Common (Translated Scientific) Name: Greasewood - Iodinebush - Chairmaker's Bulrush North American Interior Brackish Marsh, Playa & Shrubland Division
Colloquial Name: North American Western Interior Brackish Marsh, Playa & Shrubland
Hierarchy Level: Division
Type Concept: This division covers non-tidal interior saline-alkaline wetlands, salt flats, lower basins, marshes and seeps that occur throughout much of interior temperate to subtropical North America from Oregon, eastern Washington, and southern British Columbia across the intermountain basins, eastward through the Great Plains and from southern and central California and adjacent Baja California, Mexico, through the warm deserts of North America to Texas. Stands may occur near drainages on stream terraces and flats or may form rings around more sparsely vegetated playas. They may also occur at the interior edge of coastal salt marshes along the southwestern portion of the Pacific Coast where relatively low rainfall and high evaporation tends to concentrate salts near the surface. In general, key taxa are divided into two groups: halophytes of substrates with higher salt concentrations and salt-tolerant marsh plants. Halophytes include various woody and herbaceous members of the Chenopodiaceae which either store water in stems or leaves or exude excess salt from glands on leaves, and also include some members of the Asteraceae such as the Isocoma acradenia-Isocoma arguta-Isocoma rusbyi complex. The brackish marsh key species Schoenoplectus americanus is an excellent disperser and is regularly found in most stands throughout the range of the division. Allenrolfea occidentalis is a strong diagnostic species covering the southwestern portion of the extent of the division. It overlaps with Sarcobatus vermiculatus, which covers the northern and western portion of the division's distribution.
The climate of most stands is characterized by long periods of drought during the summer months. Maximum or minimum temperatures range widely from well over 45°C to well below 0°C. Coastal fringes of the desert or semi-desert in southern California south to central Baja California, Mexico, have mild temperatures, but may have very high evaporation. Many of the key species of shrubs or wetland herbs have broad distributions and have broad temperature tolerance. Salinity ranges from brackish to hypersaline. Texture ranges from peat and muck in perennial wetlands to heavy clay soils in and around playas or uplifted sea or lake beds in interior basins and valleys. Most soils are fine-textured and many have mineral crusts. Hydrology varies from permanent stream and spring flow to highly episodic flooding along desert streams and playa basins. Many stands of halophytic shrubs have fluctuating saline water tables.
Diagnostic Characteristics: Key species are restricted to non-tidal, salt-tolerant shrublands or herbaceous wetlands of permanent brackish marshes, seasonally or intermittently wet playas, lake margins, and closed basins. This division contains several related taxa, which taken together taxonomically are key taxa being largely restricted, widespread, and often dominant. These include the Schoenoplectus americanus - Schoenoplectus pungens complex, Sarcobatus vermiculatus - Sarcobatus baileyi complex, Suaeda calceoliformis - Suaeda moquinii complex, and the Salicornia rubra-Salicornia depressa complex. Distichlis spicata, although common and ubiquitous, is a moderate diagnostic because it occurs in a number of divisions.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Distinction between this division and the Great Plains saline marshes needs careful review. Non-coastal and non-tidal salt marshes and shrublands become alkaline to saline by evapotranspiration strongly exceeding precipitation. The classification concept of this division emphasizes the broad adaptations of halophytic vegetation to variations in salinity and in moisture availability. Most of the diagnostic species of this division are widespread halophytes in North America and may actually be treated more broadly to include a circumboreal or hemispheric distribution (e.g., as is suggested for some species of Eleocharis, Salicornia, Schoenoplectus, etc. in Flora of North America (FNA Editorial Committee 2002b).
Similar NVC Types:
D035 Temperate & Boreal Pacific Coastal Salt Marsh, note: includes coastal and tidal estuaries. These divisions blur in central and south coastal California southward into Mexico where the lower annual precipitation and higher evaporation rates of upper coastal salt marshes tend to foster conditions appropriate for interior salt marsh vegetation.
D040 Western North American Cool Semi-Desert Scrub & Grassland, note:
D033 North American Great Plains Saline Marsh, note: There are potentially strong enough overlaps in composition to make the distinction between these two divisions very problematic.
Physiognomy and Structure: Stands are variable depending upon degree of perennial to seasonal saturation or flooding, and degree of salinity/alkalinity of substrates. Of the true halophytes, Allenrolfea occidentalis alliance stands have the highest tolerance for salt, followed by Sarcocornia utahensis, Sarcobatus vermiculatus, and Atriplex nuttallii (Goodman 1973).
