Ecological dynamics
Information contained in this section was developed using historical data, professional experience, field reviews, and scientific studies. The information presented is representative of very complex vegetation communities. Key indicator plants, animals and ecological processes are described to help inform land management decisions. Plant communities will differ across the MLRA because of the naturally occurring variability in weather, soils, and aspect. The Reference Plant Community is not necessarily the management goal. The species lists are representative and are not botanical descriptions of all species occurring, or potentially occurring, on this site. They are not intended to cover every situation or the full range of conditions, species, and responses for the site.
The reference plant community is a forest dominated by an overstory of northern red oak, white oak, white ash, black walnut and sugar maple. The canopy is tall (80 to 100 feet) and well developed (80 to 100 percent closure) with great structural diversity. In the most mesic landscape positions, more shade tolerant and moisture loving species, such as basswood, coffee tree, and bitternut hickory would have been in greater abundance.
While fire-prone prairies, savannas and open woodlands surround this region, Deep Loess Protected Backslope Forests historically occurred in the most protected landscape positions on lower, steep slopes in the deeper valleys furthest from the prairie uplands and would have burned less frequently (estimated 15 to 25 years) and with lower intensity. Periodic fires would have removed some of the shade tolerant understory, but it would have quickly recovered.
Deep Loess Protected Backslope Forests would have also been subjected to occasional disturbances from wind and ice, as well as grazing by native herbivores, such as bison, elk, and deer. Wind and ice would have periodically opened the canopy up by knocking over trees or breaking substantial branches off canopy trees. Such canopy disturbances allowed more light to reach the ground and favored reproduction of the dominant oak species. Grazing by native large herbivores would have kept understory conditions more open, also creating conditions more favorable to oak reproduction.
Today, most of these communities have been cleared and converted to pasture, or have undergone repeated timber harvest and domestic grazing. Most existing occurrences have a younger (50 to 80 years) canopy layer whose composition has been altered by timber harvesting practices. A few reference states still can be found, primary on public lands. An increase in hickories over historic conditions is common. In addition, in the absence of fire, the canopy, sub-canopy and woody understory layers are better developed. The absence of periodic fire has allowed more shade-tolerant tree species, such as sugar maple, white ash, or hickories to increase in abundance.
Current domestic grazing has diminished the diversity and amount of cover of forest ground flora species, and has introduced weedy species such as gooseberry, buckbrush, poison ivy and Virginia creeper created a more open understory and increased soil compaction.
Deep Loess Protected Backslope Forests are the most productive upland timber sites in the region. Carefully planned single tree selection or the creation of small group openings can help regenerate more desirable oak species and increase vigor on the residual trees. Clear-cutting does occur and results in dense, even-aged stands of primarily oak. This may be most beneficial for existing stands whose composition has been highly altered by past management practices. However, without some thinning of the dense stands, the ground flora diversity can be shaded out and productivity of the stand may suffer.
Oak regeneration is typically problematic. Sugar maple, red elm, ironwood, hickories, grapes, pawpaw and spicebush are often dominant competitors in the understory. Maintenance of the oak component will require disturbances that will impair the cool, moist, shaded conditions, so trade-offs will have to be made carefully. Prescribed fire can play a beneficial but very limited role in the management of this ecological site.
The higher productivity of these sites makes it more challenging than on other forest sites in the region. Protected aspect forests did evolve with some fire, but their composition often reflects more closed, forested conditions, with fewer woodland ground flora species that can respond to fire. Consequently, while having protected aspects in a burn unit is acceptable, but targeting them solely for woodland restoration is not advisable.
A State and Transition Diagram follows. Detailed descriptions of each state, transition, plant community, and pathway follow the model. This model is based on available experimental research, field observations, professional consensus, and interpretations. It is likely to change as knowledge increases
Ecological Site Correlation Issues and Questions:
The Illinois NRCS state office staff has requested the Illinois map units that are unique to Illinois (e.g. Sylvan, Bold) have further field investigation. This would include the following ecological sites: F115BY003MO and F115BY043MO
The Deep Loess Backslope ecological sites (F115BY003MO, F115BY043MO) may have some overstory tree species differences related to map units on the Illinois side verses the map units on the Missouri side. Further field review is needed.
State 1
Reference
The Reference State was dominated by white oak and northern red oak. Maximum tree age was likely 150 to 300 years. Periodic disturbances from fire, wind or ice maintained the dominance of white oak and no red oak by opening up the canopy and allowing more light oak reproduction. Long disturbance-free periods allowed an increase in more shade tolerant species such as basswood and sugar maple. Two community phases are recognized in this state, with shifts between phases based on disturbance frequency.
This Reference State is rare today. Some sites have been converted to grassland (State 4). Others have been subject to repeated, high-graded timber harvest coupled with domestic livestock grazing (State 5). Fire suppression has resulted in increased canopy density, which has affected the abundance and diversity of ground flora. Many Reference sites have been managed for timber harvest, resulting in either even-age (State 2) or uneven-age (State 3) forests.
