The Saline River just before it enters Wilson Reservoir, Russell Co. The bluffs are Dakota Sandstone outcrops.
Photo courtesy of Robert R. Patterson
In classifying assemblages of plants and animals one must take into consideration the past history of the area and effects of humans. In the geologic past there was not always the same distribution of prairies and forests as today. Kansas, at various times in its history, has been completely covered by forests, and even glaciers and their outwash plains. Nor are the conditions the same now as they were before humans modified the wilderness. European immigrants recognized the usefulness of prairies for growing grains or for grazing, and woodlands for shade and windbreaks, provided avenues for western expansion of woodland species onto the prairie.
Most research on prairie and woodland has been pursued after virgin prairie and forests, and the larger mammals, have disappeared. Study of relict populations of plants and animals preserved in enclosed cemeteries and along some railroad rights-of way has supplied us with information that helps us interpret the original conditions in Kansas. This information also helps to interpret the complex and diverse changes created by humans.
Shelford (1963) proposed a system of classifying plant and animal assemblages for North America. He divided Kansas into two contrasting ecological communities consisting of grasslands in the west and temperate deciduous forests in the east, each having its own particular life forms and associated animals, and both ultimately controlled by climate. There are other systems of classifying natural communities, but Shelford's "Biome System" provides a dynamic interrelationship between all the factors of the community and the environment. In Shelford's terminology a community consists of a group of plants and animals that are coacting with one another and at the same time are reacting with the non-living elements of the habitat. The interaction of the habitat and community is the ecosystem. Dominant animals and plants have control over the ecosystem. Dominant animals and plants have control over the community and range throughout the Biome, Whereas influents modify abundance, but do not control the community. Major influents are generally large animals and minor influents are small. Some other terms used to explain the Biome system are: ecotone, a transitional strip separating two communities; aspection, the seasonal changes during the year; edaphic, referring to local conditions of soil moisture or topography; climax, the ultimate development of a community controlled by climate; and seral stages, succession of different kinds of plant and animals from the pioneer stage to climax.
The original forests in eastern Kansas were remnants of a more extensive and continuous forest of earlier geological ages and had counterparts in Europe, eastern Asia, and the western United States. Oak and hickory were dominant trees, and the wild turkey, deer, and black bear were dominant animals in the deciduous forests in Kansas.
Ecologically a forest is an ecosystem which is much more than the sum of its individual parts. The canopy of trees, for example, is formed from broad green leaves which supply constant shade, thus reducing temperature, evaporation, wind, and increasing humidity, whereas a single tree standing alone does not have this capacity. The forest has an understory of small trees and shrubs and a floor covered with a dense layer of dead leaves, fallen trees in various stages of decay, fungi, insects, worms, and organic matter, all integral parts of the forest community and all interacting in various ways. The decaying leaves also make soils more porous and reduce runoff by absorbing and holding water, and then slowly discharging it into drainage systems. There is a distinct seasonal pattern controlled by changes of temperature and light, each bringing about a change in patterns of community activity and composition. In winter, leaves are off trees and some animals hibernate. Summer birds are replaced by winter birds and feeding activity is adjusted to snow and cold weather. In spring, mammals and insects come out of hibernation and new plant growth begins. Migrating birds move through the forests and seeds become available. In summer, birds and mammals rear young, and later gather and feed on ripening fruits and nuts. In autumn, leaves change color, fall from trees, and other vegetation dies. Some mammals hibernate and many insects burrow deep in the ground. In addition to seasonal changes, there are daily rhythms inherent in an ecosystem. Most rhythms are associated with sunlight, such as manufacture of food by plants in the daytime and foraging activity or resting of animals at night or twilight.
Deciduous forests are dependent upon a humid continental climate. The growing season extends from the last frost of mid April to mid October. Three fourths of the annual rainfall occurs during this time, providing sufficient moisture for trees to grow on slopes as well as in valleys. Exclusive of winter (December to February), forests receive approximately 30 inches of rain, but on occasion more than 50 inches, which may produce severe flooding. The temperature seldom goes above 100¡F or below 0¡F for extended periods of time. Fluctuations in daily extremes occur more often in winter when the weather is dominated by shifting air masses. Warm air may flow from the south one day, while the next day cold air may move in from the north. A moderate amount of snow falls in winter, but ordinarily remains on the ground only short periods of time. However, in some years snow forms a protective covering for small mammals throughout the winter. Some winters are relatively mild, while others are extremely cold and windy, though always less so than on the grasslands to the west.
