Document: JAN-3-35-4

Factors affecting successful control of French and Scotch broom and restoration of native communities in coastal California grasslands.

ALEXANDER, J.M.F.*, C.M.D'ANTONIO and K.A.HAUBENSAK

University of California, Berkeley ¹

Abstract:
French broom (Genista monspessulana ) and Scotch broom (Cytisus scoparius) are aggressive, invasive, nitrogen-fixing shrubs from Europe that are now abundant in California. Once established, broom plants form dense, practically monotypic stands and spread into areas dominated by native plants. In an effort to restore native plant communities, land managers control broom through cutting, pulling, and prescribed burning. We surveyed the community composition of areas that had received different numbers and types of management treatments to assess which environmental factors are important in effectively controlling broom and restoring native plants. We measured soil characteristics, including moisture, depth, and total carbon and nitrogen, and environmental variables such as slope, aspect, rainfall, and elevation, as well as site history variables. Using a canonical correspondence analysis, we found soil carbon and nitrogen, and number of burn treatments were useful in separating species groupings on the first axis, and time since last burn was important in further separating groups on the second axis. Repeated burning did reduce broom abundance aboveground, but the plant community replacing broom was composed largely of exotic herbaceous species.

Keywords: nitrogen-fixer, restoration, invasion, grasslands

This abstract is being presented at: 10:30 AM in session:
RESTORATION ECOLOGY AND INVASIONS