Grazing impacts on moth diversity and abundance on a Scottish upland estate

Maintain upland heath/moorland

A replicated, randomized, controlled study in 2003–2007 on an upland estate in Scotland, UK (Littlewood 2008, same experimental set-up as 1) found that ungrazed and lightly grazed plots had a higher abundance and species richness of moths than plots grazed at a commercial stocking densities. Plots grazed by sheep at low density had a higher abundance (52 individuals/night) and species richness (12.3 species/night) of moths than plots grazed by sheep at commercial densities (abundance: 34 individuals/night; richness: 10.6 species/night), or plots grazed by sheep and cattle at low density (abundance: 42 individuals/night; richness: 11.3 species/night), and were similar to ungrazed plots (abundance: 48 individuals/night; richness: 13.2 species/night). In January 2003, one of four grazing treatments was established on each of 24 plots (3.3 ha each) on a grazed acid grassland upland estate. The treatments were: low density sheep grazing (3 sheep/plot); commercial high density sheep grazing (9 sheep/plot); low density mixed grazing (2 sheep/plot plus two cows and calves for 4 weeks in autumn); ungrazed control. Moths were sampled between June and October 2007 using four 15 W light traps placed randomly within plots of each treatment, for six or seven sample nights/plot.

(Summarised by: Andew Bladon)

Use mixed stocking

A replicated, randomized, controlled study in 2003–2007 on an upland estate in Scotland, UK (Littlewood 2008, same experimental set-up as 2) found that plots grazed with sheep and cattle at low density had a lower abundance of moths and fewer moth species than plots grazed with sheep only at low density, but more moths than plots grazed by sheep at commercial stocking densities. On mixed grazing plots, both moth abundance (42 individuals/night) and species richness (11.3 species/night) were lower than on sheep-only plots grazed at the same low density (abundance: 52 individuals/night; richness: 12.3 species/night) and ungrazed plots (abundance: 48 individuals/night; richness: 13.2 species/night), but higher than on sheep-only plots grazed at commercial densities (abundance: 34 individuals/night; richness: 10.6 species/night). In January 2003, one of four grazing treatments was established on each of 24 plots (3.3 ha each) on a grazed acid grassland upland estate. The treatments were: low density mixed grazing (2 sheep/plot plus two cows and calves for 4 weeks in autumn); low density sheep grazing (3 sheep/plot); commercial high density sheep grazing (9 sheep/plot); ungrazed control. Moths were sampled between June and October 2007 using four 15 W light traps placed randomly within plots of each treatment, for six or seven sample nights/plot.

(Summarised by: Andrew Bladon, edited from Farmland Synopsis)

Reduce grazing intensity on grassland by reducing stocking density

A replicated, randomized, controlled study in 2003–2007 on an upland estate in Scotland, UK (Littlewood 2008, same experimental set-up as 2) found that lightly grazed plots had a higher abundance and species richness of moths than plots grazed at a commercial stocking density. Plots grazed by sheep at low density had a higher abundance (52 individuals/night) and species richness (12.3 species/night) of moths than plots grazed by sheep at commercial densities (abundance: 34 individuals/night; richness: 10.6 species/night), or plots grazed by sheep and cattle at low density (abundance: 42 individuals/night; richness: 11.3 species/night), and were similar to ungrazed plots (abundance: 48 individuals/night; richness: 13.2 species/night). In January 2003, one of four grazing treatments was established on each of 24 plots (3.3 ha each) on a grazed acid grassland upland estate. The treatments were: low density sheep grazing (3 sheep/plot); commercial high density sheep grazing (9 sheep/plot); low density mixed grazing (2 sheep/plot plus two cows and calves for 4 weeks in autumn); ungrazed control. Moths were sampled between June and October 2007 using four 15 W light traps placed randomly within plots of each treatment, for six or seven sample nights/plot.

(Summarised by: Andrew Bladon, edited from Farmland Synopsis)

Cease grazing on grassland to allow early succession

A replicated, randomized, controlled study in 2003–2007 on an upland estate in Scotland, UK (Littlewood 2008, same experimental set-up as 12) found that ungrazed plots had a higher abundance and species richness of moths than plots grazed by sheep at a commercial stocking rate, or sheep and cattle at low density, but were similar to low density sheep-grazed plots. After four years, ungrazed plots had a higher abundance (48 individuals/night) and species richness (13.2 species/night) of moths than plots grazed by sheep at commercial densities (abundance: 34 individuals/night; richness: 10.6 species/night), or plots grazed by sheep and cattle at low density (abundance: 42 individuals/night; richness: 11.3 species/night), but were similar to low density sheep-grazed plots (abundance: 52 individuals/night; richness: 12.3 species/night). In January 2003, one of four management regimes was established on each of 24 plots (3.3 ha each) on a grazed acid grassland upland estate. The treatments were: no grazing; commercial high density sheep grazing (9 sheep/plot); low density mixed grazing (2 sheep/plot plus two cows and calves for 4 weeks in autumn); and low density sheep grazing (3 sheep/plot). Moths were sampled between June and October 2007 using four 15 W light traps placed randomly within plots of each treatment, for six or seven sample nights/plot.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)

Maintain upland heath/moorland

In the same randomized, replicated, controlled trial (described in (Dennis et al. 2008), more moths (Lepidoptera) and moth species were found on ungrazed and lightly-grazed plots than on plots grazed at a commercial stocking rate (Littlewood 2008). Low-intensity sheep grazing and ungrazed treatments produced the highest number of moths (on average 52 moths/night and 48 moths/night, respectively) and moth species (on average 12.3 species/night; 13.2 species/night). Fewest moths (on average 34 moths/night) and moth species (on average 10.6 species/night) were found under the commercial grazing treatment. Grazing treatments began in January 2003 and moths were sampled between June and October 2007 using a randomly-placed 15W light trap for six or seven sample nights per plot.