Northern Non-Acid Floodplain - PROVISIONAL
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T1B More details
- Transition T1C More details
- Transition T1D More details
- Transition T1E More details
- Restoration pathway R2A More details
- Transition T2A More details
- Restoration pathway R3A More details
- Transition T3A More details
- Transition T3B More details
- Restoration pathway R4A More details
- Restoration pathway R4B More details
- Transition T4A More details
- Transition T4B More details
- Transition T4C More details
- Transition T5A More details
- Transition T5B More details
- Restoration pathway R6A More details
- Transition T6A More details
- Transition T6B More details
- Restoration pathway R6B More details
- Transition T6C More details
- Restoration pathway R7A More details
- Restoration pathway R7B More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The pre-settlement plant community of this ecological site was largely removed more than 150 years ago, and the fertile and moist alluvial fans, bottoms, and drainageways of this site were among the first to have been converted (Hodges, 1995). There are no extant examples of that community. Early descriptions of the forests of the Loess Hills emphasized the heavy presence of cane throughout the bottoms and steep backslopes (e.g., Hilgard, 1860; Loughridge, 1888). Since dense cane growth appears to require some form of disturbance (e.g., fire and/or canopy gaps), the pre-settlement community of this site may have been much more open than what is experienced today (see Gagnon and Platt, 2008; Gagnon, 2009). Heineke (1987) suggested that the forests of the Loess Hills had an open physiognomy, which is unlike the dense, closed-canopied forests of today. The natural fertility and moisture retention of the deep non-acid soils of this site foster tremendous plant production. Without disturbance, dense woody regrowth on this site leads to closed-canopy conditions and high shade.
Following decades of land-use impacts, the plant community that returned in those areas initially set aside for protection 50 to 80 years ago (e.g., parks, natural areas, and refuges) are often comprised of a large mesophyte component in addition to a number of oak species. Cane is still an important component of the understory but its occurrence is usually represented by single stems beneath high shade and not the dense stands (brakes) that was historically reported. Without a model of the pre-settlement forest to follow, reference conditions of this site reflect conditions of maturing stands observed within public lands and/or private reserves.
Two community phases are currently recognized within the reference state. They are distinguished from one another based on the degree of successional stage (development); level or intensity of disturbance; and relative proportion of shade-tolerant vs. shade-intolerant species present in local stands.
Submodel
Description
This state is characterized by the regeneration or regrowth of a pre-existing forest stand following a major, stand-replacing disturbance. Scale of the disturbance is at the stand level and is greater than one acre in size (Johnson et al., 2009). Potential types of disturbances include catastrophic windstorms, wildfire, silvicultural clearcuts, and particularly destructive ice storms. The resulting, even-aged stand (or single-cohort) is set on a new course of development, which is highly dependent upon several critical factors including: the composition and structure of the stand prior to the disturbance; the degree or intensity of the disturbance; size and configuration of the disturbed area; and distance to seed sources.
Composition and condition of the forest stand prior to a major disturbance may dictate, in large part, future composition of the regenerating stand. Although colonization by new species is expected soon after the disturbance, many of the pre-existing overstory components are anticipated to occupy position in the new, developing stand – their presence arising mainly from stump or root sprouts, advance regeneration, and germination from the seed bank (Oliver and Larson, 1990).
Submodel
Description
Forests in this state have undergone repeated select harvests over time. Actions leading to this condition consist of removing the largest and healthiest individuals of the most desirable species and leaving low-quality trees (damaged and deformed) and undesirable species. This action, conducted repeatedly, can cause tremendous shifts in species composition and can decrease the vigor and health of the residual stand. Without implementing carefully prescribed management actions, species composition of extreme high-graded stands may remain in a highly altered condition for many decades, even after large, stand-replacing disturbances resets “successional opportunity.”
Today, this vegetation state probably represents the conditions of many forest stands throughout the distribution of this site. Local stands in which desirable species such as oaks, tuliptree, walnut, etc. were repeatedly targeted often results in sites with proportionally more hickory, maple, and beech. Stands where hickory was also targeted often support maple, hophornbeam, and disproportionate numbers of other components such as boxelder, hackberry, and sugarberry.
Submodel
Description
Two timber management phases are recognized to represent the range of management options and outcomes. The first phase focuses on the broad range of hardwoods supported on this site, and the second represents conversion to a pine monoculture (or plantation).
Submodel
Description
This state is representative of sites that have been converted to and maintained in pasture and forage cropland, typically a grass – legume mixture. For pastureland, planning or prescribing the intensity, frequency, timing, and duration of grazing can help maintain desirable forage mixtures at sufficient density and vigor (USDA-NRCS, 2010; Green et al., 2006).
This state or land use is probably the most infrequent of all management options on this site.
Submodel
Description
This state represents a return to forest conditions following the abandonment of pastureland/grassland and cropland management. The developmental stage of this state follows the “old field” condition and begins at canopy closure of the new forest stand. This initiates the stem exclusion period whereby establishment of additional canopy species becomes exceedingly difficult without active management (Oliver and Larson, 1990).
Composition of the resulting forest will vary considerably depending on the amount of time the site was previously managed; the intensity of former land use practices; the condition of the land prior to abandonment; and the source and distance of the nearest seed sources. Some pioneer species of the new stand may dominate early on but will be replaced by competitors within the community as the stand matures. Competitive interactions are intense at this stage.
