Managing the Threat Program © BUSHFIRE CRC LTD 2010 Ten years post-wildfire recovery and health of Eucalypt forests and woodland in the Sydney Basin, Australia: Using remotely sensed vegetation indices Jessica Heath1*, Chris Chafer2, Tom Bishop1, Floris Van Ogtrop1 1 Faculty of Agriculture, Food and Natural Resources, University of Sydney, New South Wales 2 Sydney Catchment Authority, New South Wales *Contact details: [email protected] INTRODUCTION RESULTS The response of vegetation after a wildfire is •Figures 2-5 provide an example of the NDVI, NDVIc and NBR* for the Nattai subcatchment dependent on factors such as fire intensity and (1990/91- 2009/10), respectively. vegetation type. The majority of post-wildfire vegetation response studies conducted in Victoria, 1 NDVI •A obvious decline in the NDVI, NDVIc and NBR occurs at the time of wildfire (2001/2002 Australia, have been in communities dominated by 0.8 obligate seeders. These studies have found that there is summer). 0.6 a considerable delay in species germination due to a Extreme •The pattern of NDVI, NDVIc and NBR shows 0.4 Very high delay in water uptake by the seed bank. These studies High good vegetation recovery within two-three NDVI value 0.2 Moderate do not represent the response of vegetation in the Low years post-wildfire. Negliglible Sydney Basin, which is dominated by obligate 0 •NDVI, NDVIc and NBR patterns are similar to resprouter species. the Southern Oscillation Index (SOI) (Fig. 5) and rainfall (Fig. 6) pattern during the study period. RESEARCH AIMS Fig 2. Nattai River subcatchment NDVI values To determine if vegetation in the Sydney Basin recovers NDIVc 0.7 0.8 NBR within 8 years post-wildfire. 0.6 0.6 0.5 0.4 0.4 STUDY AREA 0.3 NDVIc 0.2 Four burnt sub-catchments: Burke River, Glenbrook 0.2 Creek, Erskine Creek and Nattai River (Fig. 1). 0.1 NBR values 0 0 -0.2 Three unburnt sub-catchments: Grose River, Kedumba River and Kowmung River (Fig. 1). Fig 4. Nattai River subcatchment NBR values Grose River Fig. 1 Fig 3. Nattai River subcatchment NDVIc values Kedumba River SOI data for study period Rainfall Glenbrook Creek 20 Kowmung 15 River 15 5 Erskine Creek Sy 10 d SOI -5 Lake ne -15 5 Burragorang y (ML) year per -25 0 Nattai River Average weekly rainfall Study area Burke Fig 5. SOI data 1991-2009 Fig 6. Average weekly rainfall per year 1991-2009 River METHODOLOGY CONCLUSION •Similar trends in vegetation cover occurs for all burn severities across the Landsat imagery Fire severity map Nattai River subcatchment in the post-wildfire period. •According to this study, wildfire has no considerable long-term affects on Atmospheric correction vegetation in the Sydney Basin, as the results suggest that vegetation recovers within three-five years post-wildfire. 5000 random sampling •Further studies need to be conducted to assess the relationship between NDVI/ NDVIc/ NBR points vegetation response and water yield recovery post-wildfire. References: 50 random sampling ESRI, 2009. ArcGIS. points per severity Bureau of Meteorology (BOM), 2012. Climate Glossary. http://www.bom.gov.au/climate/glossary/soi.shtml. Accessed 02/03/2012. Acknowledgments: The authors would like to thank Bushfire CRC and Sydney Catchment Authority Extract/ analyse data for their support. *NDVI: Normalized Difference Vegetation Index NDVIc: Corrected Normalized Difference Vegetation Index NBR: Normalized Burn Ratio .