Acacia shrubs respond positively to high severity wildfire: Implications for conservation and fuel hazard management.
High severity wildfires pose threats to human assets, but are also perceived to impact vegetation communities because a small number of species may become dominant immediately after fire. However there are considerable gaps in our knowledge about species-specific responses of plants to different fire severities, and how this influences fuel hazard in the short and long-term. Here we conduct a floristic survey at sites before and two years after a wildfire of unprecedented size and severity in the Warrumbungle National Park (Australia) to explore relationships between post-fire growth of a fire responsive shrub genera (Acacia), total mid-story vegetation cover, fire severity and fuel hazard. We then survey 129 plots surrounding the park to assess relationships between mid-story vegetation cover and time-since-fire. Acacia species richness and cover were 2.3 and 4.3 times greater at plots after than before the fire. However the same common dominant species were present throughout the study. Mid-story vegetation cover was 1.5 times greater after than before the wildfire, and Acacia species contribution to mid-story cover increased from 10 to 40%. Acacia species richness was not affected by fire severity, however strong positive associations were observed between Acacia and total mid-story vegetation cover and severity. Our analysis of mid-story vegetation recovery showed that cover was similarly high between 2 and 30years post-fire, then decreased until 52years. Collectively, our results suggest that Acacia species are extremely resilient to high severity wildfire and drive short to mid-term increases in fuel hazard. Our results are discussed in relation to fire regime management from the twin perspectives of conserving biodiversity and mitigating human losses due to wildfire.
Centre for Environmental Risk Management of Bushfires, University of Wollongong, NSW 2522, Australia. Electronic address: gordonc@uow.edu.au.
Christopher E
CE
Gordon
Centre for Environmental Risk Management of Bushfires, University of Wollongong, NSW 2522, Australia.
Owen F
OF
Price
Science Division, NSW Office of Environment and Heritage, Hurstville, NSW 2220, Australia.
Elizabeth M
EM
Tasker
Science Division, NSW Office of Environment and Heritage, Hurstville, NSW 2220, Australia; Centre for Sustainable Ecosystem Solutions, University of Wollongong, NSW 2522, Australia.
Andrew J
AJ
Denham
Fuel load; Stable state-change; Vegetation cover; Wambelong fire; Warrumbungle national park; Wildfire