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Riparian Community Type Classification 1
in the Intermountain Region
Andrew P. Youngblood, Wayne G. Padgett, and Alma H. Winward
2
Abstract.--Classification of riparian ecosystems in
Idaho, Wyoming, and Utah into different community types,
based upon similarities in floristic composition, provides
a tool for resource management. Diagnostic keys that utilize
conspicuous plant species provide for field identification.
Environmental relationships, successional status, and
management implications are discussed.
INTRODUCTION
classification include:
!--contribution to a broad Intermountain
Region ecosystem classification effort;
2--description of characteristic geographic,
topographic, edaphic, and floristic
features of each type;
3--description of probably successional
trends for each type; and
4--description of resource values and
management opportunities for each type~
Riparian ecosystems in the mountainous
portions of Idaho, Wyoming, and Utah often form
relatively narrow transition zones between
aquatic and terrestrial ecosystems. These
riparian zones have often been overlooked, or
considered minor inclusions of the larger
terrestrial systems. Current National Forest
policy requires the recognition of the unique
values of riparian ecosystems, and emphasizes
their protection, management, and improvement
during the planning and implementation of land
and resource management activities (Peterson
1983). Classification of the riparian ecosystem
provides the resource manager a means of
inventory and delineation and a tool for refining
management.
METHODS
Riparian communities are composed of plant
species that require or tolerate free or unbound
water. They are identified by a combination of
soil characteristics and distinctive plant
species composition that usually differ from
upland plant communities. Communities for
sampling were selected to reflect the apparent
range of environmental and successional
conditions of an area and the relative
homogeneity of vegetation. Sample plots (SO m2
in size) in riparian communities were established
to avoid ecotones.
The Ecology Program of the Intermountain
Region, USDA Forest Service, initiated fieldwork
in 1979 leading to the development of riparian
ecosystem classifications. Classifications in
progress or already completed include portions of
the Boise and Payette (Mutz and Queiroz 1983),
Challis and Sawtooth (Tuhy and Jensen 1982),
Targhee, Bridger-Teton, and Caribou (Youngblood
and others, in press), and Wasatch-Cache, Uinta,
and Ashley National Forests (Youngblood and
others, in prep.).
Data from sample plots included:
-canopy coverage of all vascular plant
species, ocularly estimated;
-herbaceous standing crop (annual
production);
-soil profile description for top meter;
-bedrock and geology;
-aspect, slope, relative position, and
elevation;
-relationship to adjacent riparian and
upland communities; and
-recent disturbances and successional
relationships.
The objectives of riparian ecosystem
1
Paper presented at the first North American
riparian conference, Riparian Ecosystems and
their Management: Reconciling Conflicting Uses.
[Tucs~n, Arizona, April 16-18, 1985].
Andrew P. Youngblood is Area Ecologist and
Wayne G. Padgett is Range Conservationist for the
USDA Forest Service, Intermountain Region,
stationed at the Forestry Sciences Laboratory,
Logan, Utah; Alma H. Winward is Regional
Ecologist for the Intermountain Region, stationed
at Ogden, Utah.
Within the last 6 years, over 1000 plots
have been sampled in riparian communities in the
mountainous portions of central and eastern
Idaho, western Wyoming, and northern Utah.
Fieldwork generally followed procedures developed
510
by Norton and others (1981) and refined by Tuhy
and Jensen (1982).
The overall goal of this classification
effort was to develop types that are meaningful
and useful to the resource manager who may be
concerned with management practices and their
consequences within the riparian ecosystem.
Perhaps the most significant aspect of this work
is its delineation of the riparian ecosystems
within the mountainous portions of the
Intermountain Region. Resource managers now have
a tool for identifying, in a field situation, the
existence or boundaries of the riparian zone and
the ecotone between it and terrestrial
communities.
Data analysis was designed to assist in the
development of an efficient natural taxonomic
classification of riparian communities. All
field data were computer coded for vegetation and
environmental analysis. Preliminary association
tables (Mueller-Dombois and Ellenberg 1974) were
created, using plot species and canopy coverage
values. Tables were rearranged to group sample
plots with floristic similarities. Cluster
analysis, using the Bray-Curtis similarity
coefficient (Romesburg and Marshall 1984)
provided a somewhat objective mathematical
grouping of sample plots, arranged as a
dendrogram. Detrended correspondence analysis
(Hill and Gauch 1980) is an ordination technique,
and was used to derive inferences of
relationships between sample plots and
environmental gradients.
