Native Species Response to Goat Foraging in a Shrub-invaded California Coastal Grassland

John Inman, California State University, Monterey Bay


California coastal grasslands have been frequent targets of preservation efforts due to the habitat they provide for native perennial bunchgrasses, such as purple needlegrass (Stipa pulchra), which have been nearly completely replaced by non-native annual grasses in much of the state. Once protected from ecological disturbance, however, these grasslands become subject to invasion by coyote brush (Baccharis pilularis), potentially resulting in permanent loss of habitat. Goats have successfully been used to control woody vegetation in other contexts but to date there have been no studies published on using goats to restore ecological disturbance in coyote brush-invaded coastal grasslands. Land managers at Fort Ord in the central coast region of California conducted a field study to measure the groundcover responses of six taxa to repeated bouts of goat foraging in dense stands of coyote brush in an invaded grassland. There was decisive evidence that repeated bouts of goat foraging coincided with a 24% net decrease of coyote brush groundcover and a 37% net increase of annual grass groundcover in foraged plots relative to control plots, but no clear evidence of this relationship for other taxa. These results indicate that goat foraging is effective at reducing coyote brush groundcover but its ability to directly facilitate corresponding increases in bunchgrass is uncertain. Foraging should continue in areas of rapidly invading coyote brush while future research should examine how the intensity, duration, and seasonality of foraging can be managed to favor native species.