Ecological dynamics
The information in this Ecological Site Description, including the state-and-transition model (STM), was developed based on historical data, current field data, professional experience, and a review of the scientific literature. As a result, all possible scenarios or plant species may not be included. Key indicator plant species, disturbances, and ecological processes are described to inform land management decisions.
MLRA 107A is defined by a relatively low relief landscape that experiences lower rainfall amounts and available moisture compared to other MLRAs occurring to the south and east. As a result, prairie vegetation communities dominate the uplands, while forested communities are restricted to medium and large streams (Prior 1991; Eilers and Roosa 1994; MDNR 2017a, b). Loamy Floodplain Forests form an aspect of this vegetative continuum. This ecological site occurs on floodplains adjacent to stream channels on moderately well-drained soils. Species characteristic of this ecological site consist of hydrophytic woody and herbaceous vegetation.
Flooding is the dominant disturbance factor in Loamy Floodplain Forests. Seasonal flooding occurs nearly every year, and flooding can persist up to seven days. Less frequent major and extreme floods result in shifts in the plant community, from early successional communities with small trees and saplings forming open canopies to late successional communities with large trees and closed canopies (LANDFIRE 2009).
Windthrow events, beaver activity, and periodic insect and disease outbreaks influence this site to a lesser, more localized extent (LANDFIRE 2009). Windthrow events are mostly caused from tornadoes and associated winds and generally occur in the summer months. Immediate responses to high wind events can alter forest structure and species richness or evenness, thereby impacting species diversity. Composition can also shift to one containing more early-successional species (Peterson 2000). Beaver disturbances can be highly variable across the MLRA and likely had little impact on stands less than 10 years old (LANDFIRE 2009).
Loamy Floodplain Forests have increased since pre-settlement times, occurring now in all three of the major rivers in the MLRA. However, the communities present on the landscape today have been greatly altered by significant changes in the hydrology and water quality of the watershed as well as from invasions by exotic species. Some historic forests have been converted to agricultural production land. The state-and-transition model that follows provides a detailed description of each state, community phase, pathway, and transition. This model is based on available experimental research, field observations, literature reviews, professional consensus, and interpretations.
State 1
Reference State
The reference plant community is categorized as a floodplain forest community, dominated by hydrophytic woody and herbaceous vegetation. The three community phases within the reference state are dependent on a periodic flood regime. The amount and duration of flooding alters species composition, cover, and extent. Windthrow, beaver activity, and periodic insect and disease outbreaks have more localized impacts on the reference phases, but do contribute to overall species composition, diversity, cover, and productivity.
Community Phase 1.1 Silver Maple – Eastern Cottonwood/Whitegrass – Canadian Woodnettle – Sites in this reference community phase are a closed canopy forest (up to 70 percent cover) dominated by silver maple and eastern cottonwood, with sub-dominants including green ash, American elm, common hackberry, and boxelder (Acer negundo L.). Trees are medium in size (9-21 inches DBH) and range in height from 16 to 80 feet tall (LANDFIRE 2009). Climbing vines, especially riverbank grape and common moonseed (Menispermum canadense L.), can be common. Whitegrass and Canadian woodnettle are the dominant herbaceous species, but other species that can be encountered include cutleaf coneflower (Rudbeckia laciniata L.), sweet woodreed (Cinna arundinacea L.), and Canadian clearweed (Pilea pumila (L.) A. Gray). This community phase occurs from approximately 35 to 155 years (MDNR 2005).
Community 1.1
Silver Maple - Eastern Cottonwood/Whitegrass - Canadian Woodnettle
Sites in this reference community phase are a closed canopy forest (up to 70 percent cover) dominated by silver maple and eastern cottonwood, with sub-dominants including green ash, American elm, common hackberry, and boxelder (Acer negundo L.). Trees are medium in size (9-21 inches DBH) and range in height from 16 to 80 feet tall (LANDFIRE 2009). Climbing vines, especially riverbank grape and common moonseed (Menispermum canadense L.), can be common. Whitegrass and Canadian woodnettle are the dominant herbaceous species, but other species that can be encountered include cutleaf coneflower (Rudbeckia laciniata L.), sweet woodreed (Cinna arundinacea L.), and Canadian clearweed (Pilea pumila (L.) A. Gray). This community phase occurs from approximately 35 to 155 years (MDNR 2005).
Community 1.2
American Elm - Green Ash/Black Willow
This reference community phase represents a young forest in recovery from a severe flood or wind event, reducing the overstory canopy to less than 50 percent cover (LANDFIRE 2009). American elm, green ash, and slippery elm (Ulmus rubra Muhl.) are the dominant trees, and black willow (Salix nigra L.) becomes an important component in the shrub canopy occupying recently cleared areas (Tesky 1992). Silver maple and eastern cottonwood may occur as saplings, and the ground layer is very sparse. This community phase occurs from 0 to approximately 35 years since the time of last significant disturbance (MDNR 2005).
