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Vegetation of the Northern Great PlainsWilliam T. Barker and Warren C. Whitman11Authors are Professor of Animal. and Range Sciences and Emeritus Professor of Botany, North Dakota State University, Fargo. The Northern Great Plains, as a distinctive region of the Great Plains as a whole, has been considered here to occupy that portion of the Plains lying between the foothills of the Rocky Mountains on the west and an imaginary line at the approximate 100th meridian on the east. The southern boundary has been placed on the North Platte River through Wyoming and Nebraska. The northern boundary has been set at the contact between the grassland (Fescue prairie) and the Boreal Forest, through southeastern Alberta, the southern third of Saskatchewan, and extreme southwestern Manitoba (Coupland, 1961). As a physiographic feature the Northern Great Plains actually extends well to the north of this arbitrarily fixed boundary (Fig. 1). Thus defined, the Northern Great Plains occupies an area about 950 miles long north-south, by an average 500 miles wide east-west. The total area within this region would thus be about 475,000 square miles (304,000,000 acres), of which approximately 150,000 square miles is in Canada and the remaining 325,000 square miles in the United States. It is customary to regard about 50 percent of the Great Plains as a whole to be in native range. For the Northern Great Plains it is here estimated that 160 million acres, or approximately 56 percent of the area is range and pasture land. Such estimates, of course, are notoriously inaccurate. It is important to remember that in the Northern Great Plains, especially in the more easterly portions, the rangelands are commonly intermingled with dryland farming areas and are used in combined farming-ranching operations. The primary ranching operation of the Northern Great Plains is the production of beef cattle, although there are significant numbers of sheep produced on the western ranges. It is estimated that over 90 percent of the animal-unit months of grazing on northern plains rangelands is consumed by beef cattle (Great Plains Agr. Council, 1976). By and large the rangelands are considered to be yearlong, but the grazing season is usually more limited and the feeding of hay and protein supplements during the winter months is a necessary practice throughout most of the area. Most of the rangeland in the Northern Great Plains is privately owned, supporting in addition to cattle and sheep a sizable and valuable big game population made up mainly of antelope, white-tail deer, mule deer, and some elk. The great Central Flyway for migratory waterfowl passes through the heart of the area, and the numerous wetlands of the glaciated section are critical to the maintenance of this priceless wildlife asset. Physical Background Three geological events have had great influence in determining the present physical characteristics of the Northern Great Plains. The first of these was the Cretaceous sea which spread over the Great Plains - Rocky Mountain region from the Arctic Ocean to the Gulf of Mexico some 100 million or so years ago (Hunt, 1974). Into this great sea many thousands of feet of sediments were deposited in nearly horizontal beds. Coastal plain and later continental deposits followed.
The second major event was the great Rocky Mountain uplift
toward the end of the Cretaceous period and extending into the Tertiary period
some 60 to 70 million years ago. This resulted in the raising and tilting of the
underlying plains strata, the shedding of vast amounts of sediment from the
mountains over the plains area to the east, and the extensive erosion of the
plains strata themselves. The third major event was the spread of the great ice sheets over most of the northern plains area. Through most of Pleistocene time, beginning some two million years ago and ending only about 10,000 years ago, the ice sheets advanced and retreated back and forth over a large portion of the Northern Great Plains area transporting vast quantities of rock and soil that they picked up, pulverized, and redeposited as glacial sediment (B1uem1e, 1977). The ice sheets spread over all of the Northern Great Plains in Canada, all but the southwestern portion of North Dakota, and most of the northern half of Montana to the mountains. In the east the ice sheets spread about to the present north-south valley of the Missouri River in North and South Dakota, through eastern Nebraska and a short distance into Kansas. Much of the topography in the plains area north and east of the Missouri River is about as it was left by the glaciers (Fenneman, 1931). A significant feature of the glacial advance has been the effect on the streams of the northern plains. Prior to glaciation they mainly drained northerly, north-easterly, or easterly. The ice front turned the Missouri River out of its northerly course in Montana and bent it sharply to the south in North Dakota. All the tributaries from the west down to and including the White River in South Dakota were blocked by ice and forced to become direct tributaries to the Missouri (Fenneman 1931). These drainage changes resulted in rapid downcutting by the affected streams through the soft, nearly horizontal strata of the plains sediments, forming in many cases the unique badlands areas characteristic of portions of a number of the streams in the Northern Great Plains. Almost all the streams draining to the Missouri, and the Missouri itself, have rough breaks or distinct badlands areas along at least part of their courses. As the net result of all these physiographic events, three recognizable regions have been defined for the Northern Great Plains. These are the Alberta Plain in Canada, the Missouri Plateau in southern Canada and in the United States, and a portion of the High Plains south of this (Hunt, 1974). The northern edge of the High Plains is defined by the Pine Ridge escarpment about 1000 ft. high at its maximum along the South Dakota-Nebraska boundary. Toward the Missouri River the Pine Ridge becomes less distinct, following the west side of the Missouri Valley. Part of the High Plains has been included here in the Northern Great Plains because by arbitrary definition the area has been extended to the valley of the North Platte River. In Canada, a portion of the Saskatchewan Plain, which properly lies in the Central Lowland (Coupland, 1961; Hunt, 1974), has also been included here as part of the Northern Great Plains rangelands. To some extent the same inclusion of portions of the Central Lowland has been made for parts of eastern North Dakota, South Dakota, and Nebraska. The Northern Great Plains area as a whole slopes from an altitude of 5,000 to 6,000 ft. at the base of the Rocky Mountains to about 1500 to 2000 ft. at its boundary with the Central Lowlands, some 500 miles to the east. As previously mentioned, the eastern boundary corresponds roughly with the 100th meridian, as do the 20-inch rainfall line and the intermittent escarpment marking the edge of the Missouri Plateau.
