Ordinal-Level Resilience of Invertebrates After Fire Events in Eucalypt Woodlands of South-Eastern Australia

Abstract

Fire disturbance is an integral part of many ecosystems. However, some taxa may not be resilient to the increasing size, intensity, and frequency of fire events due to climate change. We investigated how terrestrial invertebrate Ordinal-level community structure and the abundance of six Orders (Acarina, Araneae, Coleoptera, Collembola, Diptera, Hymenoptera: Formicidae) changed following three natural fire events over two decades (2007–2022) in Kangaroo Island and mainland South Australia. We collected invertebrates using two methods (pitfall traps and sweep nets) at four sites (two burnt and two unburnt) every 6 months, before and after three fire events (2007, 2019, 2021). Ordinal-level community structure generally showed signs of recovery nearing pre-fire conditions within 20–22 months post-fire. The pitfall samples showed increased abundance in Coleoptera, Diptera and Hymenoptera (Formicidae) following fire, and no change in Acarina abundance. The sweep net samples showed no recovery to pre-fire conditions on mainland South Australia, but recovery to baseline after 20–22 months on Kangaroo Island. There were significant shifts in invertebrate community structure across time-since-fire with a return to pre-fire conditions at burnt sites after 20–22 months. These findings demonstrate the apparent ordinal-level resilience of invertebrates in South Australian eucalypt woodlands, particularly of ground-dwelling species, but also point to Order specific differences that warrant future study.