Processing and macroinvertebrate colonization of detritus in an Alaskan subarctic stream

• Published in: Ecography
• Main Authors: Cowan, Cathy A., Oswood, Mark W., Buttimore, Carol A., Flanagan, Patrick W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1983
• Subjects: Ecology, Evolution, Behavior and Systematics; Midwinter; Nutt; Subarctic
• Online Access: http://dx.doi.org/10.1111/j.1600-0587.1983.tb01228.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1600-0587.1983.tb01228.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0587.1983.tb01228.x

Monument Creek, a second‐order Alaskan subarctic stream, experiences a severe thermal regime, with water temperatures of 0°C for six months. Leaching, long‐term decomposition and macroinvertebrate colonization of 5 g leaf packs were studied using leaves of the major riparian tree species, alder Alnus tenuifolia Nutt., birch Betula papyrifera Marsh. and willow Salix alaxensis (Anderss.) Cov. subsp. alaxensis and Salix arbucolides Anders. var. glabra Anderss. The processing rates of birch (k = 0.0080) and willow (k = 0.0063) were moderate while alder was processed very rapidly (k = 0.0513). Leaching rates did not differ significantly among the three leaf species, and accounted for 10–15% of total weight loss. Densities and biovolume of colonizing insects increased from fall to winter. Shredders dominated insect biovolume by midwinter, but were a small fraction of total biovolume in leaf packs that had frozen over winter and were sampled following spring thaw. This may be a function of low food quality in spring and/or the timing of shredder life histories. Limited allochthonous input and constriction of the stream channel due to freezing, with resultant high shredder densities, may explain the relatively rapid detritus processing rates in Monument Creek, despite cold stream temperatures.