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FSH 2509.23 -– RIPARIAN AREA HANDBOOK
CHAPTER 3 – DESCRIBING RIPARIAN AREAS
CHAPTER 3 - DESCRIBING RIPARIAN AREAS .............. Error! Bookmark not defined.
3.02 - OBJECTIVE. ......................................................................................................... 1
3.1 - MAJOR MANAGEMENT CONCERNS. .................................................................. 1
3.2 - DESCRIPTION HIERARCHY. ................................................................................ 3
3.21 - National Planning. ........................................................................................................ 3
3.22 - Regional Planning......................................................................................................... 3
3.23 - Forest Planning. ............................................................................................................ 3
3.24 - Project Planning. ........................................................................................................... 3
3.3 - DESCRIPTION COMPONENTS. ................................................................................. 4
3.31 - Vegetation. .................................................................................................................... 4
3.02 - OBJECTIVE.
To delineate meaningful management units, a riparian description should:
1. Address the major management concerns (capabilities, suitabilities, and requirements)
of the riparian resources and uses.
2. Maintain consistency with existing hierarchical classifications of riparian components,
such as soils and vegetation.
3. Use observable traits that are understood and accepted by resource professionals, stable
over time, and easy to recognize.
3.1 - MAJOR MANAGEMENT CONCERNS.
The existence of riparian areas depends on water. Three other resources require riparian areas for
their existence: fish, some wildlife, and some vegetation. Other important uses of riparian areas
on National Forests include timber, grazing, transportation, recreation, mining, and energy.
Understanding the major management concerns of these resources and uses is needed to focus
the riparian description on the most meaningful traits. The following list outlines some major
management concerns of the riparian resources and uses:
1. Water - flood hazards, channel stability, erosion and sedimentation processes, water
quantity and quality.
2. Fish - food, cover, channel structure, water supply and quality.
3. Wildlife - food, cover, water supply, microclimate, migration.
4. Vegetation - diversity of species and size classes.
5. Timber - site productivity, access, pests.
6. Grazing - water supply, forage, microclimate.
7. Transportation - road location and channel crossing potential, flood hazards,
construction materials.
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
8. Recreation.- development potential, aesthetics, micro-climate, flood hazards, fishing
and hunting potential.
9. Mining - mineral deposits, access, water supply.
10. Energy - damsite potential, water supply.
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
3.2 - DESCRIPTION HIERARCHY.
The concept of hierarchy as used in description of riparian areas is based on the fact that more
detailed levels of management require more detailed information on which to base decisions.
This handbook employs such a concept for riparian areas. General principles are discussed
below.
Note use of the term "description" rather than "classification". Some aspects of the description
hierarchy are truly a strict classification (such as vegetation), with other aspects less strictly
defined (such as water permanence). Therefore, the term "description" is more appropriate.
3.21 - National Planning.
National planning requires data on the total area of riparian areas in each Region to define policy
and allocate targets.
3.22 - Regional Planning.
Regional planning requires data on acres of vegetation biomes (formations) within riparian areas
to assess gross productivity, set overall management direction, and disaggregate targets.
3.23 - Forest Planning.
Forest planning requires data to determine broad capabilities and suitabilities for riparian
resources and uses, and to develop prescriptions to achieve desired multiple-use outputs. Define
riparian mapping units (capability areas) using a distinct combination of four characteristics
(vegetation series, valley form, water regime, and water permanence). Aggregate the units into
analysis and management areas based on the major management concerns identified. Constraints
on the total number of mapped areas for the plan require substantial generalization. Sections 3.31
through 3.34 discuss the four characteristics.
3.24 - Project Planning.
Project planning requires data to design site-specific projects within the framework of
established Forest plan prescriptions. The terrestrial ecosystem survey (FSH 2509.14) classifies
land units that integrate vegetation subseries with soil subgroups. These units define land
production potentials at a level sufficiently detailed for project design. Topographic and aquatic
information also help meet the needs of all the riparian resources and uses.
