Burning is not a grassland management method much used in lowland Britain, although limestone grasslands in the Cotswolds were traditionally managed by burning ('swaling') and fire is used very locally elsewhere. In some regions, e.g. North America, burning of grasslands is regarded a normal and natural management method. In this study, hemipteran communities on areas of recently burned carboniferous limestone grassland in Derbyshire (central England) were compared with unburned areas.
In spring 1972, two patches of grassland on the south-facing slope of Lathkill
Dale (OS Ref. NGR SK 175655) was burnt. One (1-1.5 ha) was burnt (unusually late) on or near 8 May (previously burnt mid-February 1965); the second (0.5-1 ha) on or near 15 April (previously burnt 1965).
Samples of Heteroptera (e.g. sheildbugs) and Auchenorhyncha (leafhoppers etc.) were taken in September 1972 from three paired burnt and adjacent unburnt areas. A paired sample was also taken from a south west-facing grassland at nearby Monks Dale (SK 133751); here, an area had been burnt 'recently' (date and last date when previously burnt, had not been recorded). The samples taken from burnt and unburnt areas were about 20 m apart.
In the total of eight samples taken at Lathkill and Monks Dales, significantly larger numbers of species (both of Heteroptera and Auchenorhyncha) were recorded from the unburnt grassland areas and species-diversity was significantly greater.
Heteroptera: Ten Heteroptera species were recorded in the samples. The average number of species in burnt sward was 0.5 and in unburnt 4.0. Species-diversity was zero for the burnt plots (due to the low number of species recorded) and averaged 1.09 for unburnt grassland.
Auchenorhyncha: Thirty-one species were recorded. At Lathkill few leafhoppers were recorded in burnt compared with unburnt grassland (average 17 vs. 175). Conversely, at Monks Dale more were recorded from the burnt than from the unburnt area (123 vs. 74; it should be remembered that the burn date here was though, unknown). However, overall more species were recorded in unburnt compared to burnt sward (average 14.3 vs. 7.5) and species diversity was higher (average diversity 2.5 vs. 1.5). Only one of the few species known to be associated with short, frequently disturbed grasslands was recorded; a single Macrosteles laevis.
These preliminary investigations show that spring burning severely reduced abundance, number of species and species diversity (over at least six months) of Heteroptera and Auchenorhyncha. Burning appears a catastrophic event from which recovery may be slow, as indicated by poor colonization from the relatively nearby (20 m distant) unburnt areas.
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