Northern Moderately Wet Loess Terrace - PROVISIONAL

Description

The somewhat poorly and poorly drained soils occurring on level to nearly level terraces and valleys of the Loess Plains are situated in such close association that it is difficult to distinguish their respective influences on natural vegetation. This is especially confounding today due to nearly two centuries of continual manipulation and alteration of these systems. It is hypothesized that the somewhat poorly drained soils of this site support a slightly drier association of plants due to the soils’ slightly higher position and slope gradient relative to the lower poorly drained soils. However, this perceived vegetation difference has not been substantiated or definitively determined in the field. In the Western Lowlands of eastern Arkansas, a very similar pattern occurs, and it has been hypothesized that Calloway soils (also correlated to this provisional site) of that region produce an association consisting mainly of upland hardwoods (interpretation and adoption from Klimas et al., 2012). LANDFIRE (2009) and NatureServe (2009) also recognize a wet and drier versions of flatwoods for the Loess Plains, which is construed to correspond with the Northern Wet Loess Terrace and Northern Moderately Wet Loess Terrace ecological sites, respectively. Adoption of their system suggests that the dominant components of this site consist of a drier association of oaks with hickory as important associates (LANDFIRE, 2009).

A single community phase is recognized for representing the range of species occurring on this site. As additional information becomes available, revisions to this site may warrant significant changes. At a minimum, a new site will be developed for areas to the south in Mississippi where loblolly and shortleaf pine enters the community as components.

Of concern, this site has incurred tremendous alteration due to seasonal wetness issues. Any attempt to reestablish perceived reference conditions of a stand or a local site must first restore the natural hydrology of that site, if ditching or drainage structures had been constructed. If local hydrology is not restored, management may improve stand structure and even composition to a degree, but the site, overall, will remain in an altered state relative to reference conditions. Retaining drainage structures will directly influence the types of vegetation that colonize the site, which may be entirely different than reference conditions.

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Description

Agriculture production is the dominant land use activity on this site, today, although production is somewhat limited due to seasonal wetness. Many areas in production have some form of drainage structures established due to seasonal saturation of the soil surface.

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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). Overgrazed pastures can lead to soil compaction and numerous bare spots, which may then become focal points of colonization by undesirable plants or weeds. Soils exhibiting the core concepts of this site have a pronounced period of wetness followed by droughty conditions. Limitations may pertain mainly to periods of extreme wetness.

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). Because of the limitations of this site, grazing may be limited to small intervals within the appropriate season(s). It is strongly advised that consultation with State Grazing Land Specialists and District Conservationists at local NRCS Service Centers be sought when assistance is needed in developing management recommendations or prescribed grazing practices on this site.

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Description

This state represents a broad range of management objectives, options, and stand conditions including woodlots allowed to grow or revert naturally; repeated single-tree harvests (often high-graded); carefully prescribed treatments; and conversion to a monoculture or single-species stand.

Various management or silvicultural methods can lead to very different structural and compositional results. For prescribed management options, methods are diverse, which include even-aged (e.g., clearcut and shelterwood) and uneven-aged (single tree, diameter-limit, basal area, group selection, etc.) approaches. Included within these approaches is an option to use disturbance mechanisms (e.g., fire, TSI, etc.) to reduce competition and achieve maximum growth potential of the desired species. Inherently, these various approaches result in different community or “management phases” and possibly alternate states. The decision to represent these varying approaches and management results into a single state and phase at this time hinges on the need for additional information in order to formulate definitive pathways, management actions, and community responses. Forthcoming inventories of this site will provide more detail on this state and associated management phases.

Of warning, there are some timber management limitations due to alternating seasonal wetness and dryness; the latter often rendering the soil hard and compact and droughty. These collective impacts could lead to high seedling mortality and/or low productivity of individual trees.

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Description

This alternative state is included to represent the range or breadth of conservation actions that may be implemented and established should other land uses be discontinued within a given location. Several actions may be chosen including the standard of establishing: native warm season grasses; suitable forbs for pollinators; select native trees to manage for forest or woodland conditions. If at all possible, the herbaceous species established should be derived from the “wild types” (genetic stock) from the Loess Plains or from adjoining ecoregions. This action would help preserve the unique genetic material from the area and would help to reintroduce the native herbaceous taxa back into a portion of their former range.

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