Oral Presentation Australian Society for Limnology Congress 2013

The disturbance trifecta –drought, fire and flood effects on macroinvertebrate communities in a catchment with pine and native forest land-use. (#47)

Anthea R Florance 1 , Fiona Dyer 1 , Evan Harrison 1
  1. Institute for Applied Ecology, University of Canberra, Canberra, ACT, Australia

Disturbances such drought, fire and flood are thought to play a significant role in determining the distribution and structure of macroinvertebrate communities. Recovery of macroinvertebrate communities following disturbance has shown to be considerably slower and potentially incomplete in modified landscapes. This is because changes in land-use alter the physical and chemical processes of the landscape, which affects stream characteristics such as habitat and water quality, crucial for the survival of macroinvertebrates. Between the years of 1997 to 2012, severe drought, major fire and a large flood occurred within the Lower Cotter Catchment (LCC) in the ACT. During this period the lower areas of the catchment were managed as a commercial pine forestry plantation estate. The upper areas of the catchment were managed as native forest. Macroinvertebrate data collected from the LCC between 1994 and 2013 was examined to determine the response of macroinvertebrate communities to drought, fire and flood and to determine if land-use affects the recovery of macroinvertebrate communities following fire and flood disturbance. Drought and consequent low stream flows appeared to have an overriding effect on macroinvertebrate community composition. As stream flow decreased during drought the abundance of flow favouring taxa decreased and low flow tolerant taxa increased. Catchment wide fire had less of an effect on macroinvertebrate community composition than flood and land-use did not appear to affect the recovery of macroinvertebrate community composition following fire and flood. This study demonstrates that severe drought has a far greater effect on macroinvertebrate communities than fire and flood disturbance.