Year

2023

Degree Name

Bachelor of Science (Honours)

Department

School of Earth, Atmospheric and Life Sciences

Advisor(s)

Owen Price

Abstract

Prescribed fire is the predominant land management tool used across Australia’s temperate forests. However, little is known about the use of periodic, low-intensity prescribed fires over long-time frames and their effect on invertebrate communities. Most invertebrate species provide essential ecosystem services and are an essential component of global food chains. Despite their profound importance to ecosystems globally, invertebrates are often ignored entirely in fire research and generally lack incorporation into fire management and recovery plans. Prescribed fire usage is poised to increase in usage to mitigate the effects of damaging wildfires under a changing climate and so its impact on invertebrates should be assessed to determine if it provides sound ecological outcomes alongside human asset protection. A multi-method sampling approach using beating trays, leaf litter collections and a custom method of observing empty pitfall traps with scouting cameras was used in this study to measure invertebrate abundances at six sclerophyll and eucalypt forest sites on the NSW South Coast which had undergone a prescribed hazard reduction burn within the last 3 years. The aim of this project was to assess the immediate and short-term impacts on ground-dwelling, leaf-litter and lower-canopy utilising invertebrates following the application of a prescribed fire and to investigate their general recovery outcomes through the quantification of invertebrate assemblages at sites of varying time-since-fire (TSF) history and burn status (burnt vs. unburnt). This study was able to identify 7170 invertebrates representing 24 Ordinal taxon with Hymenoptera (55.58%), Araneae (21.52%), Collembola (9.34%), Isopoda (2.52%) and Diptera (2.41%) contributing 91.37% of all invertebrates sampled. This study identified four major responses of taxa. Firstly, Hymenoptera were relatively unaffected by fire, with highest abundances measured immediately following prescribed fire likely due to their soil-nesting behaviour which provides protection from fire and radiant heat. Secondly, Orthoptera, Collembola and Acari showed heavily reduced abundances at recently burnt sites, with a recovery spike observed within 3 years followed by population declines at 5+ years TSF. Despite non-significance for the Orthoptera, this trend is likely indicative of a successional response with these Orders showing a strong preference for an optimal post-fire habitat stage. Thirdly, Hemiptera, Isopoda, Coleoptera, Blattodea, Lepidopteran larvae and the Araneae all showed reduced abundances immediately following fire with increasing recovery observed from 3 years onwards. Finally, the Diptera and Amphipoda showed no distinct fire-related trends. This is likely due to high variability in abundances at sites coupled with overall low detection rates as a result of a lack of litter and reduced moisture content of soils. Overall, this thesis provides evidence for short-term fire effects (<3 >years) across a variety of invertebrate Orders, longer-term recovery trajectories (>5 years), successional responses of some taxa and highlights the importance of using fire practices that generate habitat mosaics with varying successional stages of vegetative regrowth to facilitate the short-term survival and longer-term persistence of invertebrates in response to prescribed fires.

FoR codes (2020)

310399 Ecology not elsewhere classified, 410205 Fire ecology, 410401 Conservation and biodiversity

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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.