Floristics: Sites exhibit a range of soil moisture and salinity/alkalinity, from slightly brackish perennial springs to rarely inundated, hypersaline evaporate crusts. Areas with higher water tables and lower salinity support productive brackish marshes with tall graminoids and grasses such as Schoenoplectus americanus, including the ecologically similar Schoenoplectus pungens sensu FNA Editorial Committee (2002b), Phragmites australis, Typha angustifolia, Eleocharis spp., and Bolboschoenus maritimus along with taller forbs such as Helianthus nuttallii, Solidago spectabilis, and Euthamia occidentalis. West of the Great Plains these occur where freshwater springs emerge through salty or alkaline substrate, or creeks, streams or rivers flow through edges of salt flats or coastal salt marshes. These marshes tend to have steep moisture gradients to drier adjacent saline vegetation of the seasonal or ephemeral wetland component of this division.
Seasonal or ephemeral wetlands in the division have saline soils, a shallow to moderately deep water table and flood intermittently, but remain dry for most growing seasons. Salt crusts are common throughout. The flats are intermittently, seasonally to semipermanently flooded, usually retaining subsurface water into the growing season and drying completely only in drought years. They are often found in strongly saline-alkaline playa-like depressions, old lakebeds or in floodplains of major river systems where seasonal water inputs are limited, and often include some groundwater seepage in a matrix of mixed salt desert scrub. High rates of evaporation lead to alkaline water and soil conditions, with layers of salt-encrusted soils often accumulating near seeps. Perennial seeps often have bands of distinctive vegetation radiating outward, each with lower moisture requirements and higher salinity tolerance; for example, Anemopsis californica, Cressa truxillensis, Juncus cooperi, Juncus arcticus ssp. littoralis (= Juncus balticus), Bassia americana (= Kochia americana), Leymus triticoides, Leymus cinereus, Muhlenbergia asperifolia, Puccinellia spp. (including the endemic Puccinellia howellii), Salicornia rubra, Sesuvium verrucosum, Spartina gracilis, Sporobolus airoides, and Triglochin maritima. These herb stands also are reduced in stature as they decrease in moisture and increase in salinity, and ultimately are often surrounded by a low patchy turf of Distichlis spicata. These herbaceous stands grade into seasonal or ephemeral wetlands on playas or salt pannes, or irregularly flooded lowlands where halophytic shrubs, tend to be characteristic. Occasional shrubs tolerant of brackish but not highly salty water may occur in and adjacent to these herbaceous wetlands. These include Prosopis glandulosa, Prosopis pubescens, and Pluchea sericea (larger stands of these species occur in other riparian divisions).
Brackish marshes from the Great Plains eastward share many of these same species but also include related species such as Atriplex patula, Poa arida, Iva annua, Suaeda calceoliformis, and tend to grade into surrounding grasslands or agricultural landscapes. An increase in precipitation during exceptionally wet years can dilute the salt concentration in the soils, allowing for less salt-tolerant species such as Pascopyrum smithii or Hordeum jubatum to become dominant. In general there are no highly evaporative hypersaline playas or flats east of the 100th meridian.
Shrublands characteristic of salty warm or cool desert conditions are prevalent in this division throughout the West, but are not common from the Great Plains eastward. These periodically flooded shrublands consist of open to moderately dense stands of woody chenopods. Soils with shallow briny water tables tend to be dominated or codominated by succulent phreatophytes, including Allenrolfea occidentalis, Arthrocnemum subterminale, Sarcobatus vermiculatus, or Suaeda moquinii (= Suaeda nigra). Less salty soils with lower or no appreciable water table tend to have non-succulent-leaved species such as Atriplex canescens, Atriplex confertifolia, Atriplex gardneri, Atriplex parryi, Atriplex spinifera, Grayia spinosa, or Krascheninnikovia lanata. Areas of overlap occur with herbs such as Distichlis spicata, Bassia americana, and short perennial subshrubs such as Suaeda spp. and Frankenia salina (in California) occurring with taller shrubs of Atriplex or Sarcobatus.
