Thursday, August 9, 2007
Exhibit Halls 1 and 2, San Jose McEnery Convention Center
The grasslands of California's Mediterranean climatic region are unique because they occur within a region where precipitation falls only during the cold part of the year, they have a very strong representation of annual species in their flora, and they have undergone a large-scale replacement of native species by European ones over the past 150 years. For more than twenty years, land managers and ecologists have been testing and applying prescribed fire as a method of restoring native vegetation and suppressing non-native species in California grasslands. We conducted a meta-analysis on more than twenty-five studies of grassland fires and prescribed burns in California grasslands. We derive general fire effects for the first three post-burn years, by life form/origin groups (non-native annual grasses, native perennial grasses, native forbs, and non-native forbs) and for selected species. We investigated factors influencing success such as climate, fire season, grazing, and burn frequency. Although some studies showed positive outcomes, overall success was short-term and variable. Our results show that typically native and exotic forbs increase, and non-native annual and native perennial grasses temporarily decrease. Except for non-native forbs, these effects may last only a couple of years, suggesting that an increase in non-native forbs may be the only long-term effect of fire. However, data for native perennial grasses is too limited to draw conclusions about long-term effects.
