Thursday, August 9, 2007
Exhibit Halls 1 and 2, San Jose McEnery Convention Center
Widespread conversion of native habitats to non-native grasslands has caused long-lasting habitat homogenization and loss of biodiversity in California. Maritime chaparral is of particular conservation concern. Of limited areal extent, it is distributed in a series of isolated locations, each characterized by its own endemic species. We developed a model experimental plan to facilitate restoration of this community type and tested it on a 25-acre site dominated by introduced annual grasses since at least the 1930s, with a history of dry-farming and cattle grazing. Characteristic endemics at this location include four large evergreen shrubs, Arctostaphylos rudis, A. purissima, Ceanothus impressus and C. cuneatus var. fascicularis. In 1997, we erected a double fence intended to exclude cattle and deer; sowed locally-collected seed of native shrubs; established 60 enclaves (clusters) into which we transplanted native shrubs and oaks propagated from local seed or cuttings and fitted them with alternative protective treatments. We distributed raptor perches throughout the site to facilitate predation on small mammals. Despite heavy deer browsing, pocket gopher activity, and a record-setting, plant-killing freeze, 37 % of the 6,300 transplants survived through 2003. Only one species, Lupinus chamissonis, established extensively from seed. This large short-lived shrub grew rapidly and even after death helped protect many of the transplants from browsing. For most transplants, a combination of mesh tubes or tree shelters, weed mat, and “gopher cages” increased survival and growth. Seeding of other species was unsuccessful, perhaps due to our inability to burn during site preparation as planned.
