Streams

Stream Reach Characterization

Background:

In our previous work, we found that approximately equal portions of variance in physical variables important to stream biota could be attributed to surficial geology and other measures of landscape structure (Richards et al. 1996). However, distinct differences were observed in the relative influence of geologic versus land use factors on certain parameters. For example, variation in bankfull width was primarily explained by geologic factors, whereas woody debris was influenced much more by land use. Other factors, such as flood intensity, were equally influenced by land use and geologic factors. Further analyses revealed that watershed size, extent of rowcrop agriculture, and contrasts in dominant surficial geology within watersheds were the most important regional features influencing stream habitats and biota (Richards et al. 1996).

Methods:

Because physical habitat is important to all of the biotic variables quantified in this project, we are measuring a comprehensive set of parameters at each site (Table). These parameters are commonly measured in stream surveys (Osborne et al. 1991). At each site, a stream reach of approximately 200 m will be designated; this is usually sufficient to incorporate more than one riffle-pool sequence (Richards 1982, Bisson and Montgomery 1996).

Table: Endpoints and methods for physical habitat determination.

Category	Parameter	Methods
Bank and Riparian Conditions	upper and lower bank stability, streamside cover, riparian zone	Osborne et al. 1991, Plafkin et al. 1989
Channel Morphology	channel alteration, bottom scouring, deposition, pool/riffle ratio, sinuosity, gradient	Plafkin et al. 1989, Osborne et al. 1991, Platts et al. 1983, Armour et al. 1983
In-stream	substrate composition, % fines, % embeddedness, velocity depth, shading, width, temperature	Plafkin et al. 1989, Platts et al. 1983, Armour et al. 1983, Osborne et al. 1991

Deployment of woody debris in streams