In Canada principal drainage is by way of the Saskatchewan River to the Nelson River and Hudson Bay. Farther south in Canada the Qu'Appelle and the
Souris, which loops into North Dakota, join the Assiniboine and eventually the north-flowing Red River to ultimately reach Hudson Bay. Farther west tributary streams come out of Canada to join with the Milk River in northern Montana, which in turn joins the Missouri River to
flow ultimately to the Gulf of Mexico. The Marias and the Mussellshell join the Big Missouri in Montana. The tributaries of the Yellowstone, the Big Horn, Tongue, and Powder join that river in Montana, with the Yellowstone itself joining the Missouri in extreme western North Dakota. The general direction of the streams here is northeasterly except for The Little Missouri River rising in extreme northeastern Wyoming flows north near the western boundary of North Dakota, then turns abruptly east to join the Missouri. From this point south the streams from the west flow easterly in roughly parallel courses to join the Missouri. In North Dakota this includes the Knife, Heart, and Cannonball Rivers. In South Dakota the Grand, Moreau, Cheyenne, Bad and White Rivers are involved. In Nebraska the Niobrara, Elkhorn, Loup and North Platte all follow this generally similar pattern. East of the plains area, but included in this discussion, the James River rises in North Dakota and flows almost directly south through South Dakota to join the Missouri River at the South Dakota-Nebraska line. Even farther east in North Dakota the Sheyenne River starts out in a southerly direction, but after flowing in that direction for over half its course, it abruptly turns east and north to join the Red River in its northerly flow to Hudson Bay. Both of these streams flow through significant grassland areas. Characteristic of the Missouri Plateau area of the northern plains especially are the often flat-topped erosion remnants that rise several hundred feet above the surrounding landscape. Commonly referred to as buttes, these features are usually capped by an erosion-resistant layer, such as sandstone, limestone, gravel, or slag formed by fusion of material over naturally burning coal veins. Locally this material is called "scoria," and its distinctive reddish color greatly enhances the scenic attractiveness of the region. Probably the largest of these landforms is the Cypress Hills, lying near the Canadian-U.S. border in southwestern Saskatchewan. This unique gravel-capped erosion remnant is nearly 80 miles long (east-west) and rises almost 2000 ft. above the surrounding plains (Fenneman, 1931). The most significant mountain formation in the Northern Great Plains section is the domed mountain uplift of the Black Hills in western South Dakota and northeastern W)7oming. This uplift parallels the Rocky Mountain front, 100 miles to the west, and is about 60 miles wide and 125 miles long, northwest to southeast (Fenneman, 1931). Erosion following the uplift of the dome has exposed the Precambrian crystalline rocks of the dome and reduced the uptilted surrounding strata. The highest peaks now stand about 4000 ft. above the plains to the east. On the western edge of the Missouri Plateau near the Rocky Mountains, a number of small mountain groups intrude into the plains. Some of these are domed mountains, while others are essentially volcanic intrusions. Among these mountain groups, standing several thousand feet above the surrounding plains, are the Sweetgrass Hills, Bearpaw, Judith, Highwood, Little Belt, and Big Snowy Mountains (Hunt, 1974). The significant feature of all of these mountains from the standpoint of the vegetation is that they support over at least a portion of their extent some type of montane forest. Soils For the most part, soils of the Northern Great Plains have been developed under a grassland cover which probably became an important part of the vegetation by late Tertiary time. Trees advanced and retreated across the plains in front of the glacial edge through Pleistocene time. It is generally accepted that grassland became the dominant vegetation over the Great Plains following the final melting of the glacial ice sheets (Bluemle, 1977). In Canada, eastern North Dakota and South Dakota, and northern Montana, surface materials from which soils were developed were principally glacial drift and largely unsorted morainic materials as deposited directly by the ice (Coupland, 1961). Action of water from melting ice has resulted in some separation and deposition of materials as outwash, ponded lake sediments, and stream deposits. Here and there some exposures of sedimentary bedrock from Cretaceous and Tertiary formations have persisted. South and west of the glaciated part of the Missouri Plateau sedimentary materials, sands, silts, clays, shales, and some limestones, were exposed as soil parent material. These deposits vary from marine, coastal plain, volcanic, and aeolian deposits, to relatively recent outwash materials from the Rockies toward the west. Especially significant in the High Plains portion of the area considered in this report is the great sandhill area of Nebraska, south and east of which are extensive loessial deposits. These deposits are apparently related to ice-age events, as are the sandhill areas of North Dakota and Saskatchewan (Hunt, 1974). The soils developed on the eastern and northern parts of the area are primarily mollisols with well-developed profiles, dark brown to nearly black in color and high in organic matter and bases (Singh et al., 1983). Except in the more eastern portions of the region, soils are calcareous with significant accumulations of calcium carbonate through most of the profile. While clays and silts are perhaps the most common particle sizes over the region, all textures are well represented (Aandahl, 1972). Topography is generally from nearly level to rolling, although portions of the region may be steeply rolling to hilly with relatively shallow, rocky profiles. Principal soils in the drier, western portion of the area are mainly aridisols, lighter in color and lower in organic matter, though having one or more pedogenic horizons. Aandahl (1972) maps perhaps 15-20 percent of the soils in the western part of the U.S. portion of the Northern Great Plains in this classification. Of these he indicates many may have more than 20 percent lithic material and may be hilly or even steeper. Entisols with poorly developed or no development of horizons occur infrequently over the area. However, the great sandhi11s area of Nebraska and other sandhi11s areas in the northern plains would be classified in this order. Aandah1 (1972) designates these soils as Psamments, some of which surely could be classed as mollic psamments, associated with Wisconsinan outwash (Soil Survey Staff, U.S.D.A., 1975). In addition, the badlands areas and river breaks of the region fall in the Entisol order being classed as Torriorthents (Aandah1, 1972).
The alfisols, gray to brown colored soils with well-developed horizons, occur in a very limited area, mainly where trees have Climate The climate of a region cannot be fully described by a single element such as precipitation or temperature (Packer, 1974), but the overwhelming importance of the amount and seasonal distribution of precipitation in the Northern Great Plains cannot be overemphasized. More important than average precipitation is the great degree of variability in precipitation (Van Dyne, 1975). The potentially great range from year to year in amount and timeliness of precipitation has been the factor most emphasized in the description of the climate of the Great Plains, and is well-established as the factor most affecting the production of seeded crops and native grazable vegetation. The region discussed in this report is considered to have two major climatic patterns - a semi-arid western portjon and a dry sub-humid eastern portion (Thornthwaite, 1941). Some areas of the western portion are classed as arid. From west to east, average annual precipitation ranges from about 12 inches near the mountains in Montana to about 20 inches at the eastern margin. From north to south, precipitation increases. Longtime records at Manyberries in Alberta show an annual average of 11.87 inches (Smoliak, 1986). At North Platte, Nebraska, the approximate southern end of the region, average precipitation is reported at 19.75 inches. Thus, for the region as a whole, the range north to south is about equal to the west-east range of annual average precipitation, namely 12-20 inches. The few mountain areas occurring in the Northern Great Plains, of course, have a more favorable moisture picture.
For the region as a whole, the winter is a drought period with generally less than one-fifth of the total annual precipitation However, the fluctuation in time of occurrence of precipitation and total amount received is very great and drought conditions may strike at any time. Weakly (1943) found from his analysis of tree ring records from western Nebraska that in a 400-year period, 154 years were drought years and 237 were wet years. Will (1946) found from similar studies in central North Dakota that over a period of 534 years, 302 years showed favorable moisture conditions and 238 were dry to drought years. The inevitability of dry years and drought seems well-established. The high temperatures, strong winds, and clouds of blowing dust that accompanied the great drought of the 30's will be long remembered on the northern plains. The frost-free period in the Northern Great Plains ranges from about 160 days at the southern end to about 120 days or less in Canada. Miles City, Montana in the central part of the region has an average frost-free period of 150 days. Plant growth generally begins prior to the beginning of the normal frost-free period, however, so that over much of the area growth of the cool-season species would have begun by early April. At the extreme northern edge of the plains grassland and at higher elevations, the frost-free season may be less than 100 days and plant growth would not be expected to begin much before the first of May (Coupland 1961). Snowfall can be expected over the region as a whole any time during the winter period (November-March) but may occur even earlier or later. Generally total amounts of snow vary between 20 and 40 inches. Snow cover is more continuous toward the northern part of the area, where it commonly persists for three to four months. However, the snow is not usually uniformly spread. A large portion is heaped into drifts where topography and obstructions affect wind-flow, while open fields and ranges may be scoured nearly free of snow cover. Often snowfall is accompanied by high winds, producing blizzard conditions. Mean annual temperatures range from about 50°F on the North Platte River near central Nebraska to as low as 32°F near the Fescue grassland border in Canada. Probably a better average for the Canadian portion of the area would be in the vicinity of 35-40°F (Clarke, Campbell, and Campbell, 1942). All portions of the area experience very high summer temperatures and very low winter temperatures. In the southern portion, maximum temperatures of over 100°F are frequently reached during the summer months, with temperatures of 110°F or over not uncommon. Temperatures below -40° have been recorded a number of times for this area. Farther north summer temperatures over 110° have been reached but are not common, while temperatures below -60°F are on record.
