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An assessment of cellulose filters as a standardized material for measuring litter breakdown in headwater streams
Citation:
FRITZ, K. M., S. FULTON, B. R. JOHNSON, C. D. Barton, J. D. Jack, D. A. Word, AND R. A. BURKE. An assessment of cellulose filters as a standardized material for measuring litter breakdown in headwater streams. ECOHYDROLOGY. Wiley Interscience, Malden, MA, 4(3):469-476, (2011).
Impact/Purpose:
Objective: The primary objective of the research is to provide bioassessment programs the scientific tools to study headwater stream ecosystems. In particular these include: 1) standard field protocols for assessing headwater streams (including those that are intermittent); 2) appropriate index periods for field sampling in various geographic regions; 3) physical and biological indicators of hydrologic permanence; and 4) potential stressors or impairments to headwater streams.
Description:
The decay rate of cellulose filters and associated chemical and biological characteristics were compared to those of white oak (Quercus alba) leaves to determine if cellulose filters could be a suitable standardized material for measuring deciduous leaf breakdown in headwater streams. The comparison was done across the reaches draining mixed deciduous forest and post-coal mining catchments, in natural and constructed channels, and ranged in flow duration from ephemeral to perennial. Filter decay rates did not differ across channel type or flow permanence class. Oak leaves decayed ca. 2.5x faster than cellulose filters and there was no relationship between decay rates. Ergosterol concentration, total invertebrate density, shredder density, total invertebrate biomass, and taxa richness were significantly higher in oak litterbags than in filter litterbags. The biomass of invertebrate shredders colonizing litterbags did not differ between the substrate types. The C:N content was higher for filters than for oak leaves, but the mean difference between substrates decreased by ~10-fold over the 306 d study. In contrast, mean differences in ergosterol concentration between substrates increased 3-fold over the study. Although characteristics associated with filter litterbags were related to those of oak leaf litterbags, most relationships had low explanatory power; however, stronger relationships existed for total invertebrate density, shredder density, and taxa richness. Although a standardized material would be useful for incorporating litter breakdown in stream assessments, because of the strong differences in decay rate and associated characteristics we cannot recommend cellulose filters as a suitable substrate to represent the natural breakdown of leaf material.