Community 1.3
American Elm - Silver Maple/Virginia Wildrye - Canadian Honewort
This reference community phase can occur over time when the floodplain becomes higher from sediment accumulation, isolating it from the channel and the frequent flood events. The overstory canopy is mature and continuous (100 percent cover). American elm and silver maple become the dominant canopy species, with green ash an important sub-canopy species. Trees are very large (>33 inches DBH) with heights reaching 115 feet tall (LANDFIRE 2009). The understory composition begins to shift from mostly wetland species to both wetland and upland species. Understory species may include Virginia wildrye (Elymus virginicus L.), Canadian honewort (Cryptotaenia canadensis (L.) DC.), and stinging nettle (Urtica dioica L.). This community phase occurs after approximately 155 years of development and persists until an extreme flood event resets the community (MDNR 2005; LANDFIRE 2009).
Pathway 1.1A
Community 1.1 to 1.2
Major flood event
Pathway 1.2A
Community 1.2 to 1.1
Natural succession
Pathway 1.1B
Community 1.2 to 1.3
Natural succession
State 2
Hydrologically-Altered State
Agricultural tile drainage, stream channelization, and levee construction in hydrologically-connected waters has drastically changed the natural hydrologic cycle of Loamy Floodplain Forests. These alterations have resulted in higher than normal flood events. Excessive siltation from upland soil erosion and streambank erosion is deposited across this site and has caused the historic tree canopy to be killed off. This has resulted in a type conversion from the species-rich forest to a simplified silver maple-dominated state. In addition, exotic species have encroached and continuously spread, reducing native diversity and ecosystem stability (Eggers and Reed 2015).
Community Phase 2.1 Silver Maple/Reed Canarygrass – Whitegrass – This community phase represents a shift in plant community composition as a result of soil dehydration and excessive siltation. Silver maple is the dominant, sometimes only, tree species present. Willows may also occur on the site. The understory maintains some native species such as whitegrass, but conditions become suitable for the initial invasion of exotic species such as reed canarygrass (Phalaris arundinacea L.) and garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande) (MDNR 2005; Eggers and Reed 2015).
Community 2.1
Silver Maple/Reed Canrygrass - Whitegrass
Community Phase 2.1 Silver Maple/Reed Canarygrass – Whitegrass – This community phase represents a shift in plant community composition as a result of soil dehydration and excessive siltation. Silver maple is the dominant, sometimes only, tree species present. Willows may also occur on the site. The understory maintains some native species such as whitegrass, but conditions become suitable for the initial invasion of exotic species such as reed canarygrass (Phalaris arundinacea L.) and garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande) (MDNR 2005; Eggers and Reed 2015).
Community 2.2
Silver Maple/Reed Canarygrass
This community phase represents persisting changes to the natural hydrology of the watershed. The overstory canopy remains relatively unchanged, but reed canarygrass forms monotypic stands, excluding all other species (Eggers and Reed 2015).
Pathway 2.1A
Community 2.1 to 2.2
Increasing changes to hydrology, increasing sedimentation, and non-native species invasion
State 3
Forage State
The forage state arises when the site is converted to a farming system that emphasizes domestic livestock production, known as grassland agriculture. Fire suppression, periodic cultural treatments (e.g., clipping, drainage, soil amendment applications, planting new species and/or cultivars, mechanical harvesting) and grazing by domesticated livestock transition and maintain this state (USDA-NRCS 2003). Early settlers seeded non-native species, as smooth brome (Bromus inermis Leyss.) and Kentucky bluegrass (Poa pratensis L.), to help extend the grazing season (Smith 1998). Over time, as lands were continuously harvested or grazed by herds of cattle, these species were able to spread and expand across the prairie ecosystem, reducing the native species diversity and ecological function.
Community Phase 3.1 Hayfield – Sites in this community phase consist of forage plants that are planted and mechanically harvested. Mechanical harvesting removes much of the aboveground biomass and nutrients that feed the soil microorganisms (Franzluebbers et al. 2000; USDA-NRCS 2003). As a result, soil biology is reduced leading to decreases in nutrient uptake by plants, soil organic matter, and soil aggregation. Frequent biomass removal can also reduce the site’s carbon sequestration capacity (Skinner 2008).
Community 3.1
Hayfield
Sites in this community phase consist of forage plants that are planted and mechanically harvested. Mechanical harvesting removes much of the aboveground biomass and nutrients that feed the soil microorganisms (Franzluebbers et al. 2000; USDA-NRCS 2003). As a result, soil biology is reduced leading to decreases in nutrient uptake by plants, soil organic matter, and soil aggregation. Frequent biomass removal can also reduce the site’s carbon sequestration capacity (Skinner 2008).