Evaluated from the standpoint of plant growth and production, the climatic regime of the Northern Great Plains obviously is one of Vegetation Basically the grassland vegetation of the Northern Great Plains over most of its range is surprisingly similar. Three major genera of grasses are distributed throughout the region. These are Agropyron, Stipa, and Bouteloua. Within these genera, western wheatgrass (Agropyron smithii) and thickspike wheatgrass (Agropyron dasystachyum) are the major wheatgrasses. Needle-and-thread (Stipa comata), porcupine grass (Stipa. spartea) and needlegrass (S. curtiseta) are the principal needlegrasses. Only blue grama grass (Bouteloua gracilis) is of major importance in the Bouteloua group, though side-oats grama (Bouteloua curtipendula) becomes significant in some associations. Allowing for the incursions of the bluestem grasses, big bluestem (Andropogon gerardii) and little bluestem (Andropogon scoparius) primarily in the easterly portion of the area, and for rough fescue (Festuca scabrella) types on the north and along the Rocky Mountain foothills, over 80 percent of the grassland vegetation of the area is readily accounted for by associations dominated by these species. At the same time, frequently occurring variations in exposure, geology, topography, and edaphic conditions, particularly as these factors affect soil moisture, have resulted in the development of numerous diverse and unique plant communities (Brown, 1971). The result of this is that despite the readily recognizable similarity of the vegetation as a whole, these differences have produced a striking and extensive array of plant communities that enliven the landscape throughout the entire northern plains area. The map presented in this discussion distinguishes 16 major vegetation types in the Northern Great Plains (Fig. 1). It must be recognized at once that this does not represent a full coverage of types by any means. "Badlands and River Breaks" is obviously not a vegetation type, but within these areas and areas closely associated with these topographic breaks, at least eight to 10 unique and distinctive vegetation types have been recognized by numerous investigators. "Montane Forest" as mapped also involves several different vegetation associations, as does the designation "Riparian Woodlands". No attempt has been made to map wetlands and specific alkaline-affected vegetation types, primarily because of scale difficulties, although some consideration is given to these in the text. Primary sources of the type designations, distribution, and boundaries have been the reports prepared by the Old West Regional Range Commission Committees of the various states: North Dakota (Shaver, 1977), South Dakota (Baumberger, 1977), and Wyoming (Shrader, 1977). For Montana, the map prepared by Ross and Hunter (1976) has provided an excellent basis for delineating the types. For Nebraska, vegetation reliance has been placed on the map prepared by Kaul (1975). The rangeland resource report of Hacker and Sparks (1977) bas also been very useful. In a number of cases composition and distribution of types have been checked in Johnston (1987). Most mapped types have been checked back against the "potential natural vegetation" map of Kuchler (1964). In Canada, type designations and distributions have been derived primarily from the papers of Clarke, Campbell, and Campbell (1942), Moss and Campbell (1947), Coupland and Brayshaw (1953), and Coupland (1950, 1961). In this presentation the word "type" has been applied to the recognizably similar assemblages of plant groupings occurring in essentially similar landscape positions under generally similar climatic and edaphic conditions regardless of ecological position. Nomenclature of plants in general follows that of the Great Plains Flora Assoc. (1986). The Tall Grass Prairie (bluestem prairie) type (Weaver and Clements, 1938) dominated primarily by big bluestem, Indiangrass (Sorghastrum nutans) , porcupine grass, switchgrass (Panicum virgatum). and prairie dropseed (Sporobolus heterolepis) has not been included in this discussion, lying as it does at the eastern margin of the area, properly speaking outside the Northern Great Plains. Most of this type has been converted to cropland. However, fragments of the type with essentially similar species composition extend far out into the northern plains prairies under favorable microenvironmental conditions. Wheatgrass - Bluestem - Needlegrass Type The Wheatgrass-Bluestem-Needlegrass type occupying
the eastern portion of the plains area and extending from central Saskatchewan
to the Platte River in Nebraska is essentially a transitional type lying
between the Bluestem prairie to the east arid the drier Wheatgrass-Needlegrass
type to the west. The type is not uniform in composition from north to
south by any means. Bluestem itself does not have much significance in
the Canadian portions of the type. Throughout its extent in this region,
the type mingles with the Fescue grassland, with remnants of this latter
type extending into northern North Dakota. Outliers of the aspen woodland
are dotted throughout the extent of the Canadian portion of the type and
again extend into northern North Dakota (Fig. 1).
Through much of this region the needlegrass portion of the type is largely
needlegrass, and thickspike wheatgrass along with Moving south into North Dakota, South Dakota and Nebraska, big bluestem progressively increases as a component of the type until on the loess hills of central Nebraska it becomes a major dominant (Hopkins, 1951). On drier sites or where severely disturbed by grazing pressure, throughout the Wheatgrass-Bluestem-Needlegrass type components from the more xeric Wheatgrass-Needlegrass type may become dominant, including western wheatgrass, needle-and-thread, and blue grama as well as other more xerophytic species. Through the central part of the Wheatgrass- Bluestem-Needlegrass (N. Dakota, S. Dakota), Kentucky bluegrass (Poa pratensis) has increased greatly in the cover and in many places is a major component of the vegetation. Scattered throughout the area from Nebraska into Canada are wetlands of various types. Many of these are salt-affected and support saline vegetation types. Dry saline-vegetation types are also frequent. Considering the full expanse of the type as mapped, the principal grass species of the Wheatgrass-Bluestem-Needlegrass type are western wheatgrass, bearded wheatgrass (Agropyron caninum subsp. majus var. unilaterale), slender wheatgrass (A. caninum subsp. majus var. majus), big bluestem, little bluestem, porcupine grass, needIegrass, needle-and- thread, green needlegrass (Stipa viridula) , sideoats grama, blue grama, Junegrass (Koeleria pyramided), prairie sandreed (Calamovilfa longifolia) , and now, Kentucky bluegrass. Important sedges are Carex eleocharis, threadleaf sedge (C. filifolia), C. pensylvanica, and C. heliophjla. Forbs are numerous and moderately abundant throughout the type. In general, many of the same species can be found through the entire range of the type. Such species include white aster (Aster ericoides), silver-leaf scurf pea (Psoralea argophylla), lemon-scurf pea (P. lanceolata), prairie coneflower (Ratibida columnifera), purple coneflower (Echinacea angustifolia), numerous milkvetches (Astragalus) species, purple locoweed (Oxytropis lambertii), gay-feather (Liatris punctata), scarlet gaura (Gaura coccinea), red false mallow (Sphaeralce coccinea), fringed sage (Artemisia frigida),white sage (A. ludoviciana), soft goldenrod (Solidago mollis). prairie goldenrod (Solidago missouriensis), other goldenrods, curly-top gumweed (Grindelia squarrosa), golden aster (Chrysopsis villosa), stiff sunflower (Helianthus rigidus) and Hood's phlox (Phlox hoodii). Shrubs are fairly frequent in the type, especially willows (Salix spp.), roses (Rosa spp.) and western snowberry (Symphoricarpos occidentalis). Other shrubs of importance include buffaloberry (Shepherdia argentea), silverberry (Eleagnus cummutata), chokecherry (Prunus virginiana), wild plum (P. americiana), northern hawthorn (Crataegus rotundifolia) and in some cases dwarf sagebrush (Artemisia cana). Tree growth is largely confined to favorable situations and will be discussed in relation to woodland types. However, it should be noted that the aspen (Populus tremuloides) occurs in small groves scattered in the Canadian portion of this type, also coming down into northern North Dakota. Other species which are of importance in favorable situations include American elm (Ulmus americana) (now being eliminated by Dutch Elm disease), bur oak (Quercus macrocarpa), green ash (Fraxinus pennsylvanica), and boxelder (Acer negundo). Wheatgrass - Needlegrass Type
The separation of the Wheatgrass-Needlegrass and the
Wheatgrass- Grama-Needlegrass types has been continued in this treatment. This separation seems to be justified because of the continued dominance of
the mid-grass component (wheatgrass and needlegrass) over the shortgrass component (blue grama and sedges) throughout much of the range of the
type. However, the shortgrass component has notably increased in this type. In the Canadian portion of the area, Coupland (1950) considers The Wheatgrass-Needlegrass type is shown on the map as extending from mid-Saskatchewan to below mid-South Dakota, into eastern Montana and northeastern Wyoming. Considerable cropland has been broken out of the native sod through most of this area, especially in the glaciated portion east and north of the Missouri River. Except when closely grazed, the principal aspect of the type is that of the mixed grass prairie with the mid-grasses, western wheatgrass and needle-and-thread overtopping the principal short grass component of blue grama grass and sedges. Prairie Junegrass, green needlegrass, plains reedgrass (Calamagrostis montanensis), and on the eastern edge Kentucky bluegrass, also occur frequently. Thickspike wheatgrass, slender wheatgrass, and occasionally bluebunch wheatgrass (Agropyron spicatum) enter into the species aggregation. Two shortgrasses, Sandberg bluegrass (Poa sandbergii) and buffalograss (Buchloe dactyloides) , are occasionally abundant, with Sandberg bluegrass rather widely distributed while buffalo grass may become important in special situations, often on solonetzic soils or bottomlands of small drainage ways. Another grass deserving special mention in this type is little bluestem. This grass is often abundant and conspicuous on the raw soils of small hilltops, side-slopes, and rough breaks throughout the range of the type. Wheatgrass-Grama-Needlegrass Type
The Wheatgrass-Grama-Needlegrass type, shown on the map as extending from southeastern Alberta and southwestern
Saskatchewan to northeastern Wyoming, indicates the increasing importance of blue grama grass in the cover in relation to
increasing aridity of the climate as the Rocky Mountains are approached. In the Canadian portion of the
type, the needlegrasses (S. comata and S. curtiseta) and grama
components of the vegetation assume major importance with the wheatgrass
component (A. smithii and A. dasystachyum) being relatively minor
(Coupland, 1950). The wheatgrass component becomes more important In northwestern South Dakota, blue grama grass is notably absent over an appreciable area where the vegetation has developed on dense clayey soils. Needle-and-thread also is scarce, though green needlegrass is often fairly abundant. This situation has been recognized on the map by the designation of the Wheatgrass Type (Fig. 1). Considering the Wheatgrass-Grama-Needlegrass type as a whole, there is no question but that blue grama grass has increased greatly in importance as the result of grazing. Buffalo grass also becomes increasingly important in the type, especially toward the southern section. In many places the shortgrass aspect of the type appears to predominate. Probably the most significant alteration of the type that has occurred is the widespread increase of big sagebrush (Artemisia tridentata). Over much of the type, this species has become so important in the cover as to give the type the general appearance of a sagebrush-grass type, and in some cases it has been so mapped. Big sagebrush extends into western North Dakota, South Dakota, and Nebraska, but dwarf sagebrush, while occurring throughout the type, seems to be the major sagebrush species on the eastern and northern fringes of the type and the primary sagebrush species which extends eastward into the Wheatgrass-Needlegrass type. In addition to the major grass dominants, other grass species showing increased occurrence include red threeawn (Aristida purpurea var. robusta), Indian ricegrass (Oryzopsis hymenoides), plains muhly (Muhlenbergia cuspidata) , and bluebunch wheatgrass (Agropyron spicatum). On salty soils, inland saltgrass (Distichlis spicata var. stricta), alkali cordgrass (Spartina gracilis), basin wildrye (Elymus cinereus) , foxtail barley (Hordeum jubatum) and little barley (H. pusillum). Nuttall alkaligrass (Puccinellia nuttalliana), squirreltail (Sitanion hystrix) and tumblegrass (Schedonnardus paniculatus) become common. Shrub species on similar salt-affected soils include greasewood (Sarcobatus vermiculatus), shadscale (Atriplex confertifolia) Nuttall saltbush (Atriplex nuttallii), four-wing saltbush (A. canescens), and winterfat (Ceratoides lanata). The annual bromegrasses, cheatgrass (Bromus tectorum), and Japanese brome (B. japonicus) occur frequently on deteriorated rangelands through the Wheatgrass-Grama-Needlegrass type. Wheatgrass - Grama Type Through central and southwestern South Dakota and into extreme northwestern Nebraska, needle-and thread is scarce on the dense, clay soils of the region, and Baumberger (1977) has designated the vegetation found here as the Wheatgrass-Grama type. This designation has been adopted here and the extent of the type is shown in Fig. 1. Some green needlegrass is found throughout the type and buffalograss becomes increasingly important with increase in grazing pressure. Blue Grama - Buffalograss Type On the tablelands of northwestern Nebraska and extending into Wyoming north of the North Platte River, the Blue-Grama-Buffalograss type is developed (Kaul, 1975). This appears to be-an-extension of the northern grama-buffalograss prairie of Kuchler (1974). While the mid-grasses, western wheatgrass, needle-and-thread, and others are present to some extent, the aspect of the vegetation is definitely that of the shortgrass type. Figure 1 indicates the limited extent of this type in the Northern Great Plains as here defined. Sandhills Prairie Type The vegetation of the great sandhills area of Nebraska has been mapped here as Sandhills Prairie. This great grassland area extends a short distance into South Dakota and is commonly given an area of 17,000 to 18,000 square miles. The area supports a grassland cover that has shown surprisingly little degeneration since grazing of domestic livestock began in the region (Branson, 1985). The vegetation is fundamentally that of a tall grass prairie with big bluestem, little bluestem, sand bluestem (Andropogon hallii), prairie sandreed, needle-and-thread, sand