NEER004).
New T.R., Yen A.L., Sands D.P.A., Greenslade P., Neville P.J., York A. & Collett N.G. (2010) Planned fires and invertebrate conservation in South East Australia. Journal of Insect Conservation, 10, 567–574.
Swengel A.B. (2001) A literature review of insect responses to fire, compared to other conservation managements of open habitat. Biodiversity and Conservation, 10, 1141–1169.
Tucker G. (2003) Review of the impacts of heather and grassland burning in the uplands on soils, hydrology and biodiversity (ENRR550). Natural England (English Nature) report.
Vogel J.A., Koford R.R. & Debinski D.M. (2010) Direct and indirect responses of tallgrass prairie butterflies to prescribed burning. Journal of Insect Conservation, 14, 663–677.
Supporting evidence from individual studies
A replicated, controlled, before-and-after study in 1988–1995 in a tropical savannah and floodplain reserve in Northern Territory, Australia (Andersen & Müller, 2000) found that management with early season burning or no burning increased the abundance of caterpillars, but late season burning did not. After 2–5 years of burning, the abundance of caterpillars increased at sites with early (before: 1; after: 4 individuals) or no burning (before: 5; after: 8 individuals) but remained similar at sites with late burning (before: 3; after: 3 individuals). From 1990–1994, one of three fire regimes was applied annually to each of nine 15–20 km2 compartments across a 670-km2 area: early fires (lit early in dry season in May/June, equivalent to usual conservation management); late fires (lit late in dry season in September/October, equivalent to unmanaged wildfires); and unburned (no fires). Fire was excluded from all plots for 1–2 years prior to the experiment. Caterpillars were sampled by pitfall trapping and sweep-netting. Pitfall traps were set for 48 hours every November and August from 1988–1994, using 15 traps (10 m apart) per 40 × 20 m plot, with two plots/compartment, one in poorly-drained woodland and one in well-drained forest. Sweep-netting was conducted every February and May from 1989–1995, using five parallel transects of 20 sweeps each, spaced 5 m apart, over the trapping grid.Study and other actions tested
A replicated, paired, controlled study in 1993–1997 in 15 oak savannas in Wisconsin, USA (King 2003) found that burning grassland in summer or autumn did not increase Karner blue butterfly Lycaeides melissa samuelis abundance compared to either unmanaged or mown grasslands. The density of Karner blue was similar on both summer burned (31–186 individuals/ha) and paired, unburned (35–101 individuals/ha) grasslands, and on autumn burned (22–478 individuals/ha) and paired, unburned (14–179 individuals/ha) grasslands. Karner blue density was also similar on three summer burned (36–213 individuals/ha), three summer mown (46–111 individuals/ha) and three unmanaged (43–119 individuals/ha) grasslands. Fifteen restored oak savannas were burned on average every 3.5 years for 19–33 years prior to 1993. In 1994, four grasslands (1–11 ha) were summer burned in July and two grasslands (0.5–19.2 ha) were autumn burned in November. In winter 1993–1994, woody vegetation was removed with chainsaws on three additional grasslands, and these sites were then cut with a rotary mower in August 1994. Six control grasslands received no burning or mowing. In July–August 1993–1997, butterflies were surveyed three times/grassland/year (>7 days apart) along transects placed 15 m apart.Study and other actions tested