Cattle grazing impacts on annual forbs and vegetation composition of mesic grasslands in California

Published source details Hayes G.F. & Holl K.D. (2003) Cattle grazing impacts on annual forbs and vegetation composition of mesic grasslands in California. Conservation Biology, 17, 1694-1702.
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This study is summarised as evidence for the following.

	Action	Category
	Other biodiversity: Use grazers to manage vegetation Action Link

Other biodiversity: Use grazers to manage vegetation

A replicated, paired site comparison in 2000–2001 in coastal grasslands in central California, USA, found more plant species in cattle-grazed sites, compared to ungrazed sites, in three of eight groups, in at least one year, but found fewer plant species in two groups in one year. Cover of five groups varied between grazed and ungrazed sites. Plants: More species of native and non-native annual non-grass plants were found in grazed sites, compared to ungrazed sites (native: 6–8 vs 1–4 species/site; non-native 12–16 vs 7–12). More species of non-native annual grasses were found in grazed sites, compared to ungrazed sites, in one of two years (9 vs 7). Fewer species of native perennial non-grass and grass plants were found in grazed sites, compared to ungrazed sites, in one of two years (non-grass: 11 vs 16; grass: 4 vs 5). Three other groups showed no differences. Cover of three groups was higher in grazed sites (native annual non-grasses: 9–14 vs 1–3 m²/ha; non-native annual non-grasses: 73–76 vs 54–62 intercepts/250 sampling points; non-native perennial non-grasses: 45–77 vs 32–54), and cover of another group was higher in one of two years (non-native annual grasses: 170 vs 130). One group had lower cover in grazed sites (25–26 vs 41–52). Cover of three other groups did not vary. Vegetation height was lower in grazed sites (13–15 vs 25–27 cm). Methods: Between 17 (2000) and 25 (2001) pairs of sites were studied along the coast (670 km). One site in each pair had been grazed by cattle for at least 10 years, and the other had not been grazed for five years. Vegetation was sampled in March–June (five transects/site).