dropseed, Indian ricegrass, and switchgrass as major species. Typical blowouts with characteristic vegetation are found in the area, particularly in the drier, western portion of the type. Here such additional species as blowout grass (Redfieldia flexuosa), sandhill muhly (Muhlenbergia pungens), and sand dropseed (Sporobolus cryptandrus) occur. Forbs are abundant in the Sandhills Prairie with such species as leadplant (Amorpha canescens), yucca (Yucca glauca), lemon scurf pea, silky prairie clover (Dalea villosa), purple prairie clover, goldenrods, (Solidago altissima, S. missourensis, S. canadensis and S. gramnifolia), sunflowers (Helianthus spp.), and many others being conspicuous and common. The sandhills area is dotted with many wetland areas supporting dense aquatic vegetation and abundant wildlife populations. Sandhill areas are scattered throughout the Northern Great Plains. Many of these areas are quite small and separate mapping of them was impossible. However, the area along the Sheyenne River in southeastern North Dakota and the large area near Swift Current, Sask. have been mapped as Sandhills Prairie. The Sandhills Prairie in eastern North Dakota is quite similar to the eastern portion of the Nebraska Sandhill Prairie. However, the sandhills area of Saskatchewan does not have a significant bluestem component in the established vegetation. Shrubs and trees are fairly common on favorable sites, especially in the northern sandhill areas. Distribution ranges from scattered individuals, to thickets, to well-developed savanna. Willows, roses, chokecherry, wild plum, and western snowberry are common. Creeping juniper (Juniperus horizontalis) and common juniper (Juniperus communis) occur irregularly. Eastern red cedar (J. virginana) is frequent to the south, savanna type developments of bur oak (Quercus macrocarpa) are found to the north, and the trembling aspen and cottonwood (Populus deltoides) often occur as clumps, groves, or in the case of the cottonwoods, as scattered individuals. Foothills Prairie The fescue grassland, originally dominated by the tussock-forming rough fescue (Festuca scabrella) and commonly associated with the dark soils fringing the boreal forest zone in Alberta and Saskatchewan, has here been designated as Foothills Prairie. This is an older usage and may not be ecologically sound, but it does describe its present general occurrence. On the map (Figure 1), the type is shown as a major type in the aspen parkland and the Rocky Mountain foothills extending as a fringe from Alberta far south into Montana. Mueggler and Stewart (1980) find a rough fescue-dominated type as far south as the foothills of the Madison Range. Also the type partially fringes most of the outliers of the Rocky Mountain system in Montana as shown on the map. On the east, the map (Figure 1) shows remnants of the type mingled with the Wheatgrass-Bluestem-Needlegrass type extending across Saskatchewan and southwestern Manitoba into northern North Dakota; this is definitely not a foothill area, but shows strong association with the aspen grove region bordering the boreal forest. Coupland and Brayshaw (1953) find a rough fescue type developed as a fringe above 4,000 ft. on the north and east slopes of the Cypress Hills. Principal grass dominants and associates, in addition to rough fescue, include oatgrasses (Danthonia parryi and D. intermedia), bluebunch wheatgrass, slender wheatgrass, western and thickspike wheatgrasses, needlegrass (north), Columbia and Richardson needlegrasses (Stipa columbiana, and S. richardsonii) (south), needle-and-thread, prairie Junegrass, Idaho fescue (Festuca idahoensis), spike oat (Helictrotrichun hookeri) , and threadleaf sedge. Kentucky bluegrass and in some cases the annual bromes are found in the type. Shrubby cinquefoil (Potentilla fruticosa), big sagebrush, and trembling aspen are woody species that now are frequently found in the type. In addition to many of the forbs from the lower altitude grasslands, such species as lupines (Lupinus spp.), tall larkspur (Delphinium occidentale), sticky geranium (Geranium viscosissimum), and arrowleaf balsamroot (Balsamorhiza sagittata) appear in the foothill development of the type. Pacific Bunchgrass Type Only a small area in south-central Montana has been mapped as representing the Pacific Bunchgrass type. The type has been so designated because bluebunch wheatgrass is usually the major dominant, as in the bunchgrass vegetation west of the Rocky Mountains. Idaho fescue (Festuca idahoensis) is present in some situations, especially at higher altitudes, but in many cases is poorly represented in the cover or may be entirely absent. The Pacific Bunchgrass type as here designated is by no means restricted to the boundaries indicated on the map. Wright and Wright (1970), Brown (1971), Jorgenson (1979), and Mackie (1970) report it as occurring extensively well to the east and north of the mapped area. Usually big sagebrush is associated with bluebunch wheatgrass as a major dominant of the type. Dodd (1970) even reports the species as an understory dominant in ponderosa pine stands in western North Dakota. In its Montana plains range, bluebunch wheatgrass is often associated with pine and Rocky Mountain juniper stands. Major grasses commonly associated with bluebunch wheatgrass in these stands include western wheatgrass, sideoats grama, little bluestem, red three-awn, needle-and-thread, plains muhly, prairie Junegrass, blue grama, and thickspike wheatgrass. Shrubs, in addition to big sagebrush, frequently found in the plains occurrence of the type include silver sagebrush, rabbitbrush (Chrysothamnus nauseosus), eriogonum (Eriogonum multiceps), western snowberry (Symphoricarpos occidentalis), snakeweed (Gutierrezia sarothrae), fragrant sumac (Rhus aromatica) and fringed sagebrush. Forbs are usually not very-abundant in the type. Included with others are such species as yarrow (Achillea millefolium), white prairie aster, prairie chickweed (Cerastium arvense), American vetch (Vicia americana), scarlet gaura, and plains prickly pear (Opuntia polyacantha). Badlands and River Breaks The vegetation of the badlands and steep river breaks throughout most of the Northern Great Plains is so distinctive and unique that it deserves separate classification. It has already been mentioned that the major badlands areas in the region are between the Cheyenne and White Rivers in South Dakota (mainly along the White River) and along the Little Missouri River in North Dakota. Extensive areas of badlands also occur in southeastern and south central Montana along the tributary drainages of the Yellowstone and Missouri Rivers. Roth the Yellowstone and the Missouri Rivers have numerous sharply eroded breaks, steep bluffs, and essentially badlands areas throughout much of their courses through the upper plains (Fig. 1). Characteristic of these steep, eroded broken areas are abrupt changes in the nature of the exposed soil and geological materials, topography, slope, exposure, degree of erosion, and sodium accumulations. At the same time there are intermixed gentle slopes, rounded knolls, and nearly level plateau-like remnants which show considerable soil development. Corresponding to the abrupt changes in edaphic and micro-environmental factors are abrupt changes in vegetation patterns. In general, north- and east-facing slopes have more mesic conditions, while south- and west-facing slopes may be extremely xeric. The less eroded areas showing substantial soil development often support a typical grassland cover. Knolls and less-steep breaks