8097

• UCREFRP Catalog Number: 8097
• Author: American Fisheries Society.
• Title: Proceedings of the 18th Annual Meeting, Colorado - Wyoming Chapter, American Fisheries Society.
• USFW Year: 1983.
• USFW - Doc Type: March 2-3, 1983.
• Copyright Material: NO

The major objective of this study was determination of the trends
and responses of riparian plant communities, along Rock Creek in the uinta
Mountains of Utah, to the different combinations of 1) soil moisture and
salinity, 2) solar irradiation as affected by adjacent mountains, and 3)
stream action. In addition, unique features of the stream hydrology and
riparian vegetation along the Lake Fork and Yellowstone Rivers must be
considered to clarify relations between the vegetation and physical factors
of the environment along Rock Creek.
The annual discharge of Rock Creek is approximately 115,700,984 cubic
meters, and it drains a watershed of approximately 622 square kilometers
(240 square miles). Spring runoff contributes most of this water during
the months of May and June, with average daily flows ranging from 17.0
to 22 cubic meters per second. Stream flows during the remainder of the
year are generally below three cubic meters per second. Elevations of
the stream segments studied ranged from 1,830 meters (6000 feet) to 2,430
meters (8000 feet). Average annual precipitation for these segments ranged
from 25 cm (10 in.) to 75 cm (30 in.). Lowest precipitation occurred during
the months of March and April and greatest precipitation occurred during
August and September.

METHODS

A detailed description of methods used is presented elsewhere (Hansen,
1977). Only a brief description is provided here.
Field research was conducted during the summers of 1975 and 1976.
Vegetative parameters such as c~ver, production, and density were measured
for2species in each of five 5 m plots (shrub and tree strata) and ten
1 m plots (herb strata) in each of 71 vegetative communities adjacent
to Rock Creek. Other parameters measured were temperature, relative
humidity, plant water potential, distance above and to the stream, and
soil depth or stoniness as assessed by 1 m x 1 cm metal rod pushed as far
as possible into the ground. Soil samples were analyzed for bulk density,
soil moisture, pH, electrical conductivity, and texture.
Computer and statistical analyses were performed using MIDAS programs
at the University of Michigan. The types of analyses included: cluster
analyses, one-way analysis of variance, stepwise multiple regression
analysis, discriminant analysis, principal component analysis and other
descriptive statistics.

RESULTS

Cluster analysis based on importance values (canopy cover and relative
abundance) resulted in the selection of eight major groupings of riparian
communities. Names were assigned to these groupings based on the dominant
species (species with the highest average importance value): alder, willow,
birch, conifer, cottonwood, aspen, hawthorn, and buffaloberry. Cluster
analysis of the herb strata, based on importance values of presence and
absence of a species, resulted in selection of different groups. This
suggests that understory species are not restricted to a particular overstory
species, but may be distributed according to similar environmental conditions,
particularly soil moisture. For example, 1) the birch, alder, and willow;

61