Year

2023

Degree Name

Bachelor of Environmental Science (Honours)

Department

School of Earth, Atmospheric and Life Sciences

Advisor(s)

Jeffrey Kelleway

Abstract

The 2019-20 bushfire season impacted a range of ecosystems across Australia, including several coastal vegetation types that have not been subject to burning historically. In the Clyde River estuary of southern New South Wales (NSW), mangrove species Avicennia marina and Aegiceras corniculatum were burnt in the Black Summer bushfires. The slow recovery of these poorly fire adapted species reflects the lasting impacts of the event. This study aimed to quantify the ongoing processes, patterns, and capabilities of post-fire mangrove regeneration for both species in the Clyde River estuary. Assessments of fire-affected mangroves were undertaken through field data collection and analysis of remotely sensed aerial imagery. Long term study site Chinamans Point exhibited limited resprouting of severely impacted A. marina, for the third year of monitoring. At Mays Road and Buckenbowra entrance, change detection analyses suggested only 19 – 28% of the total defoliated mangroves exhibited regrowth. Expanses of landward A. marina and A. corniculatum were determined to be dead at both sites, with minimal resprouting observed farther from the terrestrial forest. Dead mangroves were dominantly located at the highest elevations of the upper intertidal zone within all surveyed sites, reflecting the landward position and proximity to fire spread. Mangrove seedlings planted in April at Chinamans Point and Mundarlow Creek were monitored 3 months after placement, and most seedlings had been dislodged from the plots. Natural recruitment of A. marina at these two sites appears to be concentrated at the highest elevations rather than across the entire upper intertidal zone. The results from this study emphasize the need to trial different planting methodologies to improve future success rates. A. marina and A. corniculatum have shown some capability in recovering from a severe bushfire, although resprouting is not prevalent across sites and is occurring on a slower timescale than typical of fire-adapted ecosystems. Resprouting was observed in both species, although resprouting A. marina were more common than A. corniculatum across surveyed sites. The results of this study can offer insights into the resilience of mangroves in recovering from extreme disturbance events and inform longer-term management of mangrove communities.

FoR codes (2020)

410102 Ecological impacts of climate change and ecological adaptation, 410205 Fire ecology, 410402 Environmental assessment and monitoring

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.