Community 1.1
Northern Red Oak – White Oak/Pawpaw/ Canadian Woodnettle – Harbinger of Spring
Figure 9. MDC Hart Creek Conservation Area, Boone County, MO
This community is the most productive upland forest in the MLRA. This forest community has a multi-tiered structure, and a canopy that is 75 to 100 feet tall with 80 to 100 percent closure. The sub-canopy and understory are well developed. An abundance of shade tolerant forest generalists, such as May apple, Christmas fern, tick trefoil and white snakeroot, cover the ground. In the absence of disturbance, more shade tolerant species increase such as sugar maple, basswood, white ash and others increase in importance and add structural diversity to the system. In addition, more shade-loving forest shrub (e.g., spicebush) and herbaceous (e.g., bloodroot) species also increase.
Forest overstory. The Overstory Species list is based on field surveys and commonly occurring species listed in Nelson (2010).
Forest understory. The Understory Species list is based on field surveys and commonly occurring species listed in Nelson (2010).
Community 1.2
Northern Red Oak – White Oak / Sugar Maple Saplings – Spicebush/ May Apple – Bloodroot
The overstory is a mixture of more shade tolerant species such as northern red oak, sugar maple, basswood, white ash and others. This forest community has a multi-tiered structure, and a canopy that is 75 to 100 feet tall with 90 to 100 percent closure. An abundance of shade tolerant forest generalists, such as May apple, Christmas fern, tick trefoil and white snakeroot, cover the ground. In addition, more shade-loving forest shrub (e.g., spicebush) and herbaceous (e.g., bloodroot) species are common.
State 2
Even-Age Managed Forest
These forests tend to be rather dense, with an under developed understory and ground flora. Thinning can increase overall tree vigor and improve understory diversity. Continual timber management, depending on the practices used, will either maintain this state, or convert the site to uneven-age (State 3) forests.
Community 2.1
White Oak – Red Oak/Flowering Dogwood/ Wild Blue Phlox
This is an even-aged forest management phase. Logging activities are removing higher volumes of white oak causing a decrease in white oak in the canopy and an increase in red oak. Large group, shelterwood or clearcut harvests create a more uniform age class structure throughout the canopy layer while also opening up the understory and allowing more sunlight to reach the forest floor.
State 3
Uneven-Age Managed Forest
Uneven-Age Managed forests resemble the Reference State. The biggest difference is tree age, most being only 50 to 90 years old. Composition is also likely altered from the reference state depending on tree selection during harvest. In addition, without a regular 15 to 20 year harvest re-entry into these stands, they will slowly increase in more shade tolerant species such as sugar maple and white oak will become less dominant.
Community 3.1
Northern Red Oak – Maple/Spicebush/ Fern
This is an uneven-aged forest management phase. Selective logging activities are removing higher volumes of white oak causing a decrease in white oak in the canopy and an increase in northern red oak and sugar maple. Densities numbers, especially more shade tolerant species, are increasing at the lower size-class levels.
State 4
Grassland
Conversion of forests to planted, non-native pasture species such as tall fescue has been common in this MLRA. Steep slopes, abundant surface fragments, low organic matter contents and soil acidity make non-native pastures challenging to maintain in a healthy, productive state on this ecological site. If grazing and active pasture management is discontinued, the site will eventually transition to State 2 (Even-Age).
Community 4.1
Tall fescue - Broomsedge/Oak Sprouts
This phase is well managed grassland, composed of non-native cool season grasses and legumes. Grazing and haying is occurring.
Community 4.2
Tall Fescue - Red Clover
This phase is well managed grassland, composed of non-native cool season grasses and legumes. Grazing and haying is occurring.
State 5
High-Graded, Grazed Forest
Forested sites subjected to repeated, high-graded timber harvests and uncontrolled domestic grazing transition to this State. This state exhibits an over-abundance of hickory and other less desirable tree species, and weedy understory species such as buckbrush, gooseberry, poison ivy and Virginia creeper. The vegetation offers little nutritional value for cattle, and excessive stocking damages tree boles, degrades understory species composition and results in soil compaction and accelerated erosion and runoff. Exclusion of livestock from sites in this state coupled with uneven-age management techniques will cause a transition to State 3 (Uneven-Age).
Community 5.1
Hickory – White Ash/Hornbeam/Buckbrush
Due to high-grade logging and uncontrolled grazing, this community phase exhibits an over-abundance of hickory and other less economically desirable tree species and weedy understory species such as buckbrush, gooseberry, poison ivy and multi-flora rose. The understory vegetation offers little nutritional value for cattle, and excessive livestock stocking damages tree boles, degrades understory species composition and results in soil compaction and accelerated erosion and runoff.