Dynamics: Temporal shifts in salinity, inundation, and soil moisture strongly affect the dynamics of both herbaceous and woody components of this division. Although most western stands are subject to long periods of drought and are relatively stable in salinity, the more eastward and northward in range, the more likely are shifts in salinity based on periods of drought (higher) or wet cycles (lower). Permanent springs and seeps may also be affected by increases or decreases in salinity. In California, stands of Atriplex spinifera, Atriplex confertifolia, Suaeda moquinii, and other shrubs tend to be short-lived and shift depending on drought cycles (Sawyer et al. 2009). Others have found similar drought-related cycles in Allenrolfea or Sarcobatus (Trent et al. 1997, Gul et al. 2001).
Environmental Description: Climate: Most stands are characterized by long periods of drought during the summer months. Maximum or minimum temperatures range widely from well over 45°C to well below 0°C. Coastal fringes of the desert or semi-desert in southern California south to central Baja California, Mexico, have mild temperatures, but may have very high evaporation. Many of the key species of shrubs or wetland herbs have broad distributions and have broad temperature tolerance. Köppen climate system classifies the general distribution of this division within the Dry Climates (B) and include Bwh in subtropical Sonoran Desert ranging to Bsk in the northern Great Basin and the edges of the Great Plains. Large areas of the Great Basin are also Bwk.
Soil/substrate/hydrology: Salinity ranges from brackish to hypersaline. Texture ranges from peat and muck in perennial wetlands to heavy clay soils in and around playas or uplifted sea or lake beds in interior basins and valleys. Most soils are fine-textured and many have mineral crusts. Hydrology varies from permanent stream and spring flow to highly episodic flooding along desert streams and playa basins. Many stands of halophytic shrubs have fluctuating saline water tables.
Biogeography: Some of the diagnostic species for this division are members of very widely distributed genera (e.g., Suaeda). Species of Salicornia are found in both the Americas and Eurasia and Africa. Allenrolfea (a monotypic genus) is only in the New World. Sarcobatus is endemic to western North America. The marsh herbaceous genera are widespread in the Northern Hemisphere and some, such as Schoenoplectus, are distributed throughout the temperate and tropical zones of the world.
Geographic Range: This type occurs throughout much of the western U.S. in intermountain basins and extends onto the western Great Plains, into central Montana and into the warm deserts of North America, throughout California's Central Valley, San Joaquin Valley, and along its south coast extending into Baja California Norte, Mexico. The type is poorly developed eastward in the Great Plains primarily due to the dilution effect of higher summer rainfall and concomitant low evaporative conditions in the eastern part of North America.
Nations: CA, MX, US
States/Provinces: AZ, CA, CO, ID, MT, MXBC, MXCH, MXSO, NM, NV, OR, TX, UT, WA, WY
|US Forest Service Ecoregions (2007)|
Southwest Plateau and Plains Dry Steppe and Shrub Province
Confident or certain
Confident or certain
Plot Analysis Summary:
Salt tolerance along environmental gradients in Utah have been studied (Goodman 1973, Hansen 1975) showing a predictable gradation in species presence and dominance from high to lower salt tolerance. Peinado et al. (1994b) have sampled coastal and interior marshes in California and Baja California (Mexico) and shown ecological relationships between associations and alliances. Sampling and ecological distinction of the variety of associations and alliances in this division have been conducted in several California studies. Evens et al. (2014) have summarized these for the Mojave Desert and Buck et al. (2012) have summarized for the Sacramento and San Joaquin Valley area.
Confidence Level: Moderate
Confidence Level Comments:
Synonomy: > Alkali Sink (Keeler-Wolf 2007) [Keeler-Wolf only discusses Mojave Desert Alkali Sink which largely excludes Sarcobatus of the Great Basin, but does include brackish and saline marshes with Allenrolfea and Suaeda saline shrublands.]
< Mohavean Interior Marshland (Brown et al. 1980) [Only includes the wetland herbaceous alliances, does not treat the halophytic woody vegetation.]
< Saltbush series (as part of Great Basin Desert Scrub) (Brown et al. 1980) [Divide Saltbush series elements between cold-temperate Great Basin Desert Scrub, and warm-temperate desert lands in Mojave, Chihuahuan, and Sonoran desert scrubs, replicating the same relationships within 4 different regional formations.]
Concept Author(s): M.G. Barbour and W.D. Billings (2000)
Author of Description: G. Kittel and T. Keeler-Wolf
Acknowledgements: T. Keeler-Wolf thanks D. Faber-Langendoen and E, Muldavin for fruitful discussions and G. Kittel for editorial refinements.
Version Date: 28Oct2015
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