Use prescribed fire to maintain or restore disturbance in forests
Overall effectiveness category Awaiting assessment
Number of studies: 3
Background information and definitions
Although many species of butterflies and moths are found in woodland, most prefer areas with open glades or a sparse understorey, where light can penetrate and enable flowering plants to grow, as well as providing areas for basking. One option for opening up dense areas of woodland is to use prescribed burning. Although destructive in the short-term, with 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). 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 using prescribed burning in naturally open habitats, see “Use prescribed fire to maintain or restore disturbance in grasslands or other open habitats”. For other options for reducing the density of woodlands, see “Habitat restoration and creation – Clear or open patches in forests”, “Habitat restoration and creation – Coppice woodland”, “Habitat restoration and creation – Thin trees within forests” and “Habitat restoration and creation – Create young plantations within mature woodland”.
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.
Supporting evidence from individual studies
A site comparison study in 1998 in two pine forests in Arizona, USA (Waltz & Covington 1999) found that a forest restored by prescribed burning and thinning young trees had a higher abundance and species richness of butterflies than an unrestored forest. Two years after burning and thinning, the restored forest had a higher abundance (6–46 individuals/visit) and species richness (3–11 species/visit) of butterflies than the unrestored forest (abundance: 0–7 individuals/visit; richness: 0–4 species/visit). One species, the checkered white Pieris protodice, was only found in the restored forest, but another, the California sister Limenitis bredowii, was only found in the unrestored forest. In 1996, a 40-acre ponderosa pine Pinus ponderosa forest was burned and thinned (pole-sized trees removed) to reopen the dense understorey. An adjacent forest was not restored. From May–July 1998, butterflies were surveyed six times (every two weeks) along a single 450-m transect in each forest.Study and other actions tested
A replicated, controlled study in 1998–1999 in two upland coniferous forest reserves in Oregon and California, USA (Huntzinger 2003) found that sites subjected to prescribed burning had more species of butterfly than unburned sites. In forest patches which had been burned once in the last 1–19 years, there were more species of butterfly (11–14 species/patch) than in patches not burned for at least 20 years (4–7 species/patch). There were also more species in burned “fuel-break” corridors (16 species/site) than in unburned corridors (1 species/site) and in riparian strips burned in the last 1–13 years (25 species/site) than in unburned strips (10 species/site). Butterfly species diversity was 0.5–8 times higher in the burned habitats than the unburned habitats (see paper for details). In Oregon, five upland forest patches were burned once between 1991 and 1997, and five patches were unburned since at least 1978. Five wide, shaded, corridors of thinned vegetation (“fuel breaks”) were burned and four were unburned (no dates given). In California, five upland forest patches were burned once between 1980 and 1998, and seven patches were unburned. Four riparian strips were burned once from 1986–1998, and five strips were unburned (no date given). Butterflies were surveyed along one 240-m transect/site, six times from late June–August 1998 in Oregon, and five times from late June–August 1999 in California.Study and other actions tested
A replicated, randomized, paired, controlled, before-and-after study in 1997–2001 in a pine forest in Arizona, USA (Waltz & Covington 2004) found that forests restored by prescribed burning and thinning had a higher abundance and species richness of butterflies than unrestored forests. One and two years after burning and thinning, restored forests had a higher butterfly abundance (48–132 individuals/unit) and species richness (7–16 species/unit) than unrestored forests (abundance: 10–42 individuals/unit; richness: 4–10 species/unit). Before restoration, there was no significant difference between forest marked for restoration (abundance: 23–50 individuals/unit; richness: 8–12 species/unit) and unrestored forest (abundance: 10–41 individuals/unit; richness: 5–13 species/unit). These results were primarily due to the abundance of species of blue (Lycaenidae) and white (Pieridae) butterflies (see paper for details). In 1997, four blocks within a 5,000-ha ponderosa pine Pinus ponderosa forest were each divided into two units (≤40-ha each). In autumn/winter 1999–2000, one randomly assigned unit/block was burned and thinned. The other units were not restored. From May–August 1997, 1998, 2000 and 2001, butterflies were surveyed six times/year (two-week intervals) along two or three 300-m transects/unit.Study and other actions tested