|Forest Investment Account|
|Abstract of FIA Project Y051367|
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Effects of logging on export of organic matter from headwater streams
|Author(s): Heise, Brian A.||Imprint: Kamploops, B.C. : Thompson Rivers University, 2005||Subject: Forest Investment Account (FIA), Streams, British Columbia||Series: Forest Investment Account (FIA) - Forest Science Program|
We have quantified the mean export of aquatic invertebrates, mean export of fine particulate matter (FPOM), and the range of dissolved organic carbon (DOC) export from headwater streams in two study areas representing two subzones of the Englemann Spruce - Subalpine Fir biogeoclimatic zone in British Columbia’s southern interior. Thirty high elevation (1091 m - 1892 m) streams were selected for sampling at Bone Creek and Damfino Creek and categorized into three treatment types: new clearcuts logged since 2001, old clearcuts logged since 1997, and undisturbed controls. Paired sites were sampled on each stream, located above and within clearcuts at a fixed distance apart, and positioned at the same fixed distance apart at control streams. Discharge rates at all sites ranged from 4.08 E-07 to 2.38 E-02 m3 sec-1, FPOM concentrations ranged from 0.37 to 5.0 mg/L, and drift ranged from 2.37 to 79.50 individuals m-3. By comparing differences between paired lower and upper sites among the three treatments and between combined clearcuts and control streams, we found differences at one or both study areas in FPOM export, total invertebrate abundance, Ephemeroptera abundance, abundance of two Ephemeroptera families, EPT/D biotic index, EPT taxa richness, proportion and diversity of clinger taxa, and functional feeding group representation. Paired site differences for overall invertebrate abundance were significantly higher in both new and old clearcuts compared with controls at Damfino Creek (p=0.015, 0.024). At Bone Creek, paired site differences for overall invertebrate abundance was significantly higher in combined clearcut streams compared with controls (p=0.048). Paired site differences for abundance of Ephemeroptera was significantly higher in old clearcut streams compared with controls at both Bone Creek and Damfino Creek study areas (p=0.047, 0.048). Paired site differences for overall invertebrate drift biomass did not differ among treatments in either study area (p=0.529, 0.405). Two biotic indices calculated from biomass differed at Bone Creek. Mean paired site differences for the proportion of clingers was higher at control compared with old clearcut streams (p=0.048), and for EPT/D was significantly different among treatments (p=0.036). Mean paired site differences at Damfino Creek for clinger taxa diversity differed among treatments (p=0.048), and for EPT richness was significantly higher in new clearcut streams compared with controls (p=0.043). Paired site differences for the proportion of predators was significantly higher in new clearcut compared to old clearcut streams at Bone Creek (p=0.045), while at Damfino the opposite trend was significant (p=0.034). Clearcut logging at Bone Creek and Damfino Clearcut has increased the total abundance of drifting invertebrates and has not changed the biomass of invertebrate export. The results of this study show that biomass has not changed at either study area and therefore logging appears to have a variable effect on overall invertebrate export. These data can assist in implementation of the results-based Forest Practices Code in BC, as they can show the response of the invertebrate community to forest harvesting.
Updated September 08, 2005
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