frequently show development of pine savanna-type cover with scattered Ponderosa pine (Pinus ponderosa) or Rocky Mountain juniper-pine associations. On steep east and north-facing slopes, nearly pure dense stands of juniper may be developed. Along the Missouri River in north-central Montana, Mackie (1970) found Douglas fir (Pseudotsuga menziesii) associated with Rocky Mountain juniper on moderate to steep northerly exposures under cool, mesic conditions. In western North Dakota and South Dakota and extending south into Nebraska and western into eastern Montana the interesting vegetation type now designated as the "green-ash hardwood draw" type is frequently associated with the relatively mesic slopes and drainage ways of the region (Goetz, 1988). American elm, boxelder, chokecherry, hawthorn, wild plum, buffaloberry, western wild rose (Rosa woodsii) , and Juneberry (Amelanchier alnifolia) are frequently associated with the dominant green ash in this type. Western snowberry is usually abundant in the understory. The cottonwood, while primarily a tree of the stream floodplains, does occasionally develop as isolated individuals or small groups in the hardwood draw type. On the steeper slopes shrub types are developed. Big sagebrush is probably the most frequently occurring shrub in these situations. It is often associated with rabbitbrush and shadscale (Atriplex confertifolia). Long-leaved sagebrush (Artemisia longifolia) is also present. Bluebunch wheatgrass often becomes a major associate in the type. Fragrant sumac may become a dominant shrub species, especially on upper slopes where porcellanized fragments are present. Shrubby cinquefoil may also be frequent in such situations. Bluebunch wheatgrass again is a major associate, especially to the west. Salt (sodium) accumulations may occur at almost any place on the eroding slopes or on the footslopes and benches at the base of slopes. On the slopes, shadscale and Nuttall's saltbush frequently mark these salt accumulations. Eriogonum is also frequent here. At the base of the slopes, well developed stands of greasewood (Sarcobatus vermiculatus) and shadscale are frequently found. Big sagebrush is usually present. Frequently winterfat and seablite (Suaeda fruticosa) are also present. Often inland saltgrass is part of the understory. Flesland and Whitman (1964) and Brown (1971) have pointed out the similarity between these vegetation types and the salt-desert vegetation type of the Great Basin. Pine Savanna The woody vegetation type characterized by scattered stands of ponderosa pine frequently associated with Rocky Mountain juniper, which occurs extensively on the rough uplands through central and eastern Montana into northwestern Wyoming, western South Dakota, and to a very limited extent in western North Dakota, has been here designated as the Pine Savanna type. This designation follows the usage of Baumberger (1977). The general concept was apparently used by McIntosh (1931) in reference to the communities of evergreens on the foothills of the Black Hills and in the White River Badlands. On the map (Figure 1) the type has been shown as fringing the Black Hills on the east and south with the White River Badlands and Pine Ridge stands to the southeast. The Pine Ridge area extends into northwestern Nebraska. Other relatively small stands of the type have been mapped on upland sites in northwest South Dakota and eastern Montana. A small but significant stand of the type occurs in the badlands area of south- western North Dakota. The broken to rolling upland area along the Yellowstone southeast and north of Billings bas been mapped as supporting the Pine Savanna type, even though there is much inter spersed grassland in the area. Through the extent of the Pine Savanna type, ponderosa pine is the dominant and characterizing tree, though Rocky mountain juniper is frequently associated with it. Because of the relatively large amount of open grassland usually occurring with the trees in the type, the association has been described as a forest-grassland complex. The grassland component is often dominated by western and thickspike wheatgrass, needle-and-thread, blue grama grass, green needlegrass and little bluestem. Bluebunch wheatgrass is usually present and often becomes a major dominant of the understory beneath the trees. Farther west it may become the major grassland species representative of the type. Western snowberry often is important in the tree understory. Black Hills Pine Forest The Black Hills Pine Forest is by far the largest single forest unit in the Northern Great Plains and has been described in detail by McIntosh (1931). Over most of its range in the higher hills ponderosa pine grows in open park-like stands. On the foothills the pines become more scattered, taking on the savanna-like appearance previously described. In some cases second-growth trees form dense, nearly closed stands. In the deep cool canyons of the interior ranges white spruce (Picea glauca) is found. Associated with the spruce is paper birch (Betula papyrifera).
On cutover or burned land, especially in the northern sections,
aspen and paper birch form extensive communities, with occasional relict pines scattered throughout. Willows,
Juneberry, beaked hazelnut
(Corylus cornuta), and chokecherry are often important in the In the eastern and northern foothills, especially along streams, a deciduous forest type is developed. Principal dominants are green ash, bur oak, American elm, boxelder, and to a lesser extent hackberrv (Celtis occidentalis). Northward the bur oak becomes the dominant tree.
On the western foothills shrub types become important. Big sagebrush and sand sagebrush
(Artemisia filifolia) occupy extensive The grasses of the mixed prairie extend into the foothills, the pine savanna and the larger park-like areas of the major forest region. Included are western wheatgrass, bluebunch wheatgrass, needle-and-thread, green needlegrass, prairie Junegrass, blue grama, hairy grama (Bouteloua hirsuta), and buffalograss. Needleleaf and threadleaf sedges are common. In some places tall grass prairie remnants are found with big and little bluestem, Indian grass, side-oats grama, and prairie sandreed as major species. Forbs of both grassland types are those common to the types. Montane Forest Forests found on the upper levels of the Rocky Mountain outliers in western Montana and on the Cypress Hills in Saskatchewan have been placed in this category. These forests are not of the same composition in all cases. Most frequently the vegetation at all but the highest elevations are forest-grass complexes, with Douglas fir and ponderosa pine being the principal tree species. At the highest altitudes, as in portions of the Highwood Mountains and Big Snowy Mountains, subalpine fir (Abies lasioscarpa), Douglas fir, and Engelmann spruce (Picea engelmannii), become the principal tree species of this forest type. In a few cases elevations above tree-line are reached in these small, outlying, ranges. Bluebunch wheatgrass, Idaho fescue, Columbia needlegrass, spike fescue (Hesperochloa kingii), prairie Junegrass, needle-and-thread, oatgrass and Sandberg bluegrass are major species in the grassland phase of the complex and often a part of the understory in the forest phase. Arrowleaf balsamroot, lupine (Lupinus sericeus), sticky-leaved geranium, bluebells (Campanula rotundifolia) , and prairie smoke (Geum triflorum) are common forb associates. Western snowberry, white spiraea (Spiraea betulifolia), and bearberry (Arctostaphylos uva-ursi) are common shrubs in the forest understory.
