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Effects of a forest fire upon the benthic community of a mountain stream in northeast Idaho

Author(s): Deborah Cynthia Stefan
Year Published: 1977

The purpose of this study which was conducted in 1974 and 1975 was to investigate the effects of the Fitz Creek fire of August, 1973 upon the benthic community of White Cap Creek which was partially surrounded by the bum. Study sections of White Cap Creek within the burn, below the burn, and above the burn were examined. Taxonomic composition, distribution, density, and relative abundance of benthic invertebrates were compared within and between stream study sections. Effects of the fire upon insect drift, periphyton, detritus, and physical parameters of the stream were also investigated. There were neither sudden nor drastic changes in species composition of benthic invertebrates with the exception of Plecoptera between the burned and unburned stream areas. The uppermost station of the burn area was more similar in relative abundance of macro-invertebrates to stations above the burn than to its more proximal station within the burn. However, there was a sharp contrast in relative abundance of Coleoptera between stations above the burn and all other sites. Plecoptera was the only taxa for which significant differences in numbers in artificial substrates among study sections occurred, whereas significant differences in numbers of four taxa occurred within study sections of White Cap Creek. Diel periodicity and total numbers of subsurface drifting organisms were similar between the burn and below-burn stations. There was a marked increase from 1974 to 1975 in numbers of surface drifting organisms at both burn and below-burn stations. Percentage composition of total drift was similar between stations with surface drift comprising a large percentage of total drift. The above-burn sampling site which was adjacent to the burn had substantially higher amounts of chlorophyll on periphyton samplers than other sites. Slightly higher amounts of chlorophyll on periphyton samplers occurred at the uppermost station above the burn as compared to the burn and below-burn areas. There were no significant differences among study sections in the amounts of detritus accumulated in stations. However, there was a significant difference in the amounts of fine detritus accumulated within above-burn stations. Water temperatures were 0.5° to 1.5° C. higher within the burn as compared to the above-burn area in 1974 and 1975. The fire appeared to have little overall effect on the benthic community of White Cap Creek.

Citation: Stefan DC. 1977. Effects of a forest fire upon the benthic community of a mountain stream in northeast Idaho. University of Montana Master' Thesis. 6924. https://scholarworks.umt.edu/etd/6924
Topic(s): Fire Effects, Ecological - Second Order, Water, Wildlife, Fire & Wildlife, Invertebrates, Aquatic
Ecosystem(s): None
Document Type: Dissertation or Thesis
NRFSN number: 18664
Record updated: Dec 3, 2018