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Are bryophytes useful indicators of hydrologic permanence in forested headwater streams?
Citation:
FRITZ, K. M. Are bryophytes useful indicators of hydrologic permanence in forested headwater streams? Presented at North American Benthological Society, Salt Lake City, UT, May 25 - 30, 2008.
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:
Court cases have recently questioned whether all headwater streams, particularly non-perennial streams, should be protected in the U.S. under the Clean Water Act. Rapid field-based indicators of hydrologic permanence are needed for jurisdictional determinations. The study objective was to determine whether bryophytes in forested headwater streams are useful indicators of hydrologic permanence. Bryophytes were sampled from the channel thalweg at 113 sites which varied in hydrologic permanence. Species compositon differed between ephemeral and perennial stream reaches; however, the species composition of intermittent streams overlapped with ephemeral and perennial streams. Three species and six families were identified as indicators of specific permancnce classes. Liverworts occurred more frequently at perennial than at intermittent or ephemeral sites. Bryophytes with cushion and turf growth forms were common at ephemeral sites, whereas mat and weft forms were more common at perennial sites. Species richness was significantly higher at ephemeral than at perennial sites, but neither was significantly different from intermittent sites. Bryophytes should be included among the tools for jurisdictional determinations, much like vascular plants are useful for delineatring wetlands.