Cattle Grazing Impacts on Annual Forbs and Vegetation Composition of Mesic Grasslands in California

Abstract

Livestock grazing represents a major human alteration of natural disturbance regimes in grasslands throughout the world, and its impacts on plant communities have been highly debated. We investigated the impact of cattle grazing on the California coastal prairie plant community with a focus on native annual forbs, a number of which are of conservation concern. In spring 2000 and 2001, we surveyed the vegetation community composition, vegetation structure, and soil chemical parameters at 25 paired grazed and ungrazed sites over a 670-km range of the ecosystem. Native annual forb species richness and cover were higher in grazed sites, and this effect was concomitant with decreased vegetation height and litter depth. Soil properties explained less of the variation. Exotic annual grass and forb cover were higher in grazed sites. Native grass cover and species richness did not differ in grazed and ungrazed sites, but cover and species richness of native perennial forbs were higher in ungrazed sites. Our results suggest that cattle grazing may be a valuable management tool with which to conserve native annual forbs in the ecosystem we studied but that grazing differentially affects the various life-history guilds. Therefore, land managers must focus on creating a matrix of disturbance regimes to maintain the suite of species native to these mesic grasslands. The results of this and other studies highlight the importance of considering the adaptation of vegetation communities to disturbance in making recommendations for grazing management. Impactos del Pastoreo de Ganado sobre Hierbas Anuales y la Composición Vegetal de Pastizales Mésicos en CaliforniaResumen: El pastoreo de ganado representa una importante alteración humana de los regímenes de perturbación natural en los pastizales del mundo, y sus impactos sobre las comunidades vegetales han sido ampliamente debatidos. Investigamos el impacto del pastoreo de ganado sobre la comunidad de plantas en la pradera costera de California conénfasis en hierbas nativas anuales, de las cuales varias son de preocupación para la conservación. En la primavera de 2000 y 2001, estudiamos la composición de la comunidad vegetal, estructura de la vegetación y parámetros químicos del suelo en 25 pares de sitios con pastoreo y sin pastoreo en una extensión de 670 km del ecosistema. La riqueza y cobertura de hierbas nativas anuales fueron mayores en sitios pastoreados, y este efecto fue concomitante con una disminución en la altura de la vegetación y la profundidad de la hojarasca. La variación fue menos explicada por las propiedades del suelo. La cobertura de pasto y hierbas exóticas fue mayor en sitios con pastoreo. La cobertura y riqueza de especies de pasto nativo no difirió en sitios con y sin pastoreo pero la cobertura y riqueza de especies de hierbas perennes nativas fue mayor en sitios no perturbados. Nuestros resultados sugieren que el pastoreo de ganado puede ser una valiosa herramienta de gestión para conservar hierbas nativas anuales en el ecosistema que estudiamos pero que el ...

Not novel, just better: competition between native and non-native plants in California grasslands that share species traits

“…Prescribed fire and grazing are among the mostoften applied management strategies in grassland ecosystems for the purposes of restoration of native biodiversity (Bakker 1989;Hayes and Holl 2003;Corbin et al 2004;Huntsinger et al 2007;Reiner 2007). Often, such treatments are specifically timed to take advantage of the earlier growth and flowering time of the exotic annual species compared to the native perennials-e.g., grazing in March rather than June (Love 1944;Huntsinger et al 2007).…”

Postbreeding Movement and Habitat Use of the Plateau Brown Frog, Rana kukunoris, in a High-Elevation Wetland

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Introducing cattle grazing to a noxious weed-dominated rangeland shifts plant communities

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