Community 3.2
Continuous Pastured/Grazing System
This community phase is characterized by continuous grazing where domestic livestock graze a pasture for the entire season. Depending on stocking density, this can result in lower forage quality and productivity, weed invasions, and uneven pasture use. Continuous grazing can also increase the amount of bare ground and erosion and reduce soil organic matter, cation exchange capacity, water-holding capacity, and nutrient availability and retention (Bharati et al. 2002; Leake et al. 2004; Teague et al. 2011). Smooth brome, Kentucky bluegrass, and white clover (Trifolium repens L.) are common pasture species used in this phase. Their tolerance to continuous grazing has allowed these species to dominate, sometimes completely excluding the native vegetation.
Community 3.3
Rest-Rotation Pastured Grazing System
This community phase is characterized by rotational grazing where the pasture has been subdivided into several smaller paddocks. Through the development of a grazing plan, livestock utilize one or a few paddocks, while the remaining area is rested allowing plants to restore vigor and energy reserves, deepen root systems, develop seeds, as well as allow seedling establishment (Undersander et al. 2002; USDA-NRCS 2003). Rest-rotation pastured grazing systems include deferred rotation, rest rotation, high intensity – low frequency, and short duration methods. Vegetation is generally more diverse and can include orchardgrass (Dactylis glomerata L.), timothy (Phleum pretense L.), red clover (Trifolium pratense L.), and alfalfa (Medicago sativa L.). The addition of native prairie species can further bolster plant diversity and, in turn, soil function. This community phase promotes numerous ecosystem benefits including increasing biodiversity, preventing soil erosion, maintaining and enhancing soil quality, sequestering atmospheric carbon, and improving water yield and quality (USDA-NRCS 2003).
Pathway 3.1A
Community 3.1 to 3.2
Mechanical harvesting is replaced with domestic livestock and continuous grazing
Pathway 3.2A
Community 3.2 to 3.1
Tillage, forage crop planting and mechanical harvesting replace grazing
Pathway 3.2B
Community 3.2 to 3.3
Implementation of rest-rotational grazing
Pathway 3.3B
Community 3.3 to 3.1
Tillage, forage crop planting and mechanical harvesting replace grazing
Pathway 3.3A
Community 3.3 to 3.2
Implementation of continuous grazing
State 4
Cropland State
The Midwest is well-known for its highly-productive agricultural soils, and as a result, much of the MLRA has been converted to cropland, including portions of this ecological site. The continuous use of tillage, row-crop planting, and chemicals (i.e., herbicides, fertilizers, etc.) has effectively eliminated the reference community and many of its natural ecological functions in favor of crop production. Corn (Zea mays L.) and soybeans (Glycine max (L.) Merr.) are the dominant crops for the site. These areas are likely to remain in crop production for the foreseeable future.
Community 4.1
Conventional Tillage Field
Sites in this community phase typically consist of monoculture row-cropping maintained by conventional tillage practices. They are cropped in either continuous corn or corn-soybean rotations. The frequent use of deep tillage, low crop diversity, and bare soil conditions during the non-growing season negatively impacts soil health. Under these practices, soil aggregation is reduced or destroyed, soil organic matter is reduced, erosion and runoff are increased, and infiltration is decreased, which can ultimately lead to undesirable changes in the hydrology of the watershed (Tomer et al. 2005).
Community 4.2
Conservation Tillage Field
This community phase is characterized by rotational crop production that utilizes various conservation tillage methods to promote soil health and reduce erosion. Conservation tillage methods include strip-till, ridge-till, vertical-till, or no-till planting systems. Strip-till keeps seedbed preparation to narrow bands less than one-third the width of the row where crop residue and soil consolidation are left undisturbed in-between seedbed areas. Strip-till planting may be completed in the fall and nutrient application either occurs simultaneously or at the time of planting. Ridge-till uses specialized equipment to create ridges in the seedbed and vegetative residue is left on the surface in between the ridges. Weeds are controlled with herbicides and/or cultivation, seedbed ridges are rebuilt during cultivation, and soils are left undisturbed from harvest to planting. Vertical-till systems employ machinery that lightly tills the soil and cuts up crop residue, mixing some of the residue into the top few inches of the soil while leaving a large portion on the surface. No-till management is the most conservative, disturbing soils only at the time of planting and fertilizer application. Compared to conventional tillage systems, conservation tillage methods can reduce soil erosion, increase organic matter and water availability, improve water quality, and reduce soil compaction.