Submodel
Mechanism
This pathway represents a large-scale, stand replacing disturbance, which may be caused by a catastrophic windstorm (e.g., straight-line winds, tornado), ice storm, severe fire, or a silvicultural clearcut. For this stressor to occur, most or all of the overstory must be removed or destroyed. A few residual trees may persist, but overall, the disturbance must be intensive enough, at least one acre or larger (Johnson et al., 2009), that a new, even-aged stand is created.
Mechanism
Repeated selective harvesting or high-grading of stands over time can cause shifts in species composition, structure, and overall health of affected stands. High-grading occurs when the most desirable trees of select species are repeatedly removed leaving behind inferior, low quality stems and undesirable species.
Mechanism
This pathway consists of prescribed silvicultural activities specifically designed to meet stand compositional and production objectives. Activities may include release cuttings through a combination of low and high thinning, mechanical and chemical control of competition, and artificial regeneration (i.e., planting) of sites with low oak presence. A variety of silvilcultural methods may be employed including group selection, single tree selection harvests (all classes/condition; avoid “high-grading”), or even-age management (clearcut). The final option of this pathway is the conversion of the former hardwood forest to a pine monoculture or plantation (Phase 4.2). This action requires mechanical removal of all hardwoods, site preparation, herbicide treatment of root sprouts, and planting in pine; loblolly pine should be the preferred species given the productivity of the site.
Mechanism
Actions required to convert forests to grassland or forage production include forest clearing, stump removal, herbicide application, seedbed preparation, and the establishment of desired plants.
Mechanism
Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; and preparation for crop establishment.
Mechanism
This pathway represents a return to reference conditions through natural succession, if the disturbance occurred within a reference community. Depending upon objectives and stand condition, management activities to aide recovery may include exotic species control and silvicultural treatment that benefits oak regeneration and establishment (e.g., TSI practices such as crop tree release, low thinning, and cull removal).
Mechanism
This pathway represents the development of an even-aged stand that is prescribed to meet compositional and production objectives, which may be either hardwood management or pine monoculture.
Mechanism
This pathway represents a large-scale, stand replacing disturbance, which may be caused by a catastrophic windstorm (e.g., straight-line winds, tornado), ice storm, severe fire, landslide, or a silvicultural clearcut. For this stressor to occur, most or all of the overstory must be removed or destroyed. A few residual trees may persist, but overall, the disturbance must be intensive enough, at least one acre or larger (Johnson et al., 2009), that a new, even-aged stand is created.
Mechanism
Actions include forest clearing, stump removal, herbicide application, seedbed preparation, and the establishment of desired plants.
Mechanism
Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; and preparation for cultivation or orchard establishment.
Mechanism
Natural succession over a period of time may transition a former timber-managed stand (Phase 4.1) to one supporting reference conditions. Based on observations of some reference stands, a period greater than 50 years may be required. Some question remains whether a return to reference conditions will occur in every situation, especially since some components may have been selectively culled from the stand. Management activities to aide recovery may include exotic species control and silvicultural treatment.
Mechanism
This pathway represents a large-scale, stand-initiating disturbance, which effectively removes most or all of the pre-existing overstory. Disturbances may include a catastrophic windstorm, severe wildfire, slope failure or landslide, and silvicultural management (even-aged). If the disturbance is a prescribed management action, method of harvest will depend upon current timber objectives and future stand composition and production goals.
Mechanism
Repeated selective harvesting or high-grading of stands over time can cause shifts in species composition, structure, and overall health of affected stands. High-grading occurs when the most desirable trees of select species are repeatedly removed leaving behind inferior, low quality stems and undesirable species. (Pathway pertains to Community Phase 4.1).
Mechanism
Actions include forest clearing, stump removal, herbicide application, seedbed preparation, and the establishment of desired plants.
Mechanism
Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; and preparation for cultivation or orchard establishment.
Mechanism
Abandonment of grassland/pastureland management and allowing natural succession to proceed beyond the old field stage to canopy closure of the young, developing forest stand.
Mechanism
Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; and preparation for crop establishment.
Mechanism
This pathway represents natural succession back to perceived reference conditions. The period required for this transition to take place likely varies by location and is dependent upon local site conditions. Ages extrapolated from reference stands on a few protected sites (e.g., parks, refuges, etc.) suggest that a return interval to reference conditions may require more than 50 years; some of the examined stands have been protected for at least 75 years. In some cases, a return to the reference state may not be possible without considerable management effort. That effort may involve exotic species control and the reestablishment of components considered characteristic of the reference state.
Mechanism
This pathway represents a large-scale, stand replacing disturbance, which may be caused by a catastrophic windstorm (e.g., straight-line winds, tornado), ice storm, severe fire, landslide, or a silvicultural clearcut.
Mechanism
This pathway represents prescribed management strategies for transitioning an abandoned forest state to one that meets compositional and production objectives. Managing for mixed hardwood production (Phase 4.1) may require exotic species control and general timber stand improvement practices. The final option of this pathway is the conversion of the former hardwood forest to a pine monoculture or plantation (Phase 4.2).
Mechanism
Actions include forest clearing, stump removal, herbicide application, seedbed preparation, and the establishment of desired plants.
Mechanism
Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; and preparation for cultivation.
Mechanism
Seedbed preparation and establishment of desired forage/grassland mixture.
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