Utility of lenient grazing on agricultural grassland to promote in-field structural heterogeneity, invertebrates and bird foraging [BD5207: Extensive cattle grazing: what is the best approach to improve species-poor pastures for birds and invertebrates? (Phase 2)]

Published source details RSPB . (2016) Utility of lenient grazing on agricultural grassland to promote in-field structural heterogeneity, invertebrates and bird foraging [BD5207: Extensive cattle grazing: what is the best approach to improve species-poor pastures for birds and invertebrates? (Phase 2)]. Natural England report, Project BD5206/BD5207 RSPB Final Report to DEFRA/Natural England (RP00196).
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This study is summarised as evidence for the following.

	Action	Category
	Use rotational grazing Action Link
	Reduce grazing intensity on grassland by reducing stocking density Action Link

Use rotational grazing

A replicated, paired, controlled study in 2010–2012 in six permanent pasture fields in Devon, UK (RSPB 2016) found that rotationally grazed grassland initially had a higher abundance of invertebrates (including caterpillars) than continuously grazed grassland, but the effect disappeared over three years. In the first year, the number of “bird food invertebrates” was higher on rotational grassland (154 individuals/plot) than on continuously grazed grassland (112 individuals/plot). However, after two and three years, there was no significant difference between rotational (two years: 76; three years: 51 individuals/plot) and continuously grazed plots (two years: 78; three years: 42 individuals/plot). From April 2010–September 2012, six permanent pasture fields were divided into two 1-ha plots. One plot/pair was rotationally grazed by cattle, managed to keep sward height between 9–12 cm, and the other was continuously grazed, keeping the sward at 6–8 cm. None of the fields were fertilized during the trial. In July 2010–2012, invertebrates were sampled in 10 locations/plot using a Vortis suction sampler (ten 15-second samples over 0.19 m²) and sweep-netting (20 double sweeps with a 46-cm diameter net). Invertebrates <2 mm long were excluded from analysis.

(Summarised by: Andrew Bladon)
Reduce grazing intensity on grassland by reducing stocking density

A replicated, paired, controlled study in 2010–2012 in six permanent pasture fields in Devon, UK (RSPB 2016) found that grassland managed with reduced stocking density initially had a higher abundance of invertebrates (including caterpillars) than conventional grassland, but the effect disappeared over three years. In the first year, the abundance of “bird food invertebrates” was higher on grassland grazed at a reduced density (202 individuals/plot) than on grassland grazed conventionally (112 individuals/plot). However, after two and three years, there was no significant difference between reduced (two years: 97; three years: 48 individuals/plot) and conventionally grazed plots (two years: 78; three years: 42 individuals/plot). From April 2010–September 2012, six permanent pasture fields were divided into two 1-ha plots. One plot/pair was grazed by cattle at reduced stocking density, managed to keep sward height between 9–12 cm, and the other was grazed at conventional stocking density, keeping the sward at 6–8 cm. None of the fields were fertilized during the trial. In July 2010–2012, invertebrates were sampled in 10 locations/plot using a Vortis suction sampler (ten 15-second samples over 0.19 m²) and sweep-netting (20 double sweeps with a 46-cm diameter net). Invertebrates <2 mm long were excluded from analysis.

(Summarised by: Andrew Bladon)