The vegetation subseries used by the terrestrial ecosystem survey for project planning can be
aggregated to refine the vegetation series described here for Forest planning. Until then, consider
the vegetation series shown here as a first approximation. The following table summarizes where
various components enter the riparian description.
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
Planning Level
Component
National
Riparian area
Regional
Vegetation biomes (formations)
Forest
Vegetation biome and series
Valley form
Water regime
Water permanence
Project
Vegetation subseries/soil
subgroups
Detailed topographic/aquatic data
3.3 - DESCRIPTION COMPONENTS.
For Regional planning, describe only vegetation biomes (formations). For Forest planning,
describe the four components: vegetation series, valley form, water regime, and water
permanence. These components were selected because they provide the minimum data needed to
address the major management concerns of the riparian resources and uses. They are also
consistent with existing hierarchical classifications, readily understood and recognized, and
relatively stable over time.
3.31 - Vegetation.
The vegetation components (biomes and series) describe the composition of dominant climax
plants. This handbook classifies only the wet areas (phreatic) communities confined to riparian
ecosystems. For classification of vegetation on the drier upland (vadose) ecosystems see FSH
2509.14.
Vegetation reflects local climate and soil fertility. It therefore implies character of runoff and
erosion, habitat quality for fish and wildlife, and site productivity for timber and forage.
Two existing vegetation classifications are widely used in the Southwest. The theoretical system
of Brown, Lowe, and Pase divides from the top down. The data based terrestrial ecosystem
survey of the Forest Service aggregates from the bottom up, but will not be completed for
phreatic ecosystems for several years. This handbook unites both systems into a single
classification for broadlevel use.
Eleven vegetation biomes are classified for Regional planning. Twenty-four vegetation series
are classified for Forest planning. Exhibit 1 lists these biome and series. Exhibit 2 provides a
brief synopsis of each of these series.
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
Exhibit 1
TYPES OF RIPARIAN VEGETATION
BIOME
CODE BIOME (FORMATION)
SERIES
CODE l/ SERIES
1.
Tundra (Arctic Scrub)
505
Salix arctica
2.
Coniferous Forest (Boreal
Forest)
003
Abies lasiocarpa
3.
Boreal Scrub
314
323
311
Salix glauca
Alnus tenuifolia
Potentilla fruticosa
4.
Coniferous Forest (Cold
Temperate Forest)
001
011
Abies concolor
Picea pungens
5.
Deciduous or Mixed EvergreenDeciduous Forest (Cold
Temperate Forest)
103
Populus angustifolia
6.
Cold Temperate Scrub
335
Salix bebbiana
7.
Deciduous or Mixed EvergreenDeciduous Forest (Warm
Temperate Forest)
130
104
Platanus wrightii
Populus fremontii
8.
Warm Temperate Scrub
350
351
Baccharis glutinosa
Chrysothamnus
nauseosus
Fallugia paradoxa
352
9.
Desert (Subtropical Forest)
131
132
10.
Desert (Subtropical Scrub)
733
734
735
11.
Marshland
415
460
507
Populus
fremontii-Salix
bonplandiana
Prosopis juliflora
Prosopis
juliflora-0lneya
tesota
Hymenoclea spp.
Tamarix chinensis
Deschampsia
caespitosa
Carex nebraskensis
Typha latifolia
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429
423
l/
Sporobolus airioides
Juncus acuminatus
Series codes are consistent with automated timber stand file codes.
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
Exhibit 2
SYNOPSIS OF RIPARIAN VEGETATION SERIES
505 Salix arctica (211.xx) 1/
Wet tundras are of limited geographic distribution and generally undescribed. On wet sites near
late snowbanks in the Wheeler Peak area, Baker (1983) indicates the following dominant or
diagnostic species: Salix arctica, S. reticulata ssp., nivalis, S. glauca, Artemisia scopulorum,
Lloydia serotina, Saxifraga rhomboidea, and Carex nova.
