Livestock grazing is an effective conservation tool for Californian coastal grassland ecology: An eight-year study on vegetation dynamics

Questions

Livestock grazing is an expanding land management tool for habitat and fuel management in California grassland ecosystems, despite mixed conclusions about its effects. Our study investigated the following questions:

• Does a targeted grazing regime promote grassland functioning by clearing bare ground and reducing dead litter cover?
• Does targeted grazing reduce grassland fuels?
• Does targeted grazing promote native species cover and diversity?
• Does targeted grazing reduce non-native, invasive species cover and diversity?

Location

The Santa Lucia Preserve, Carmel, California, USA.

Methods

Monitoring grazed and ungrazed treatment plots within 17 study sites, we surveyed the effects of a targeted grazing regime on bare ground cover, litter cover and depth, herb height, and diversity and cover of different native and non-native species groups over an eight-year period.

Results

On average, grazing successfully increased bare ground (by 2.8% cover), decreased litter depth (by 3.5 cm) and cover (by 12%), and decreased herb height (by 3.9 cm). Grazed plots had greater cover of native annual forbs (+1.2% cover), while decreasing invasive Bromus diandrus (by 6.0% cover). There was no difference in either native or non-native species diversity.

Conclusions

Targeted grazing can be an appropriate tool to accomplish conservation goals, including biomass management and canopy clearing, while improving native annual forbs without risk to native species as a whole. Further steps in adaptive management must examine how the application of grazing may be altered to further promote native species and to inhibit invasive species.