The occurrence of mammals in forests varies with the density and kinds of trees. Cliffs and rocky outcrops or streams within the forest also provide specific ecological niches for some mammals. Some of the larger mammals that have become extirpated because of forest reduction or hunting pressure are bison, mountain lion, gray wolf, red wolf, wapiti, and black bear. Mammals that still range throughout the climax and seral stages are white-tailed deer, gay fox, red fox, raccoon, Virginia opossum, eastern chipmunk, southern flying squirrel, woodchuck, white-footed mouse, woodland vole, southern short-tailed shrew, fox squirrel, and bobcat, though few mammals develop large populations in forests.
The grasslands-deciduous forest ecotone is a transition or overlapping of forest and grassland in a narrow zone occupied by a community of plants and animals that is different from either the forest or grasslands. These forest edge communities, on a long range basis, constantly fluctuate in position according to changes in climate-westward in periods of increased rain and eastward during periods of drought. There is usually a greater density and variety of plants and animals in the ecotone than in either the forests or grasslands, and some species are found only in ecotones. Many kinds of mammals seek the ecotone at one time or another; for example, bison and wapiti for feeding, shelter and bedding, where they engage in considerable trampling and grazing of shrubs. The meadow jumping mouse lives at the forest edge as does the Franklin's ground squirrel. Although the coyote favors more open places, it commonly uses the forest edge for hunting.
| An extension of deciduous forests are the forests and woodlands dominated by cottonwoods, willows, and sycamores that border river courses, marshes, and lakes within the deciduous forest biome in eastern Kansas, and extend westward into the grasslands. These forests are widely distributed and represent a stage that is controlled by local conditions of moisture and periodic flooding, never reaching a stable climax. Boxelders, elm, maples, and hackberry are associated with the dominant trees and provide considerable shade to the riparian community. At the same time, they are capable of surviving in the shade of dominant trees. The major rivers in Kansas occupy low, flat valleys. | The Saline River just before it enters Wilson Reservoir, Russell Co. The bluffs are Dakota Sandstone outcrops. |
The active flood plain consists of extensive sand bars and steep river banks occupying the narrow central part of a valley where flooding occurs periodically after heavy rains. This flood plain may move in meanders from one side of the valley to the other and can erase all other features in the valley. Existence of forest communities is precarious in this active flood plain. Older flood plains above the active plains are intermediate between them and more stable terraces above. In the early days, trees grew extensively on all parts of the river valley. The surface of flood plains is topographically irregular, having remnants of older meanders and erosional scars from infrequent large floods. Because of it irregularities it supports numerous ponds and associated aquatic communities that include beavers, muskrats, mink, and raccoons. In early times these older flood plains were reported to have grasses and marsh vegetation several meters in height. The older upper terraces are flat and subjected to flooding only during periods of unusually high water.
Frequently, local sand dunes, occasionally extensive, develop from braided river channels, especially during the low waters in late summer, and may be found at various levels above and beyond the riparian community, either as active sand dunes, or as areas stabilized by vegetation. Certain mammals find optimal refuge in these sandy communities. Most of the larger prairie mammals use the riparian community for shelter, resting, and feeding. Gray foxes, squirrels and woodland voles are good examples of mammals extending their ranges to the west along corridors of forests associated with rivers and streams.
The Kansas prairie is part of the largest biome in North America. It is defined by Shelford (1963) as the Needlegrass-Pronghorn-Grama Grass Biome which extends from Canada to the Gulf of Mexico in Texas, and from an abrupt contact with the deciduous forest of the east to the base of the Rocky Mountains and beyond. It is in sharp contrast to the riparian forest communities of the river valleys which penetrate it, and is a complex ecosystem of plants, mammals, birds, reptiles, amphibians, insects, and other animals. Grasslands have a heritage of millions of years of evolutionary history and maintained a dynamic balance until the inroads of European immigrants who, in a very short time, almost completely changed the original biome by excessive grazing, irrigation, and by permitting range extensions of certain kinds of forest animals. Unless people are willing to set aside adequate areas for its protection, the native grassland biome will disappear.