003 Abies lasiocarpa (221.xx)
Abies lasiocarpa (subalpine or corkbark fir) and/or Picea engelmanni dominate the overstory
along streamsides. At lower elevations Populus tremuloides may be an overstory dominant or
codominant along with the conifers, but other deciduous overstory trees are absent. Understory
streamside shrubs include Alnus tenuifolia, Sambucus racemosa, Salix spp., and Cornus
stolonifera. There is a rich and luxuriant assemblage of herbs. Common streamside species
include Cardamine cordifolia, Oxypolis fendleri, Mertensia ciliata, Mitella pentandra, Saxifraga
odontoloma, Senecio triangularis, Circaea alpina, Rudbeckia laciniata, Agrimonia striata, and
Viola nephrophylla.
314 Salix glauca (231.6x)
This is a shrub-dominant, wet meadow vegetation in the higher mountains, mostly above 10,000
feet elevation. The synecology is poorly known, Salix glauca, S. subcoerulea, S. myrtillifolia,
Alnus tenuifolia, and Betula occidentalis may dominate or be codominant in these wet meadows.
323 Alnus tenuifolia (231.6x)
Alder thickets may line streamsides bordering subalpine forests (Abies lasiocarpa series) or blue
spruce forest (Picea pungens series). There are few formal descriptions of alder thickets in the
Southwest, although an Alnus tenuifolia/Salix subseries has been described in the Cuba Ranger
District (terrestrial ecosystem survey 1981).
311 Potentilla fruticosa (231.6x)
A community dominated by shrubby cinque foil can be found in high elevation (mostly above
9500 feet) parklands where cold, wet, organic soils occur. Salix spp., and Alnus spp. are absent.
Common herbaceous species include Poa pratensis, Deschampsia caespitosa, Veratrum
californicum, and Iris missouriensis.
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Exhibit 2 -- Continued
001 Abies concolor (222.xx)
These riparian forests are characterized by overstories of Abies concolor (white fir), Pseudotsuga
menziesii, and Populus tremuloides as dominants or codominants. Some characteristic
subordinate trees or shrubs are Acer grandidentatum, Prunus virginiana, Juglans major, Amorpha
fruticosa, Fraxinus pennsylvanica, Toxicodendron radicans, and Vitis arizonica. Locally,
Pachistima myrsinites may be abundant. There are numerous herbs including Aquilegia
chrysantha, Agrimonia striata, Geum allepicum, Senecio quaerens, Rudbeckia laciniata, Glyceria
spp., Elymus glaucus, Poa palustris, and species of Carex.
Oll Picea pungens (222.xx)
Picea pungens dominates coniferous forests along streamsides that are colder than the Abies
concolor series. Habitat types include the Picea pungens/Poa pratensis and Picea pungens/Cornus
stolonifera forests along streamsides and streamside terraces. Understory shrubs include Salix
bebbiana, Cornus stolonifera, Lonicera involucrata, Ribes spp., and Potentilla fruticosa. A high
diversity of understory herbs includes Rudbeckia laciniata, Heracleum sphondylium, Hypericum
formosum, Veratrum californicum, Sidalcea neomexicana, Mertensia ciliata, Carex foenea, C.
occidentalis, C. festivella, Glyceria spp., Poa pratensis, Calamagrostis canadensis, Scirpus
microcarpus, Geum allepicum, and Viola nephrophylla.
Populus tremuloides is a major seral tree at most locations, but Populus angustifolia is absent or
accidental.
103 Populus angustifolia (222.31, 222.32)
This series includes Populus angustifolia in association w ith Picea pungens, Abies concolor,
Pinus ponderosa, Juniperus scopulorum, or Pinus edulis. There are also mixtures of Populus
angustifolia with Salix spp., as well as with Alnus oblongifolia, Acer negundo, Acer
grandidentatum, and Juglans major. other understory plants include Amorpha fruticosa, Vitis
arizonica, Parthenocissus inserta, Clematis ligusticifolia, Rhus glabra, and Rhamnus betulaefolia.
