Comparative effects of wildfire and timber harvest on periphyton and zoobenthos in two northern Rocky Mountain streams
Year: 1991
Type: dissertation
Abstract: Disturbance of terrestrial habitats within small watersheds may result in significant changes in stream community structure and function.Two common disturbance types in small northern Rocky Mountain watersheds resulting in deforestation are naturally occurring wildfires and man's timber harvests.This study exEunined the comparative role of a 20 year old logged reach and a recently burned (<1 year old) portion of a catchment basin on the periphyton and zoobenthic assemblages in two northwest Montana streams.Artificial substrates, placed in the streams, were periodically sampled over a 16 week period to determine chlorophyll a biomass, AFDM, and algal taxa of the periphyton community.Biofilm accumulation was significantly higher on tile surfaces in disturbed stream reaches compared to undisturbed reference reaches.Periphyton growth was significantly higher at the logged site compared to the unlogged site, apparently due to higher light intensities at the open canopy, logged site.Similarly, periphyton growth appeared to be stimulated in the fire impacted reach compared to the unbumed reference reach, but only at the end of the 4 month experiment.This increased periphyton growth was apparently due to higher light intensity and nutrient concentrations in the burned reach.The delayed algal growth response in the recently burned reach may have been due to the lack of high light intensity adapted algal taxa during the initial colonization period.Zoobenthos density was not significantly different between logged and unlogged sites possibly because the logged site was an old disturbance event with a significantly higher predator density than the unlogged site.Zoobenthos density at the burned site was significantly higher compared to the unbumed site probably due to the higher nutrient concentrations and higher light intensity in the burned reach that resulted in greater algal growth.
Source: The Mathematics Enthusiast
Author: John Thomas. Gangemi
Institution: University of Montana
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W2470033803