Individual study: Introducing cattle grazing to a noxious weed-dominated rangeland shifts plant communities
Davy J.S., Roche L.M., Robertson A.V., Nay D.E. & Tate K.W. (2015) Introducing cattle grazing to a noxious weed-dominated rangeland shifts plant communities. California Agriculture, 69, 230-236
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Other biodiversity: Use grazers to manage vegetation
A replicated, randomized, controlled, before-and-after study, in 2006–2011 in grasslands and oak woodlands in northern California, USA, found differences in the abundance of some plant species, and differences in the plant community, between grazed and ungrazed plots. One of two non-native plant species declined in grazed plots, compared to ungrazed plots, in dry years. Plants: One desirable forage species increased in grazed plots, but not ungrazed plots (change from 0% to 17% cover vs 1% to 0%). Another desirable forage species increased in both (change from 1% to 5–10% cover). By the end of the experiment, but not at the beginning, the plant community differed between grazed and ungrazed plots (results reported as ordination results). Cover of medusahead Elymus caput-medusae decreased in three dry years in grazed plots, but not in ungrazed plots (decrease from 48% to 22% cover vs increase from 44% to 52%). Overall, it decreased to similar levels in grazed and ungrazed plots (25–26%). Cover of yellow starthistle Centaurea solstitialis did not differ between grazed and ungrazed plots (8–18%). Two other non-native species that are poor forage increased in ungrazed plots, but not in grazed plots (ungrazed: increase from 0% to 5% and 0% to 8% cover; grazed: decrease from 2% to 0% and 1% to 0%). Methods: In 2006, rotational grazing at moderate stocking densities was started in 11 paddocks of 80–600 acres. Paddocks were grazed for up to two weeks in November–February and March–June. Paired 8 x 8 foot plots were established in each paddock and the plant community monitored in June 2006, 2009, and 2011.