A rich herb layer includes numerous forbs and such grasses as Elymus glaucus, Poa pratensis,
Agropyron smithii, Sporobolus spp., and Agrostis spp.
335 Salix bebbiana (232.31)
These are streamside willow thickets of boreal forest climates. Trees are either absent or at best
occasional or accidental on special microsites and show no sign of forming a closed forest. Salix
bebbiana, Lonicera involucrata, Ribes spp., Juniperus communis or Sambucus spp., may occur in
the shrub layer. Common riparian herbs include Ranunculus aquatilis, Cicuta douglasii, Senecio
bigelovii, Urtica gracilius, Habenaria saccata, Glyceria spp., Agrostis spp., Carex aquatilis and
other sedges.
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Exhibit 2 -- Continued
Synecological description of these highly diverse willow thickets are absent in Arizona and New
Mexico.
130 Platanus wrightii (223.22)
Platanus wrightii either dominates or is codominant in mixture with other coniferous or
deciduous trees such as Cupressus arizonica, Pinus engelmanni, P. leiophylla, P. ponderosa,
Populus angustifolia, Juglans major, Alnus oblongifolia, Prunus virginiana, Acer negundo,
Fraxinus pennsylvanica var. velutina, or Celtis reticulata. Common vines are Vitis arizonica,
Clematis ligusticifolia, or Parthenocissus inserta. Understory shrubs might include Rhamnus
betulaefolia, Amorpha fruticosa, Toxicodendron radicans, or Rhus glabra. There is usually a
diverse mixture of herbs, among which may be found Pteridium aquilinum, Geranium
caespitosum, Bromus spp., Elymus glaucus, Viola canadensis, Brickellia grandiflora, Stachys
coccinea, Monarda menthaefolia, and many others.
Platanus wrightii galleries occur immediately alongside the cobbly, active stream channels as
well as upon shallow alluvial terraces at short distances from the active channels. Most streams
have perennial flow, but along lower stretches where surface flow is intermittent there appears to
be ample subsurface water.
104 Populus fremontii (223.21)
This is a diverse and geographically widespread series which includes any of the broadleafed
cottonwoods (Populus fremontii, P. deltoidea, P. acuminata). It is the common streamside and
river gallery forest of grasslands (BLP 223.21) and deserts (BLP 224.53). In northern New
Mexico this series reaches its cool, upper elevation limit in the pinyon-juniper lifezone. Here
Populus fremontii may occur with such species as Salix amygdaloides, Salix exigua, Forestiera
neomexicana, Juniperuis scopulorum, J. monosperma, Pinus ponderosa (as in canyons of the
Canadian River), Fallugia paradoxa, Chrysothamnus nauseosus, or Artemisia tridentata (such as,
along the Chama River).
This series has been described in southern Arizona (Tonto National Forest) and southcentral
New Mexico (Mimbres River) by Laurenzi et al., (1983) and Boles and Dick-Peddie (1983).
Associated trees include Populus fremontil, Salix gooddingii, Salix bonplandiana, Fraxinus
pennsylvanica var. velutina, Platanus wrightii, Juglans major, Celtis reticulata, Morus
microphylla, or Acer negundo.
In woodland and steppic climates the soils of this series have been classified as Typic
Ustifluvents, Typic Ustipsamments, and where Salix spp., occur as Aquic Ustifluvents
(terrestrial ecosystem survey 1983b).
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Exhibit 2 -- Continued
350 Baccharis glutinosa (233.21)
This is a poorly known series of open or closed shrub communities along intermittent or
perennial streams generally in steppic climates. Baccharis glutinosa may be associated with
Chilopsis linearis, Fallugia paradoxa, Brickellia spp., Salix spp., or Baccharis sarothroides. These
communities often occur within or bordering the actively scoured channels of streams and
washes. Occasional flash floods may keep these sites free of trees.
351 Chrysothamnus nauseosus (233.xx)
Shrub communities of intermittent washes or actively resorted alluviums of flood discharges are
dominated by Chrysothamnus nauseosus. The common variety is consimilis occurring within,
but not limited to alluvial channels. The series occupies woodland and grassland climates of
perhaps drier or more erratic water or sediment discharge than channels of streams or washes
containing the Baccharis glutinosa series.
