Differential resilience of invertebrates to fire



Fires are natural to ecosystems in many parts of the world, yet few studies have examined multi-taxa invertebrate responses to these fires. We sampled a wide range of invertebrate taxa and feeding guilds at sites 3 months, 1 year and 3 years after fire, and in unburned control sites at the same time. A range of invertebrate sampling techniques was used on Table Mountain, in the Cape Floristic Region biodiversity hotspot, an area prone to natural and human-induced fires. Sampling time differences strongly affected the composition of the whole assemblage, with fire having a major additional influence. Assemblages showed differential resilience to fire, especially in terms of species richness and abundance. One year after fire, the burned sites had the most compositional differences for the surface-active species compared to control sites, while after 3 years, these sites were similar. Aerial assemblages were very different 3 years after burning, especially the pollination guild. Furthermore, these 3-year-old burned sites had the most unique species, suggesting that burning and longer-term recovery is important for overall diversity. Some components of the invertebrate assemblage were remarkably resilient to fire (particularly ants), while others were far more conservative (pollinators). Nevertheless, fire allows new species to enter the ecosystem and can thus be used to promote local biodiversity if used appropriately. Ants alone should not be used to represent the whole invertebrate assemblage as they do not represent the more fire-prone groups. A cross-section of functional guilds is recommended in invertebrate recovery/fire management conservation programmes. These results have general significance in that a variety of feeding guilds need to be sampled when monitoring invertebrate responses to fire.