| Some open corridors and savannas extending east through the deciduous forests may have been formed in response to climatic changes following the retreat of continental glaciers, and subsequently were maintained by the grazing bison. Grasslands are ecological equivalents of the veldt of South Africa, pampas of South America, and the steppes of Russia; in fact, they occur on all continents except Antarctica. They are characterized by dominant perennial grasses, of a variety of greens in spring and summer, and yellow-brown to reddish-purple in autumn and winter. Colorful flowers, especially legumes and composites, bloom seasonally. Originally, the prairies has numerous large grazing mammals and burrowing mammals, giving the grasslands a special life form. Fire, either from natural causes such as lightning, or else set deliberately by humans as a means of driving game, has helped maintain the life form of grasslands. |  Controlled burn on Univ. of Kansas Prairie area. |
The grasslands have a greater climatic range than the deciduous forests, with high summer and low winter temperatures, strong daily winds, high rates of evaporation, and intense periods of drought. Different grassland associations in Kansas occur along a gradient of high rainfall in the east decreasing to low rainfall in the west. The tall-grass association of big bluestem, Indian grass, slough grass, and switchgrass, some of them sod-forming and growing to 12 feet high, grows in humid eastern Kansas where annual rainfall averages 35 inches and exceeds annual evaporation. The mid-grass association of both sod and bunch grass includes dropseed, Indian rice, June grass, little bluestem, needlegrass, western wheatgrass and others, and extends west to near the 100th meridian there rain averages 26 inches. The short-grass association includes blue grama, buffalo grass, and other grama grasses growing in height up to 1 1/2 feet, and extends west to the Rocky Mountains where the rainfall is less than 19 inches on the average. Some grasses have their origins in the cold climates of the north and start growing early in spring, aestivate in the hot part of the summer and then begin growing again in the cooler part of autumn, whereas grasses that have their origins in the south start growing later in spring, and continue to grow throughout summer and fall.
Grassland soils are deep and fertile with great amounts of humus and organic material suitable for deep penetration of grass roots (up to six feet) which permit survival during drought periods. These soils allow easy and extensive burrowing by many mammals, especially gophers, prairie dogs, ground squirrels, kangaroo rats, pocket mice and moles, and predators such as badgers, swift foxes and skunks that enlarge the subterranean corridors in pursuit of their prey, or when preparing their own dens. Kangaroo rats and pocket mice also dig extensively into more friable and sandy solid. Soils thus excavated are brought to the surface and spread out on the grasslands as new sources of nutrients for growth of plants and as a suitable bed for germinating seeds. Trampling by larger mammals helps force new seeds into the ground. Bison helped the soils by making trails during migration, and in maintaining dusting wallows. Their dung added to the fertility of the ground and provided microhabitats for many of the important ground beetles and other prairie insects. Along with mule deer, wapiti, bison and pronghorns, the grazing of prairie dogs, rabbits, other small rodents and grasshoppers helped maintain the prairie. Rocky outcrops and steep-walled canyons influence prairie by providing special ecological niches for mammals. These sites are favorable for woodrat nests, and as roosting sites for the small-footed myotis. The principal life habit of most small mammals on the prairie is burrowing, and they live underground during the hottest part of the day. At night they emerge and the prairie becomes a "land of a thousand eyes."
Larger gregarious mammals and some small mammals have a cursorial or swift running life habit that permits them to escape from predators. Vision is well developed and has replaced the secretive habits associated with forest dwellers. Some mammals periodically leap above the prairie vegetation to survey the country for potential danger. Ground squirrels and prairie dogs stand upright on mound of dirt excavated from burrows to gain a vantage point, and remove most of the vegetation around the burrows or colony for better view of potential predators. Many animals use burrows excavated by other animals, especially after the burrow has been abandoned by its original occupant. Some burrows are shared by burrowing owls, snakes, lizards, insects, and other mammals. Woodrats have been known to share their nests with several kinds of small mammals. Social groupings of herds and colonies provide additional benefit by ensuring that any warning call will alert all members of the group.
Animals are much alike in mixed- and tall-grass associations, but some faunal changes are evident to the west. Some mammals that are found only in the short-grass association are: desert cottontail, silky pocket mouse, spotted ground squirrel, and, formerly, the white-tailed jack rabbit. Mammals occurring in both short-grass and mid-grass associations are: black-footed ferret, black-tailed prairie dog, northern grasshopper mouse, plains pocket mouse, pronghorn, southern plains woodrat, and swift fox. The important mammals of the grassland biome are, or were, the badger, bison, pronghorn, gray wolf, and jack rabbits. The wapiti and deer seek cover in riparian communities, but graze in the open. These and other mammals also occur in forest and other biomes; the longtailed weasel, gray wolf and bison are good examples of this ability to live under conditions found in several biomes.