Oral Presentation Australian Freshwater Sciences Society Conference 2022

The effects of fire on microinvertebrate eggbanks in three vegetation communities in the Gwydir wetlands, northern NSW (#4)

Ivor Growns 1 , Mark Southwell 2 , Sarah Mika 1 , Lindsey Frost 1 , Ben Vincent 1 , Zac Lewis 1 , Darren Ryder 3
  1. UNE, Armidale, NSW, Australia
  2. 2rog Consulting, Armidale
  3. Canberra University, Canberra

Wildfire is a common phenomenon in the Australian landscape and can affect floodplain wetlands during dry phases. Although common, the effects of wildfire are understudied both in Australia and overseas. We took replicate soil samples from burnt and unburnt locations in three vegetation communities including Typha reedbeds, Water couch marshlands and Coolabah woodlands following a wildfire in the Gwydir State Conservation Area in September 2019. We tested two hypotheses 1. That eggbanks will be detrimentally affected by fire resulting in a reduction in invertebrate abundance and taxa. 2. Invertebrates emerging from more frequently inundated soil, using vegetation community type as a surrogate, will have more individuals and taxa. Soil was wetted in replicate mesocosms and the emergent invertebrates identified and their density estimated after 28 days. A total of 15,443 invertebrates from 8 taxa was estimated from the mesocosms. Invertebrate abundance and number of taxa differed significantly between burnt and unburnt plots and vegetation communities. The interaction between the two factors, treatment and vegetation type, was not significant for either invertebrate abundance or number of taxa, suggesting the effects of burning were consistent regardless of vegetation type. Burning reduced invertebrate density and richness and more frequently inundated vegetation communities (Typha compared with Coolabah woodlands) harboured are greater number of taxa and invertebrates. Although exposure of wetland soil to burning immediately decreased invertebrate eggbank density and richness there appeared to be no long-term detrimental effects as indicated by routing sampling of microinvertebrates in the wetlands.