Physiognomy and Structure: This community has a good deal of structural variation among the different sites. The tree canopy cover is thought to vary from about 25-80%. Shrubs are almost always present (Abrams 1986). The drier sites have smaller trees, less canopy cover, and less basal area than more mesic sites. On the sites that were measured at Konza Prairie, Abrams (1986) reported that this community had an average basal area of 20.5 m2/ha. The range was 13.4-31.6 m2/ha in the nine stands he analyzed in northeastern Kansas (Groups 3 and 4 in his paper). The number of trees/ha also was highly variable. There were an average of 467 stems/ha of tree species greater than 10 cm in diameter. Eight of the stands fell within a range of 207-583 stems/ha while one had 927 stems/ha.

Floristics: This community is dominated by broad-leaved deciduous trees. Quercus muehlenbergii dominates the overstory of the driest stands with Quercus macrocarpa as a subdominant. Quercus macrocarpa becomes more important in sites where conditions are more mesic until, eventually, the community grades into a forest with relatively little Quercus muehlenbergii. Ulmus spp. and Cercis canadensis can be abundant, especially as smaller individuals, and Juniperus virginiana is uncommon. The potential of Ulmus spp. to remain as an important part of this community is in doubt because of Dutch elm disease. The two most common shrubs are Cornus drummondii and Symphoricarpos orbiculatus. Celtis occidentalis and Ulmus spp. are often in the shrub layer, especially on sites that have not been burned recently. Herbaceous dominants include Schizachyrium scoparium and Panicum virgatum.

Tree canopy cover is not completely closed in this community; it may be between 25-80%. The height of dominant trees is limited on drier sites. Shrub cover varies inversely with tree canopy cover, achieving 50-60% in some of the drier stands surveyed by Abrams (1986, 1988). The high values for shrub canopy cover may be a result of the increase in fire intervals since the 1850s. Shrub canopy fell from 59.7 to 9.5% when a woodland of this type was burned in two consecutive springs (Abrams 1988).

The composition of the canopy of this community is relatively constant, being dominated by Quercus muehlenbergii and Quercus macrocarpa (average importance values of 171.2 and 64.9, respectively, at Konza Prairie), with Cercis canadensis and Ulmus spp. in varying amounts (Abrams 1986). Morus rubra is often present but does not attain a high importance. The patterns of dominance in tree species depend on site history and environmental characteristics. Quercus muehlenbergii and Quercus macrocarpa can remain the dominants in all age classes in stands that have a fairly high fire frequency. The canopy becomes more complete as fire frequency drops. On the drier sites, Ulmus spp. and Cercis canadensis are able to reproduce preferentially in the lower light environment that occurs as the canopy begins to close over. The ability of Ulmus spp. to remain in the community depends on whether Dutch elm disease affects the stand or not. On more mesic sites, different species acquire dominant status. Quercus macrocarpa remains as a dominant. Celtis occidentalis is able to reproduce in the lower light environment and eventually comes to dominant status, with lesser amounts of Ulmus spp. and Fraxinus pennsylvanica. At this point the community has changed enough to become a different forest community.

This community has a good deal of structural variation among the different sites at Konza Prairie. The tree canopy cover may vary from about 25-80%. Shrubs are almost always present (Abrams 1986). The drier sites have smaller trees, less tree canopy cover, and less basal area than more mesic sites.

Dynamics:  Drought and fire were common natural disturbances in this community type. Fire was very important in determining which species were able to survive and reproduce successfully. Fire killed or stunted the woody growth enough to maintain the relatively open canopy necessary for the dominant plants to reproduce successfully. The mean fire intervals for the period 1862-1983 in three stands studied by Abrams (1985) were 11.2, 12.6, and 19.7 years based on fire scars in the cross section of trees. This may be longer than the actual fire intervals because not all fires in a stand result in identifiable scars. Fire intervals prior to settlement in the Flint Hills of Konza were thought to be 2-3 years (Abrams 1985). This community is stable only with a regime of periodic fire (Abrams 1985). Most of the dominant trees in the stands studied by Abrams (1986) at Konza Prairie were 100-125 years old, indicating that they originated shortly after fire suppression began in the 1850s. These stands were likely on sites that had been prairie (Bragg and Hulbert 1976). However, these oaks were not regenerating well as the canopy began to close over. The seedling and sapling layers of unburned stands contained few oaks. On drier sites about 85% of the individuals were Cercis canadensis or Ulmus spp., most of the rest were Quercus muehlenbergii. On more mesic, lower slopes Celtis occidentalis and Ulmus spp. made up about 75% of the sapling and seedling stages. These data indicate that the more mesic sites will probably become dominated by Celtis occidentalis, while the drier sites will have some combination of Quercus muehlenbergii and Cercis canadensis. The presence of Dutch elm disease raises the question of whether Ulmus spp. can persist in this community.

Abrams (1988) observed the effect of prescribed burns done in two consecutive springs on a relatively closed site. Before burning, only 1% of the seedlings were Quercus macrocarpa or Quercus muehlenbergii, 87% were Ulmus spp., and 6% were Celtis occidentalis. The sapling composition was very similar to that of the seedlings except that there were no oaks. The shrub cover was 59.7%. No canopy trees died as a direct result of the burns, but the shrub layer was reduced to 9.5% cover. All of the saplings were killed by the fires. Ulmus spp. and Celtis occidentalis seedlings increased, primarily as a result of basal sprouting. The oak seedlings were eliminated. Abrams (1988) hypothesized that if the area was burned frequently over several more years the fire-sensitive Ulmus spp. and Celtis occidentalis would continue to be killed, even if they avoided fires long enough to grow to be saplings. Oak seedlings could grow enough to be resistant to subsequent fires if they occurred in microsites that were not burned for a few years. If fires were frequent enough and burned all of the woody seedlings continually then the site would eventually become a prairie.

Precipitation and temperature are quite variable. The continental climate within which this community occurs is marked by hot summers and cold winters. The average temperature was 12.8°C, with a range from -2.7° to 26.6°C during the period 1951-1980 (Abrams and Knapp 1986).