α- and β-diversity in moth communities in salt marshes is driven by grazing management

Published source details Rickert C., Fichtner A., van Klink R. & Bakker J.P. (2012) α- and β-diversity in moth communities in salt marshes is driven by grazing management. Biological Conservation, 146, 24-31.
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This study is summarised as evidence for the following.

	Action	Category
	Reduce intensity of livestock grazing: brackish/salt marshes Action Link
	Employ areas of semi-natural habitat for rough grazing (includes salt marsh, lowland heath, bog, fen) Action Link
	Exclude or remove livestock from historically grazed brackish/salt marshes Action Link

Reduce intensity of livestock grazing: brackish/salt marshes

A controlled study in 1991–2009 on a salt marsh in northern Germany (Rickert et al. 2012) found that less intensely grazed paddocks generally had higher plant species richness, greater vegetation cover and taller vegetation than more intensely grazed plots. After 16–18 years, lightly grazed paddocks had higher plant species richness (12.2 species/m²) than a moderately grazed paddock (9.9 species/m²), which had higher plant species richness than a heavily grazed paddock (6.7 species/m²). Total vegetation cover was greater in the lightly and moderately grazed paddocks (86–89%) than in the heavily grazed paddock (82%). Likewise, the vegetation canopy was taller in the lightly and moderately grazed paddocks (13.7–14.0 cm) than in the heavily grazed paddock (6.3 cm). Vegetation cover (but not canopy height) was also lower in the lightly grazed paddock than in the moderately grazed paddock. The study also reported cover of the dominant species in each paddock (see original paper for data). Methods: The study used three paddocks on a coastal salt marsh (historically heavily grazed by sheep). From 1991, the paddocks were grazed each summer at different intensities: one lightly (1–2 sheep/ha), one moderately (3–4 sheep/ha) and one heavily (10 sheep/ha). Vegetation was surveyed every three weeks in summer 2007–2009, in a total of thirty 1-m² quadrats/paddock/year. All quadrats were at a similar elevation (±20 cm). The paddocks in this study were also used in (5).

(Summarised by: Nigel Taylor)
Employ areas of semi-natural habitat for rough grazing (includes salt marsh, lowland heath, bog, fen)

A controlled study in 1991–2009 in a saltmarsh in Schleswig-Holstein, Germany (Rickert et al. 2012, same experimental set-up as 6 and 9) found that lightly grazed and ungrazed saltmarsh supported more micro-moths than more intensively grazed saltmarsh. After 15–18 years of grazing, both the abundance and species richness of moths on a lightly grazed (abundance: light trap: 65.5, emergence trap: 7.1 individuals/trap; richness: light trap: 7.7, emergence trap: 1.3 species/trap) and an ungrazed marsh (abundance: light trap: 88.6, emergence trap: 6.0 individuals/trap; richness: light trap: 6.2, emergence trap: 1.8 species/trap) were higher than on a moderately grazed (abundance: light trap: 25.4, emergence trap: 2.3 individuals/trap; richness: light trap: 3.8, emergence trap: 0.6 species/trap) or heavily grazed marsh (abundance: light trap: 9.0, emergence trap: 0.2 individuals/trap; richness: light trap: 1.5, emergence trap: 0.1 species/trap). In 1991, four paddocks were established on a 1,050-ha saltmarsh and assigned to four grazing treatments: light (1–2 sheep/ha), moderate (3–4 sheep/ha) or heavy grazing (10 sheep/ha), and ungrazed (0 sheep/ha). From June–September 2006–2009, micro-moths were sampled using one 12 V actinic light trap/paddock on 6–9 nights/year (31 nights total). From April–October 2007–2009, micro-moths were sampled using a 1-m² steel emergence trap in each of three 150 × 20 m plots/paddock (>250 m apart). Traps were emptied weekly and repositioned every three weeks, therefore sampling 10 m²/plot/year.

(Summarised by: Andrew Bladon)
Exclude or remove livestock from historically grazed brackish/salt marshes

A controlled study in 1991–2009 on a salt marsh in northern Germany (Rickert et al. 2012) found that a paddock from which sheep had been removed contained taller vegetation than paddocks which remained grazed, and typically had higher vegetation cover and plant species richness. After 16–18 years, the vegetation canopy was taller in an ungrazed paddock (20 cm) than in all grazed paddocks (6–14 cm). In two of three comparisons, overall vegetation cover was greater in an ungrazed paddock (87%) than in grazed paddocks (lightly grazed: 86%; heavily grazed: 82%). In the other comparison, cover was lower in the ungrazed paddock (vs moderately grazed: 89%). In two of three comparisons, total plant species richness was greater in an ungrazed paddock (10.1 species/m²) than in grazed paddocks (moderately grazed: 9.9; heavily grazed: 6.7 species/m²). In the other comparison, richness was lower in the ungrazed paddock (vs lightly grazed: 12.2 species/m²). The study also reported cover of the dominant species in each paddock. For example, sea purslane Atriplex portulacoides was the most abundant species in the ungrazed paddock (27% cover) but not in grazed paddocks (<7–19% cover). Methods: The study used four paddocks on a coastal salt marsh (historically heavily grazed by sheep). From 1991, livestock were removed from one paddock. The other paddocks were grazed each summer: lightly (1–2 sheep/ha), moderately (3–4 sheep/ha), or heavily (10 sheep/ha). Vegetation was surveyed every three weeks in summer 2007–2009, in a total of thirty 1-m² quadrats/paddock/year. All quadrats were at a similar elevation (±20 cm). The paddocks in this study were also used in [12].

(Summarised by: Nigel Taylor)