Plant communities of the Chrysothamnus nauseosus series have not been widely studied or
described.
352 Fallugia paradoxa (233.2x)
Intermittent streams and dry washes subject to flash floods in deserts, grasslands and woodlands
may be lined with Fallugia paradoxa as the dominant shrub. The communities are poorly known.
Associated plants may be Chilopsis linearis, Anisacanthus thurberi, Sapindus saponaria,
Brickellia laciniata, Rhus microphylla, Ericameria laricifolia, Baccharis sarothrae, Mimosa
biuncifera, Acacia constricta, or Hymenoclea monogyra. Common grasses are Bouteloua
curtipendula, B. gracilis, Leptochloa dubia, and Sporobolus spp. Widely scattered evergreen
Quercus spp., may also be strung out along the wash margins.
131 Populus fremontii-Salix bonplandiana (224.53) (see 104)
132 Prosopis juliflora (Bosques) (224.52)
Mesquite bosques occur along major rivers within the hot desert climates. The diagnostic feature
is the essentially closed stands of tall (over 9 m or 30 feet) Prosopis juliflora var velutina.
Populus spp., or emerqent Salix spp., are absent. Associated plants can include Prosopis
pubescens, Tamarix chinensis, Tessaria sericea, Nicotiana glauca, Phragmites communis (usually
at water's edge), and Cynodon dactylon.
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Exhibit 2 -- Continued
733 Prosopis juliflora-0lneya tesota (234.71)
Ephemeral washes in the Sonoran region exhibit a desert scrub vegetation. Typical species
include Prosopis juliflora, Olneya tesota, Cercidium microphyllum, C. floridum, Baccharis
sarothroides, Chilopsis linearis, Acacia greggii, and Lycium spp. These shrubs along washes
form stringers of higher density and coverage than the more open desert vegetation of adjoining
uplands.
734 Hymenoclea spp. (234.xx)
Hymenoclea monogyra and H. salsola may dominate along broad, sandy washes through deserts.
These are the driest of drainageways capable of supporting riparian obligate plants. Species
associated with Hymenoclea spp., include species of Lycium, Chilopsis linearis, Tessaria sericea,
Prosopis Juliflora, and Baccharis sarothroides. Populus spp., may be encountered infrequently at
great intervals, but the improbability of seedling survival renders the occasional tree as
accidental.
735 Tamarix chinensis (234.72)
Tamarix chinensis forms pure or nearly pure, dense thickets along interrupted or perennial
streams or rivers where subsurface flow is year-long. It is generally believed that these thickets
are derived from Populus fremontii- Salix bonplandiana series and are maintained by fire and
other disturbances as disclimax vegetation.
415 Deschampsia caespitosa (241.7x)
Subalpine marshlands, are characterized by dominance of graminoid mcies rather than shrubs.
With further study these high e evation (above 9500 feet) marshlands or wet meadows might be
subdivided into several series. These plant associations in the Southwest are little studies and
mostly undescribed. Some of the diagnostic plants include Deschampsia caespitosa, Danthonia
intermedia, Calamagrostis canadensis, Hordeum brachyantherum, Juncus arcticus ssp ater, Carex
aquatilis, Carex nebraskensis, Phleum alpinum, Trisetum wolfii, Agrostis spp., and Pedicularis
groenlandica.
460 Carex nebraskensis (242.4x)
This is a poorly known series of montane marshes. Some of the characteristic species include
Carex nebraskensis, Eleocharis spp., Juncus arcticus ssp. ater, Scirpus microcarpa, Calamagrostis
canadensis, Alopecuris aequalis, A. geniculatus, Triglochin maritima, Plantago eriopoda, Aster
hesperus, and Ranunculus hydrocharoides.
