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Communication at the NABS Annual meeting, Keystone, 2000
(251) SEASONAL AND SPECIES-SPECIFIC VARIATIONS IN THE DECOMPOSITION RATES OF
PARTICULATE AND DISSOLVED ORGANIC MATTER.
J.S. Richardson, C. Shaughnessy, and M.D. McArthur. Department of Forest Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
Streams receive a variety of litter inputs and the types are strongly
influenced by land-use activities, such as forestry, which convert the
vegetation composition of entire watersheds. We studied decomposition
rates of three common species of leaf litter in small, coastal rainforest
streams. Loss rates of CPOM of red alder, western redcedar, and western
hemlock, were determined in two seasons. In summer and fall alder lost
mass more quickly (k = -0.024, -0.008) than the two conifer species.
During summer hemlock lost mass significantly faster than cedar (k = -0.017
versus -0.013), but this was reversed in autumn (k = -0.004 versus -0.005).
Microbial use of DOC from each source (based on a leucine uptake assay)
showed that alder was the highest quality source of DOC (2.8 µg
Cbacteria/h/cm2/mg DOC), with cedar slightly lower
(2.2). Hemlock was a very poor source of DOC, resulting in bacteria growth
rates of only 0.19. Conversion of riparian vegetation changes quality of
organic inputs, but may affect timing of resource availability.
Presented at 9:45 AM on Thursday, June 1, 2000 in Organic Matter Processing I
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