Lignin and cellulose content of benthic fine particulate matter (FPOM) in Oregon Cascade Mountain streams.

Compared to leaf litter, benthic fine particulate organic matter (FPOM) is consideredvery refractory. FPOM exhibits high carbon to nitrogen ratios, low respiratory rates, and is arelatively poor food source for invertebrates. However, little more is known of the qualitativenature of benthic FPOM, the nature of FPOM processing, or the relationship between benthicFPOM chemical composition and sources of organic matter to a stream system. In this study,qualitative characteristics of benthic FPOM were compared at three sites in the Oregon CascadeMountains that received either conifer litter, alder leaves, or herbaceous and algal inputs. FPOMfrom these streams contained approximately 45% lignin and 10-15% cellulose (ash-free dry weight).Lignin content of particles >1 mm was almost 60% whereas in those Key words: lignin, cellulose, FPOM, benthos, Oregon, detritus, respiration, ecosystem stability.