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
Exhibit 2 -- Continued
507 Typha latifolia (242.33)
This series embraces Typha latifolia marshes of woodland and steppic climates. Marshes (or
cienegas), seasonal ponds, seeps, or seasonally wet "meadows" may have conspicuous zones of
herbaceous vegetation according to the depth and persistence of water (e.g., the littoral, lower
limnosal, and upper limnosal zones). Some of the commonly encountered plant genera or species
include Sparganium, Potamogeton, Carex, Eleocharis, Juncus, Cyperus, Scirpus, Polygonum,
Paspalum distichum, Echinochloa crusgalli, Rotala ramosior, Mimulus guttatus, and Lemna.
Typha latifolia can form pure stands to the exclusion of many other species.
429 Sporobolis airioides (242.31)
This series includes a variety of little described communities of saline or saline-alkaline soils in
both desert and steppic climates. These grass dominated communities may occur some distance
from a stream or river bottom where lateral subsurface water flow results in capillary water at
rooting depths, but not of sufficient quantity to support woody vegetation. Other sites include
playas and concave drainageways. Some of the typical species are Sporobolus airoides, S.
wrightii, Distichlis stricta, Panicum obtusum, Pucchinellia airoides, and salt tolerant ecotypes of
Agropyron smithii. Saline or alkaline tolerant members of Chenopodiaceae are also found within
this series.
423 Juncus acuminatus (243.5x)
This is a minor series of seasonally flooded, non-saline, non-alkaline soils. Ephemeral ponds or
mudflats may support a mixture of perennial and annual herbs. Climates include deserts,
grasslands, and lower woodlands. Some of the dominant plants are Juncus acuminatus, Rotala
ramosior, Polygonum spp., Eleocharis spp., Echinochloa crusgallii, Eriochloa gracilis,
Leptochloa fascicularis, Myosurus minimus, Veronica peregrina var xalapensis, Panicum
dichotomiflorum, and Xanthium strumarium.
l/ Digitized classification from Brown, Lowe and Pase (1979). The series level classification is
given by two digits to the right of the decimal. Unnamed series are shown by the replacing one
or more digits.
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
3.32 - Valley Form. The valley form component describes the shape of valley cross-sections and
profiles. Determine valley form by valley bottom (toeslope-to-toeslope) width and channel
gradient. Valley form reflects floodplain development and flow energy. It therefore implies
character of floods and erosion, habitat quality for fish and wildlife, and potential for human
activities.
Use three categories to describe valley form: flat, gentle, and steep. Exhibit 1 defines these three
types and shows typical valley cross-sections.
Exhibit 1
TYPES OF VALLEY FORM
Flat (f): valley bottom width exceeds 100 feet or channel gradient is less than three percent.
Gentle (g): either valley bottom width Is less than 100 feet and channel gradient is 3-10 percent,
or valley bottom width exceeds 30 feet and channel gradient exceeds 10 percent.
Steep (s): valley bottom width is less than 30 feet and Channel gradient exceeds 10 percent.
Exhibit 1
SEE THE PAPER COPY OF THE MASTER SET
FOR SECTION 3.32 - EXHIBIT 1
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3.33 - Water Regime. The water regime component describes the type and-size of wate dies.
Water regime reflects amount and influence of surface water. It therefore implies habitat quality
for fish and wildlife and potential for human activities.
Use two categories and six types to describe water regime. Standing water regimes include wet
areas, ponds, and lakes. Flowing water regimes include small streams, medium streams, and
rivers. Exhibit 1 defines these categories and types, and shows diagrams of water regimes.
Exhibit 2 displays channel ordering and channel dimensions in order to help define water regime.
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
Exhibit 1
TYPES OF WATER REGIME
Standing Water: water stands in a topographic depression or an impoundment. Three types are
based on acreage of open water and amount of emergent vegetation.
Wet area (w): surface area is mainly emergent vegetation. Includes swamps, marshes,
bogs, sloughs, wet meadows. seeps, and mud flats.
Pond (p): surface area is mainly open water; annual high water area is less than five
acres (Lehmkuhl and Patton, 1982).
