Researchers from UC Irvine and San Diego State University Friday announced study results that may provide insight on how native plant habitats can more successfully recover from wildfires.
Findings suggest that coastal sage scrub, Southern California's dominant native plant, is generally resilient to wildfire and can reach pre-burn cover within four years, but it is vulnerable to drought conditions.
Researchers also found that wildlife managers can assist scrub and other native plant species growth by removing non-native species, as such plants grow abundantly in burn areas and risk crowding out native types.
The study, recently published in the Ecosphere journal, was informed by research conducted on Orange County plant communities following the 2007 fire near Santiago Canyon and the 2011-2015 California drought. Research was made possible, in part, by 10 years of vegetation monitoring funded by The Nature Conservancy and the Natural Communities Coalition.
"Our results demonstrated the resilience of native shrub cover to fire along with the susceptibility of dense native shrubs and native grasses to drought and increases in non-native species," said study author Sarah Kimball, a researcher at UCI's Center for Environmental Biology. "They also highlight that land monitoring efforts sponsored by institutions like The Nature Conservancy can help ecologists test hypotheses regarding long-term dynamics in community vegetation."
Data also indicated that Orange County grasslands are heavily invaded by non-native species. Restoration of those areas should be a priority, researchers said.
The study's authors also found that native wildflowers had the highest diversity during wet years that were preceded by dry years, which suggests they face less competition from non-native grasses, which are also typically abundant in wet years.
As a follow-up to the recently completed study, experimental land plots have been set up to test whether removal of non-natives during the first few post-fire years will lead to lower non-native cover in burned areas.
