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We investigated the influence of the mountain pine beetle infestation and salvage harvesting on small stream and riparian zone ecological function, shade, and temperature. Small streams (less than a 2 m bankfull width) were selected because they are the most prominent stream type within a watershed and they determine many ecological characteristics of larger downstream channels. Due to their prominence, they are also the most frequently encountered channel type during forest-harvesting activities, and they have no legislated riparian reserve zones. Riparian areas within the pine-dominated watersheds studied here were primarily comprised of spruce, whereas upland areas were comprised of pine. Field assessment of 39 small streams (n = 19 control and 20 treatment) indicated that grey attack channel reaches had properly functioning riparian areas and streams, whereas salvage-harvested areas were functioning with some level of impairment. Shade levels were significantly lower in harvested areas, which allowed greater light penetration compared to the higher-shade mountain pine beetle-affected streams. Air temperature was also significantly higher above streams with salvage-harvested riparian zones. Stream temperature, in contrast, showed a variable response. Small streams of groundwater origins did not exhibit significant differences in warming trends between control and treatment reaches. Small streams with surface-water origins, such as those from lakes and wetlands, exhibited a significant decrease in cooling in harvested reaches compared to their control reaches.
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