Coupland (1950) considered the forest vegetation of the Cypress
Hills in Saskatchewan to be similar to the submontane forest of the Upland Woodlands Scattered acr0SS the northern plains are various types of tree growth which have been categorized here as Upland Woodlands. Most commonly these are associations dominated by aspen, bur oak, green ash, or junipers. Normally these types are associated with favorable habitats, and do not make up any sizable portion of the total vegetation. However, to the north into Canada and at higher elevations westward the aspen becomes increasingly abundant. To the south and west the junipers become more important. No attempt has been made to map more than a small portion of these woodlands; primarily the map (Figure 1) shows only a few of the larger areas of Upland Woodlands. The aspen type, dominated by trembling aspen, often has balsam poplar (Populus balsamifera), paper birch, green ash, and sometimes bur oak as associated tree species. Shrubs that frequently occur are beaked hazelnut, western snowberry, Juneberry, red raspberry (Rubus idaeus), and bittersweet (Celastrus scandens). Mountain birch (Betula occidentalis) is also present in some stands. Grasses are usually not prominent in the type, although rough-leaved ricegrass (Oryzopsis asperifolia) and little seed ricegrass (Q. micrantha) occur frequently. Long-beaked sedge (Carex sprengelii) is also a common associate in the understory. Forbs are fairly important in the understory of the type and include such species as wild lily-of-the-valley (Maianthemum canadense), wild sarsaparilla (Aralia nudicaulis) , bedstraw (Galium triflorum) , wild strawberry (Fragaria virginiana), various violets (Viola spp.), anise root (Osmorhiza longistylis), and black snakeroot (Sancula marilandica). In some cases, as in the Turtle Mountains of northern North Dakota and southern Manitoba, it is thought that as the result of fire, the aspen type has replaced a woodland previously dominated by bur oak. In Canada, as well as occurring in the grassland as frequent outliers of the Boreal Forest, the aspen type commonly fringes the lower portion of the scattered highlands such as the Duck Mountains, the Riding Mountains, and the Porcupine Hills. Woodland types dominated by bur oak are fairly common through. the region but are usually not extensive. The type is mostly a feature of the more easterly portion of the Northern Great Plains. Bur oak is the principal tree species, but green ash, American elm, boxelder, aspen, and occasionally ironwood (Ostrya virginiana) are associated with the oak. Less commonly hackberry occurs in the association. The association may occur as a more or less savanna type of growth, as in the sandy areas of eastern North Dakota, as scattered groves in favorable situations, or as a fairly dense woodland, usually at somewhat higher elevations. A fairly common occurrence is as a fringe woodland in the upper portion of shallow drainages. Chokecherry, hazlenut, western snowberry, Juneberry, and gooseberry (Ribes missouriense) are usual shrub associates. Long-beaked sedge, Kentucky bluegrass, and false melic (Schizachne purpurascens) are frequently part of the understory. The green ash type, while commonly associated with woody draws, lower terraces, and small valley bottoms, does sometimes appear as a dominant type on north or east-facing slopes in upland positions. Usually the stands are relatively small in size, a few acres only. Tolstead (1947) reports stands 15 to 20 acres in size in northwestern Nebraska. Associated with the green ash most frequently are American elm and boxelder. Hackberry occasionally occurs. Rocky Mountain juniper may occur in the type, and Tolstead (1947) reports the green ash as growing with ponderosa pine on east slopes in northwestern Nebraska. Juniper woodlands are fairly common throughout the western part of the Northern Great Plains. Rocky Mountain juniper is the principal species of this type. To the south the eastern red cedar becomes relatively frequent. While dense stands of Rocky Mountain juniper on favorable sites are not uncommon, they most frequently occur in relatively open stands of scattered individuals. The Rocky Mountain juniper is usually on upland slopes on relatively dry, rough, broken terrain. Common associates in such situations are ponderosa pine and shrubs such as big sagebrush, bitterbrush (Purshia tridentata) buckbrush, fragrant sumac, and rabbitbrush. Western wheatgrass, bluebunch wheatgrass, thickspike wheatgrass, blue grama, Kentucky bluegrass, and other grasses from the surrounding grassland are common. Dense stands on north and east-facing slopes in western North Dakota have a characteristic grass, little ricegrass, as a part of the understory. Riparian Woodlands By far the most important riparian woodland type in the Northern Great Plains is the Cottonwood Type which occurs on the floodplains of the larger rivers and streams, in subirrigated valleys, and as small groves or as scattered individual trees along minor drainages. The cottonwood (Populus deltoides) is the dominant tree, with green ash, boxelder, American elm, hackberry, peach-leaved willow (Salix amygdaloides), and occasionally bur oak as associates. The junipers, Rocky mountain juniper and to the south eastern red cedar, may become common in the type. The sandbar willow (Salix exigua) sometimes forms dense thickets along the streambank side of the woodland. Best development of the type has been in the bottomlands of the Missouri River through North and South Dakota and into Montana, along the Little Missouri River in southwestern North Dakota, and along the Yellowstone River from its junction with the Missouri River far up the river into the foothills of the Rocky Mountains. The cottonwood type shows excellent development along the tributaries to the Missouri in South Dakota, the Cheyenne and lower White Rivers, and along most of the course o£ the North Platte River through Nebraska. In its best development the cottonwood trees may reach heights of 80 to 100 ft. and form a fairly dense forest-like stand. More commonly the mature trees may be 50 to 60 ft. tall with a fairly open stand permitting the growth of a significant understory of shrubs, grasses, and forbs. Shrubs in the more open woodlands include such species as chokecherry, western wild rose, western snowberry, buffaloberry, dogwood (Cornus stolonifera), fragrant sumac, silver sagebrush, golden currant (Ribes odoratum), gooseberry (R. setosum), and poison ivy (Toxicodendron radicans). Bittersweet, wild grape (Vitis vulpina), thicket creeper (Parthenocissus vitacea) and western Clematis (Clematis ligusticifolia) are vines which occur in the type. Grasses of the understory include Canada wildrye (Elymus canadensis), slender wheatgrass, Virginia wildrye (Elymus virginicus), prairie sand reed, needle-and-thread, green needlegrass, marsh muhly (Muhlenbergia racemosa), reed canary grass (Phalaris arundinacea) prairie cordgrass (Spartina pectinata), and Kentucky bluegrass. Several sedges are also associated with the grasses. Forbs found in the understory include such species as yellow and white sweetclover (Melilotus officinalis and M. alba), false Solomon's seal (Smilacina stellata), dogbane (Apocynum cannabinum), wild licorice (Glycyrrhiza lepidota), fringed loosestrife (Lysimachia ciliata), meadow rue (Thalictrum venulosum) and numerous others. Agricultural land usage in the larger valleys has done much to reduce the extent of the cottonwood type. The construction of the large dams on the Missouri River in Montana and North and South Dakota has eliminated by flooding much of the previous extent of the type. Furthermore, the stabilization of water levels, river channels, and reduction of flooding has largely eliminated the unstable sandbar habitat so critical to the establishment of new cottonwood stands. For the future it would appear that much of the remaining cottonwood woodland will not be able to reestablish itself and will probably be replaced by other trees. Two other riparian woodland types come into the borders of the Northern Great Plains from the east. These are the Elm-Ash type and the Elm-Ash-Basswood or Plains Hardwood type (Clambey, 1986). Small developments of the Elm-Ash type extend along the rivers and streams for a considerable distance into the plains, but stands of the type become smaller and more scattered as the upper reaches of the streams are approached. Downstream in the lower valleys the Elm-Ash type assumes the appearance of a true gallery forest with tall trees. and nearly complete canopy cover. The major trees of the Elm-Ash type include, of course, the American elm (now partially eliminated as the result of Dutch elm disease), green ash, box elder, cottonwood, bur