Lake (1): surface area is mainly open water; annual high-water area is five acres or more
(Lehmkuhl and Patton, 1982).
Flowing Water: water flows in a channel. Three types are based on active channel width and
channel order. In a typical active channel is well scoured, lacks perennial vegetation, and has a
definite break in slope at its upper limit. Channel order (Exhibit 1) is determined from
delineated perennial and Intermittent streams shown on 7.5-minute USGS topographic maps.
Small stream (s): active channel width (Exhibit 1 ) is less than 10 feet or channel order is
1 or not shown on the USGS map (Lehmkuhi and Patton, 1982). Includes springs which may
have only few feet of surface flow.
Medium stream (m): active channel width is 10-30 feet and channel order is 2-3
(Lehmkuhl and Patton, 1982).
River (r): active channel width exceeds 30 feet or channel order Is 4 or more (Lehmkuhl
and Patton, 1982).
Exhibit 1
SEE THE PAPER COPY OF THE MASTER SET
FOR SECTION 3.33 - EXHIBIT 1
Exhibit 2
SEE THE PAPER COPY OF THE MASTER SET
R3 AMENDMENT
EFFECTIVE DATE: 02/1985
DURATION: This supplement is effective until superseded or removed
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FOR SECTION 3.33 - EXHIBIT 2
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
3.34 - Water Permanence. The water permanence component describes reliability of surface
water in a water body in time and space. Water permanence reflects water supply for use by
plants, fish, wildlife, livestock, and humans. It therefore implies habitat quality for fish and
wildlife, capability for grazing, and suitability for human uses, such as recreation sites and
hydraulic mines.
Use three categories to describe water permanence: perennial, interrupted, and ephemeral.
Exhibit 1 defines these three types and shows examples.
Forests should describe all four components (vegetation biome and series, valley form, water
regime, water permenence). Each riparian mapping unit will then possess a distinct combination
of characteristics containing one type of each component. Forests may aggregate these mapping
units (capability areas) to build analysis and management areas for Forest plans. The issues,
concerns, and opportunities identified will determine the degree of aggregation warranted.
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EFFECTIVE DATE: 02/1985
DURATION: This supplement is effective until superseded or removed
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
Exhibit 1
TYPES OF WATER PERMANENCE
Perennial (p): surface water is present throughout the year at least 9 years out of 10.
Interrupted (i): surface water alternates between perennial and ephemeral segments. During dry
seasons, water occurs alternately on and below the surface, commonly as perennial pools
separated by dry reaches
Ephemeral (e): surface water is present only seasonally or during runoff events, and is normally
not present during dry seasons.
Exhibit 1
SEE THE PAPER COPY OF THE MASTER SET
FOR SECTION 3.34 - EXHIBIT 1
R3 AMENDMENT
EFFECTIVE DATE: 02/1985
DURATION: This supplement is effective until superseded or removed
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CHAPTER 3 – DESCRIBING RIPARIAN AREAS
3.4 - IMPLICATIONS. The vegetation biome and series, valley form, water regime, and water
permanence components were selected because they best address the major management
concerns of the riparian resources and uses. This section presents some implications of the
description of riparian areas to these management concerns. Understanding these implications
explains the use of the four components and identifies tradeoffs that should be assessed when
planning the management of riparian areas.
3.41 - Flood Hazards. Precipitation and cover conditions in source-area watersheds influence
flood characteristics. Floods in arctic, boreal, and cold temperate biomes result mostly from
snowmelt. The typically dense ground cover promotes infiltration and subsurface delivery to
channels. Floods in warm temperate and subtropical biomes result mostly from thunderstorm
runoff. The typically limited ground cover promotes overland flow and flash floods.
Channel and floodplain characteristics also help determine flood hazards. Flood volumes and
flooded areas are greatest along rivers in flat valleys. Flat valleys contain most of the significant
floodplains evaluated in Forest plans and land exchanges (FSM 2527). Flash floods caused by
thunderstorms are most damaging along small streams in steep valleys.