Furthermore, the resource manager now has a
tool for describing ripariart resources and
communicating concepts relating to riparian
community types for a variety of users through a
single common classification. The riparian
community type classifications portray the
diversity of communities, successional patterns,
and site characteristics within the study areas;
they provide a basis for continuing studies of
successional relationships; and they provide an
inventory of major plant species and insights
into relative amplitudes of common riparian
species. The riparian classifications provide a
tool for refining grazing systems based on
sensitivity of plant species and site-selection
by livestock; they are being used to stratify
wildlife habitat and determine wildlife habitat
values; and they provide a framework for the study
of streambank stability and fish habitat.
Different community types may bP. used to refine
prescribed fire plans. Finally, the
classifications provide a framework for
developing silvicultural prescriptions for
various objectives.
RESULTS AND DISCUSSION
The results of the different data analysis
techniques were combined to form final
classification of sample plots. Groups represent
riparian community types, which are defined as
units of vegetation having similar floristic
composition, regardless of successful status.
Within the Intermountain Region, about 70
community types have been classified and
described. Community types were named after the
dominant overstory and dominant or most
diagnostic undergrowth species. Thus, a
community characterized by Salix wolfii in the
overstory, and an undergrowth consisting of Carex
aquatilis and various mosses, is identified and
written as belonging to the SALIX WOLFII/CAREX
AQUATILIS community type. Field identification
of the community type is made through the use of
dichotomous keys.
LITERATURE CITED
Hill, M. 0., and H. G. Gauch, Jr. 1980.
Detrended correspondence analysis: an
improved ordination technique. Vegetatio
42:47-58.
Mueller-Dombois, D., and H. Ellenberg. 1974.
Aims and methods of vegetation ecology. 547
p. John Wiley and Sons, New York.
Mutz, K. M.; and J. Queiroz. 1983. Riparian
community classification for the Centennial
Mountains and South Fork Salmon River,
Idaho. 170 p. Contract No. 53-84
MB-2-0048, Meiiji Resource Consultants,
Layton, Utah. Unpublished.
Norton, B. E., J. Tuhy, and S. Jensen. 1981.
Riparian community classification for the
Greys River, Wyoming. 188 p. Department
of Range Science, Utah State University,
Logan, Utah. Unpublished.
Peterson, R. M. 1983. Riparian management on
the National Forest System. Fisheries
8:22-25.
Romesburg, H. C., and K. Marshall. 1984. User's
manual for CLUSTAR/CLUSTID computer programs
for hierarchical cluster analysis. 89 p.
Lifetime Learning Publs., Belmont, Calif.
Final published reports for each different
geographic area within the Intermountain Region,
such as South Fork Salmon River, included keys,
distribution maps, and complete community type
descriptions. Type descriptions indicated
characteristic vegetation, general soils features
and taxonomy, successional status, and pertinent
physical and environmental features. When
possible, preliminary management implications
were discussed.
Community type classifications are
hierarchical in that community types may be
aggregated upward into larger dominance groups
which share common physiognomy or overstory
composition. This level of stratification may be
useful for broad regional planning. Within the
Intermountain Region, our dominance groups were
named after forest tree species, such as Populus
angustifolia, Betula occidentalis, or Picea
engelmannii; tall shrubs, such as Alnus incana,
Cornus stolonifera, Salix geyeriana, or Salix
boothii; low shrubs, such as Salix wolfii,
Potentilla fruticosa, or Arte~ cana; or
herbaceous species, such as Carex rostrata,
Deschampsia cespitosa, or Ve~m californicum.
511
Tuhy, J. S., and S. Jensen. 1982. Riparian
classification for the Upper Salmon/Middle
Fork Salmon Rivers, Idaho. 200 p. White
Horse Associates, Smithfield, Utah.
Unpublished.
Youngblood. A. P., W. G. Padgett, and A. H.
Winward. In press. Riparian community
type classification of eastern Idaho-western
Wyoming. USDA Forest Service R-4-Ecol-85-1.
Intermountain Region, Ogden, Utah.
Youngblood, A. P., W. G. Padgett, and A. H.
Winward. In prep. Riparian community type
classification of northern Utah. USDA
Forest Service, Intermountain Region, Ogden,
Utah.
512