Publication Title:
Sources and fates of organic inputs in coniferous forest streams
Year:
1974
Status:
Published
Publication Type:
Book Section
H. J. Andrews Publication Number:
1988
Citation:
Sedell, J. R.; Triska, F. J.; Hall, J. D. 1974. Sources and fates of organic inputs in coniferous forest streams. In: Integrated research in the coniferous forest biome. Coniferous For. Biome Bull. 5. Seattle, WA: University of Washington: 57-59.
Abstract:A study of the quality and magnitude of particulate organic inputs wasundertaken in two streams in the Oregon Cascades. Objectives includedestimation of litterfall and lateral movement of organic debris into astream, estimation of litter breakdown rates, and construction of a
first-approximation organic material budget.
In this study, approximately 65% of the litterfall input consisted ofDouglas-fir and hemlock needles, which fall throughout the year. Decid-uous inputs occurred primarily mid-October through November and consistedprincipally of vine maple and bigleaf maple. Preliminary lateral movementdata indicated that organic material entering watershed 10 from the bankwas 1.5 times the litterfall. The total estimate of litter input isapproximately 2.5 g M-2 day-1. Both streams have the capacity to processall types of leaf litter within a year. Needles, the most refractoryleaf litter, are processed by microbes and, once conditioned, are con-
sumed readily by invertebrate shredders. Thus the large amounts ofneedle litter that enter the stream in late summer and fall constitute
a food source usable by stream detritivores after deciduous litter hasdecomposed.
Leaf-pack experiments have revealed the danger of extrapolation of bio-logical information from smaller to larger streams. Faster processingtimes for larger streams have been suggested by information on weightloss, invertebrate biomass, and leaf quality. Changes in litter quality
were determined by increases in the percentage of lignin content. In-creases in lignin composition were compared with decreases in non-cell-wall constituents to obtain an estimate of microbial activity.
Information on litterfall and lateral movement, in conjunction withpreviously collected data, led to a first-approximation particulateorganic matter budget for watershed 10. When compared with a similarbudget from a very different stream system, processing capabilities ofthe two streams were remarkably similar. In both streams almost 990 of
the particulate organic material entered from terrestrial systems. About
two-thirds of the organic inputs entering each stream were processedwithin the system, indicating the processing role of small forest streams.
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