3.42 - Erosion Processes and Channel Stability. Ground cover influences soil erosion and
sediment loads. Hot and dry ecosystems limit plant growth and ground cover. The highest
hazards of accelerated surface and gully erosion, with subsequent sediment impacts to
downstream riparian areas, occur in subtropical and warm temperate biomes.
Channel gradient and flow stability influence channel processes. Streamflows typically range
from slow and meandering in flat valleys to rapid and straight in steep valleys. The key fluvial
processes include channel bank erosion and floodplain deposition in flat valleys, sediment
transport in gentle valleys, and channel bed and sideslope erosion in steep valleys. Ephemeral
channels commonly remain unstable because their rare flows cannot transport the typically high
sediment loads they receive.
3.43 - Water Supply and Quality. The abundance and persistence of surface water increase with
precipitation, infiltration, and subsurface water concentration. The majority of perennial water
bodies, therefore, occur in arctic, boreal, and cold temperate biomes. Dependability of water
supply ranges from high in perennial water bodies to low in ephemeral water bodies.
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Shade, ambient air temperature, and ground water inflow volumes and temperatures influence
surface water temperatures. Ground cover influences sediment loads. Surface waters, therefore,
remain typically cooler and clearer in arctic, boreal, and cold temperate biomes. Most coldwater fisheries occur in these biomes while warm-water fisheries prevail in subtropical and warm
temperate biomes.
3.44 - Aquatic Food and Channel Structure. Exposure to sunlight infuences the aquatic food
chain. The food base consists mostly of detritus in small forest streams and plankton in exposed
rivers.
The action of streamflow forces on the channel bed and banks influences channel structure.
Large woody debris and channel meanders concentrate streamflow forces to increase pool-riffle
ratios, pool depths, and overhanging banks. The productivity and diversity of aquatic habitats
are, therefore, typically highest in forest biomes and flat valleys. Channels in steep valleys
generally provide marginal aquatic habitat. Perennial streams exhibit more productive habitat
because their more dependable flows sort sediments more efficiently and create better pools and
riffles.
3.45 - Plant Growth and Diversity. Availability of moisture infuences plant vigor and diversity.
With moisture seldom limiting in riparian ecosystems, high potential exists for vigorous and
diverse plant growth. Wet areas produce more biomass than any other ecosystem and contain
prime habitats for many wildlife species, especially in warmer biomes where temperatures pose
no limits. Highest diversity of wildlife habitat exists in forest biomes with numerous edges and
strata. Some wildlife species require certain vegetation series as their prime habitat.
Soil properties also influence plant vigor and diversity. The well-developed floodplains along
rivers in flat valleys typically contain the deepest and most fertile soils in the landscape.
Enriched nutrients and moisture produce a high potential for vigorous declines and diverse as
valleys than on upland slopes plant growth. This potential generally steepen, but remains higher
in steep valleys.
3.46 - Engineering Uses. Slope and soil moisture influence suitability for road location with
suitabilities generally high in flat valleys but low in wet areas. Suitability for recreation sites
depends on slope, soil moisture, and amount of open water. Recreation sites are, therefore, most
suitable in flat valleys along perennial water bodies. Small streams are most suitable for channel
crossings.
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Suitability for dams often depends on amount of inflow and reservoir area, versus width of dam.
Dams are, therefore, most suitable across perennial rivers in narrow sections of flat valleys.
Placer deposits are most common in the deep alluvium of flat valleys.
3.47 - Recreation Uses. Riparian characteristics commonly influence suitability for certain
recreation activities. For example, fly fishing requires more open, cool, gentle pool/riffle stream
qualities. Dense cover along small streams often mandates other fishing techniques. High volume
steep gradient whitewater is suitable for rafting and kayaking. Streams cascading over bedrock
attract landscape photography and swimming. Water temperature influences the target species
for various fishing enthusiasts. Visual variety and contrasts in stream characteristics influence
the landscape viewing attractiveness for photographers, campers and picnickers.