Community 4.3
Conservation Tillage with Cover Crop Field
This condition applies conservation tillage methods as described above as well as adds cover crop practices. Cover crops typically include nitrogen-fixing species (e.g., legumes), small grains (e.g., rye, wheat, oats), or forage covers (e.g., turnips, radishes, rapeseed). The addition of cover crops not only adds plant diversity but also promotes soil health by reducing soil erosion, limiting nitrogen leaching, suppressing weeds, increasing soil organic matter, and improving the overall soil. In the case of small grain cover crops, surface cover and water infiltration are increased, while forage covers can be used to graze livestock or support local wildlife. Of the three community phases for this state, this phase promotes the greatest soil sustainability and improves ecological functioning within a cropland system.
Pathway 4.1A
Community 4.1 to 4.2
Less tillage, residue management
Pathway 4.1B
Community 4.1 to 4.3
Less tillage, residue management and implementation of cover cropping
Pathway 4.2A
Community 4.2 to 4.1
Intensive tillage, remove residue, and re-initiate monoculture row cropping
Pathway 4.2B
Community 4.2 to 4.3
Implementation of cover cropping
Pathway 4.3B
Community 4.3 to 4.1
Intensive tillage, remove residue, and re-initiate monoculture row cropping
Pathway 4.3A
Community 4.3 to 4.2
Remove cover cropping
State 5
Reconstructed Floodplain Forest State
The combination of natural and anthropogenic disturbances occurring today has resulted in numerous ecosystem health issues, and restoration back to the historic reference state may not be possible. Many natural forest communities are being stressed by non-native diseases and pests, habitat fragmentation, permanent changes in hydrologic regimes, and overabundant deer populations on top of naturally-occurring disturbances (severe weather and native pests) (Flickinger 2010). However, these habitats provide multiple ecosystem services including carbon sequestration; clean air and water; soil conservation; biodiversity support; wildlife habitat; as well as a variety of cultural activities (e.g., hiking, hunting) (Millennium Ecosystem Assessment 2005; Flickinger 2010). Therefore, conservation of floodplain forests should still be pursued. Habitat reconstructions are an important tool for repairing natural ecological functioning and providing habitat protection for numerous species of Loamy Floodplain Forests. Therefore, ecological restoration should aim to aid the recovery of degraded, damaged, or destroyed ecosystems. A successful restoration will have the ability to structurally and functionally sustain itself, demonstrate resilience to the ranges of stress and disturbance, and create and maintain positive biotic and abiotic interactions (SER 2002). The reconstructed forest state is the result of a long-term commitment involving a multi-step, adaptive management process.
Community 5.1
Early Successional Reconstructed Forest
This community phase represents the early community assembly from forest reconstruction. It is highly dependent on the current condition of the site based on past and current land management actions, invasive species, and proximity to land populated with non-native pests and diseases. Therefore, no two sites will have the same early successional composition. Technical forestry assistance should be sought to develop suitable conservation management plans.
Community 5.2
Late Successional Reconstructed Forest
Appropriately timed management practices (e.g. forest stand improvement, continuing integrated pest management) applied to the early successional community phase can help increase the stand maturity, pushing the site into a late successional community phase over time. A late successional reconstructed forest will have an uneven-aged, closed canopy and a well-developed understory.
Pathway 5.1A
Community 5.1 to 5.2
Timber stand improvement practices implemented
Pathway 5.2A
Community 5.2 to 5.1
Setback from extreme weather event or improper timing of management actions
Transition T1A
State 1 to 2
Changes to natural hydroperiod and/or land abandonment
Transition T1B
State 1 to 3
Cultural treatments are implemented to increase forage quality and yield
Transition T1C
State 1 to 4
Agricultural conversion via tillage, seeding and non-selective herbicide
Transition T2A
State 2 to 3
Cultural treatments are implemented to increase forage quality and yield
Transition T2B
State 2 to 4
Agricultural conversion via tillage, seeding, and non-selective herbicide
Transition R2A
State 2 to 5
Site preparation, tree planting, repair hydrology, non-native species control
Restoration pathway T3A
State 3 to 2
Changes to natural hydroperiod and/or land abandonment
Transition T3B
State 3 to 4
Agricultural conversion via tillage, seeding, and non-selective herbicide
Transition R3A
State 3 to 5
Site preparation, tree planting, repair hydrology, non-native species control
Restoration pathway R4A
State 4 to 2
Site preparation, tree planting, repair hydrology, non-native species control
Restoration pathway T4B
State 4 to 3
Cultural treatments are implemented to increase forage quality and yield
Transition R4A
State 4 to 5
Site preparation, tree planting, repair hydrology, non-native species control
Restoration pathway T5A
State 5 to 2
Changes to natural hydroperiod and/or land abandonment
Restoration pathway T5B
State 5 to 3
Cultural treatments are implemented to increase forage quality and yield
Restoration pathway T5C
State 5 to 4
Agricultural conversion via tillage, seeding, and non-selective herbicide