oak, and occasionally hackberry and trembling aspen. Shrubs are mainly similar to those in the Cottonwood Type understory, including chokecherry, Juneberry, western snowberry, gooseberry, currants, and poison ivy. Shrubs become less abundant as the canopy becomes more dense and shade-tolerant forbs, grasses and sedges increase. Where the tree stands are more open, Kentucky bluegrass has become an important grass in the understory. Where the type develops under the most favorable conditions, it shows considerable resemblance to eastern deciduc1us forests, with limited understory development. The Elm-Ash-Basswood type occurs mostly outside the Northern Great Plains area, with one notable exception. In northern Nebraska the type extends far up the Niobrara River to meet and mingle with ponderosa pine (Kaul, 1975). Small extensions of the type also occur along the Elkhorn and Loup Rivers in the same general region. The principal difference between this type and the Elm-Ash type is the presence of the basswood as a major component of the stands. Kaul (1975) finds the general aspect of these bottomland forests to be largely unchanged in spite of extensive grazing and cutting. Miscellaneous Considerations Aside from shrub types involving mixtures of big sagebrush and silver sagebrush with grassland types to produce sagebrush-grass complexes, shrub types are not major range types in the Northern Great Plains. This is not to say that shrub types are not important in the vegetation of the region. They provide variety in the grazing diet, shelter for livestock and wildlife, changes in the aspect of the landscape, and are important for erosion control. On certain saline clay soils shrub types may be fairly extensive. In this treatment, however, the choice was made not to attempt to delineate shrub types at this time. Most shrub types commonly occurring have been mentioned in discussions of other vegetation types. No discussion of the extent and importance of introduced grasses and legumes in the Northern Great Plains has been attempted here. Obviously these grasses and legumes are an invaluable forage resource in this area, where there is such great potential for their successful establishment and utilization. They deserve separate treatment. Finally, only a brief mention of wetlands vegetation has been made. The Northern Great Plains has numerous prairie potholes which result mainly from unintegrated drainage patterns and perched watertables. There are many man-made stock ponds which become quite similar to natural wetlands. Stewart and Kantrud (1971) developed a classification of natural ponds and lakes in the glaciated prairie region. The classification seems to work well for long established man-made ponds. Due to the moisture gradient that develops around wetlands, wetland vegetation can be grouped into zones. Each of these zones are characterized by a different assemblage of plant species. These zones for wetlands in the Northern Great Plains are as follows: wetland-low- prairie zone; wet-meadow zone; shallow-marsh zone; deep marsh zone; permanent-open water zone; intermittent-alkali zone; and fen (alkaline bog) zone. Plant species found in wetlands are very ubiquitous and each zone has its own assemblage of plant species. Stewart and Kantrud's (1971) classification is based on the water permanence, water quantity, water quality and the vegetation zones of each class of wetland. Seven major classes of wetlands have been recognized by Stewart and Kantrud (1971). These are as follows: ephemeral ponds; temporary ponds; seasonal ponds and lakes; semi- permanent ponds and lakes; alkali ponds and lakes; and fen (alkaline bog) ponds. In the ephemeral ponds the wetland-low prairie zone dominates the deepest part of the pond basins. Often these areas are wet for only several weeks each year. Kentucky bluegrass, meadow anemone (Anemone canadensis), western snowberry, white aster, switchgrass, sedge (Carex brevior), big bluestem, white camas (Zigadenus elegans) and wild lily (Lilium philadelphicum) are common in the wetland-low prairie zone of this wetland class. The temporary pond has two vegetation zones, wetland-low-prairie zone and wet meadow zone. The wet meadow zone dominates the deepest part of the temporary pond with the peripheral wetland-low-prairie zone being present. The temporary pond is usually wet for several weeks during the growing season. The wet meadow zone is characterized by the following plants: fowl bluegrass (Poa palustris), wooly sedge (Carex lanuginosa), panicled aster (Aster simplex), spikerush (Eleocharis smallii), foxtail barley, northern reed grass, prairie cordgrass, Baltic rush (Juncus balticus), American germander (Teucrium canadense), hedge nettle (Stachys palustris), field mint (Mentha arvensis), and field sow thistle (Sonchus arvensis). The species for the wetland-low-prairie zone are the same as given for the ephemeral ponds. Seasonal ponds and lakes have three vegetation zones. These are: wetland-low-prairie zone; wet meadow zone; and shallow-marsh zone. These wetlands are wet for four to five weeks, usually in the spring. The shallow-marsh zone dominates the deepest parts of the seasonal ponds and lakes. The plants of this zone are: bur reed (Sparganium eurycarpum), water plantain (Alisma subcordatum), American sloughgrass (Beckmannia syzigachne), slough sedge (Carex atherodes), water smartweed (Polygonum amphibium), reed canary grass (Phalaris arundinacca) and water parsnip (Sium suave). The species of the wet meadow and the wetland-low-prairie zones have been previously discussed. The semipermanent ponds and lakes have a central deep-marsh zone. These wetlands are wet most of the growing season but sometimes dry up in August. Plants characteristic of the deep-marsh zone are: sago pondweed (Potamogeton pectinatus), baby pondweed (P. pusillus), claspingleaf pondweed (P. richardsonii), common bladderwort (Utricularia vulgaris), hornwort (Ceratophyllum demersum), white water crowfoot (Ranunculus aquatilis), and American milfoil (Myriophyllum exalbessens). In the shallow-marsh zone of this wetland class the following plants are common: softstem bulrush (Scirpus veliaus), hardstem bulrush (S. acutus), river bulrush (S. fluviatilis), prairie bulrush (S. paludosus), broad-leaved cattail (Typha latifolia), and narrow-leaved cattail (T. angustifolia). These emergent species offer wildlife considerable cover and therefore are very important to wildlife. The species previously discussed for the shallow-marsh zone, the wet meadow zone and the wetland-low-prairie zone are also found in these zones of this wetland class. Permanent ponds and lakes have vegetation zones similar to the semipermanent ponds and lakes. Wetlands of this class usually are deep enough to have an open water zone in which few plants are found. These wetlands usually have water all year. In alkaline ponds and lakes the species diversity in the various vegetation zones is often greatly reduced. Widgeon grass (Ruppia maritima) is a common submerged species in this wetland class. A white soil zone (usually caused by crystals of sodium sulfate) usually surrounds this wetland class. Fen ponds are alkaline bogs which are fairly common in the Northern Great Plains. Species which are characteristic of these are: broad- leaved cattail, narrow-leaved cattail, common reed grass (Phragmites australis), softstem bulrush, sedge (Carex aquatilis), hoary willow (Salix candida), arrowgrass (Triglochin maritima), fringed gentian (Gentianopsis procera), Kalm's lobelia (Lobeli kalmii), northern grass- of-Parnassus (Parnassia palustris), and mare's tail (Hippuris vulgaris). Wetland vegetation supplies food and cover for many species of wildlife and is essential to the perpetuation of the great populations of wild ducks, geese, swans and cranes which migrate from the Gulf regions to the near Arctic and return each year. Literature Cited Aandahl, A.R. 1972. Soils of the Great Plains. Map. A.R. Aandahl. Lincoln, Nebr. Baumberger, Rodney. 1977. South Dakota rangeland resources. Soc. for Range Manage. - Old West Regional Commission Joint Publ. Soc. Range Manage. Denver. 150 pp. Bluemle, John P. 1977, The face of North Dakota, the geologic story. N. Dak. Geol. Survey Ed. Series 11. Univ. of N.D., Grand Forks. 73 pp. Branson, Farrel A. 1985. Vegetation changes on western rangelands. Soc. Range. Manage. Range Monogr. No.2. Soc. Range Manage. Denver. 76 pp. Brown, Ray W. 1971. Distribution of plant communities in southeastern Montana Badlands. Am. MidI. Nat. 85:458-477. Clambey, Gary K. 1986. Elm-Ash-Basswood. N. Dak. Outdoors. 49:10-11. Clarke, S.E., J.A. 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29:449-460. A shorter version of this paper was published in Rangelands 10(6). |