Long-term impacts of wildfire on macroinvertebrate community structure in an arid-land stream

Authors: Nathan Dorff, Michael Bogan

Year: 2017 (xlix)

Abstract

Wildfires are natural disturbances that shape terrestrial landscapes and can alter aquatic ecosystems Wildfires followed by heavy rain cause debris flows and scouring, potentially compounding effects on aquatic systems In 2011, the Horseshoe 2 Fire burned over 90,000 hectares in southeast Arizona and was followed by heavy monsoonal rains and subsequent flooding and scouring We monitored the aquatic macroinvertebrate community at one affected stream, East Turkey Creek, for four years pre-fire and six years post-fire Taxonomic richness was significantly reduced post-fire, while overall abundances of macroinvertebrates remained the same We observed post-fire increases in relative abundances of certain r-strategist taxa The most common pre-fire taxa (baetid mayflies and blackflies) remained common post-fire, while other taxa saw sharp declines in densities for at least 5 years post-fire We also found that some taxa (eg glossosomatid caddisflies) experienced large increases in densities post-fire, as documented in other studies We used non-metric multidimensional analysis to track community composition pre- and post-fire, and found that recovery to pre-fire community composition took around 4 years With hotter and drier conditions predicted in the arid Southwest, more frequent and higher severity fires will occur It is important to understand how these novel fire regimes will alter aquatic systems