St. Francis - Sandy Natural Levee and Meander Scroll Forest

Description

Removal of the historic natural communities of this site occurred long before thorough studies and investigations were conducted. Furthermore, the hydroperiod and drainage patterns of the landscape have since been dramatically altered. Great variability is likely to occur throughout the distribution of this ecological site. Local soils and hydrologic regimes will have been influenced by the environment they occur within, in addition to former land use histories. Such complexity across the area will likely be reflected in much variability in vegetation composition and structure of local stands (Stanturf et al., 2001).

Accordingly, reference conditions for this site have yet to be confirmed, but they are perceived to consist of mature forest stands that support a diverse mix of southern bottomland hardwoods adapted to the moderately well to excessively drained soils of this site. Once assigned or identified, the reference community will not represent the pre-settlement forest community, but it should identify an assemblage of naturally occurring species that reflects and contributes to regional biodiversity and local forest ecology. Implicated in the latter is that the “local” geomorphic features and drainage patterns of this soil-site environment should not have been drastically altered or removed (e.g., land leveled).

The current state and transition model does not have a return or transition pathway from the altered states back to reference conditions. Former land uses (alternate states) that result in soil compaction (increased bulk densities), lower soil organic matter content, altered fertility, and smaller available rooting volume can reduce forest site productivity by 10 to 20 percent, if not more, for some species (Groninger et al., 1999) and may result in high seedling mortality. Attempts to establish reference conditions under these soil-site constraints could result in poor establishment and response, colonization by undesirable taxa, or failure. These soil-site impacts, however, can be ameliorated through various “afforestation” techniques such as plow pan breakup (subsoil or deep plowing), fertilization, and fallowing fields before stand establishment (Emile Gardiner, USFS Research Forester, personal communication). State 5 (Forest Recovery) is representative of forest establishment and growth on locations where soil compaction and reduction of nutrients have occurred. Once a previously affected location has recovered its site potential, transition to the reference state may be possible. Realistically, it may not always be possible to return to a “perceived” reference state from a former altered condition. While planting and establishing trees appropriate for a site may be possible, achieving restoration of the understory and other system functions present challenges that may never be realized (Stanturf et al., 2001; Flinn and Vellend, 2005). That potential transition is still under review and is currently not shown or addressed in the state and transition model.

Submodel

Description

This state is representative of the dominant land use activity within the MLRA, agriculture production. The types of crops grown on this site will likely vary by soils and location. Some areas may remain “idle” or in a natural state due to extreme droughtiness. For those areas suitable for production, small grains such as grain sorghum (Sorghum bicolor) and wheat (Triticum aestivum) may be grown (USDA-SCS, 1990; USDA-NRCS, 2006b). It is possible that in areas with greater moisture additional crops may be suitable. Soil components of the Steele and Beulah series may support additional crops such as soybeans, cotton, and corn (Soil Survey Staff), but these are likely to occur as inclusions or within a much larger, wetter soil-site environment.

The soils of this site have varying suitability for agriculture production. In general, Crevasse soils are poorly suited to row crops due to droughtiness. Beulah soils are generally productive and well suited for cropland if moisture is plentiful, but because of the low available water capacity, crops can be negatively impacted during dry periods. Bruno soils are typically considered poorly suited for cropland due to rapid permeability and very low to low available water capacity. Collectively, tilth of these soils is good with a surface layer that is very friable and easily tilled over a wide range of moisture content (USDA-SCS, 1990; USDA-NRCS, 2006b). Management concerns are largely centered on water management, availability, and need; erosion (including wind erosion); low to moderate organic matter content; crusting and packing following heavy rain; and the potential for plow pan development and soil compaction, particularly on Beulah and Steele soils. Each of these factors could affect yields or impede optimum operation. Management measures to ameliorate some of these issues may include implementing a water management strategy, a conservation tillage or management system, and subsoiling to breakup plow pans (USDA-NRCS, 2006b). Major components that producers generally develop and plan are proper selection of crop cultivar, pest control, cropping system, tillage methods, nutrient management, and water management (Snipes et al., 2005). Key practices of some cropping systems often include two or more crops grown in a multiyear rotation, which has been documented to disrupt pest cycles. Leaving crop residue on the surface can help to maintain tilth, fertility, and organic matter content – all critical elements of soil quality and health. For monoculture cropping systems, the implementation of well-designed pest and nutrient management systems are imperative (Pringle et al., 2017). (For assistance, interested parties are advised to visit their local NRCS Field Office.)

Three separate management phases comprise this state: Conservation Management (3.1), Transitional Conservation Management (3.2), and Conventional Management (3.3). The three phases consist of varying tillage methods and approaches to soil health management systems.

Submodel

Description

This gently sloping ecological site typically adjoins nearly level to level landscapes. It is bordered by soils of varying textures and drainage characteristics. Accordingly, inconsistencies in wetness, ease of operation, and production or yields may occur across a cropped location. An increasingly common practice on this site consists of land forming or leveling surface irregularities into a predetermined and engineered, uniform slope. This practice removes the drier and higher features of this site, which are then used to fill wetter and lower positions (e.g., depressions or swales) across the targeted area. Advantages of land leveling may include reduced hazards of erosion and runoff rates, improved surface drainage, and enhanced distribution and conservation of irrigation water. Disadvantages of the practice is a churning of various surface and subsurface materials (former soil horizons) that no longer occur in a predictable or regular pattern. Organic matter content in the surface layer is generally low, and the surface tends to crust and pack after heavy rains (USDA-NRCS, 2006b). One potential hazard that appears to be emerging in some areas is an effective management of surface water runoff. As both irrigated and stormwater runs off leveled fields at uniform rates, surface water tends to collect cumulatively and simultaneously, which places tremendous demands on local drainage networks. Without “in field” structures (natural or artificial) to stagger runoff, the downslope (or lower) ends of some fields tend to back flood thereby contributing to more flooding overall in local watersheds (personal observations).

Immediately following land leveling, the constituent elements of soil health are likely to be absent. In some areas, producers have initiated practices such as applying organic residues (e.g., poultry litter) or growing rice crops for one to two years to rapidly boost fertility and introduce organic matter (via rice biomass) in the surface layer. Over time, the full complement of the management (or community) phases of State 2 may be possible on land leveled fields. They are not repeated or indicated here.

Currently, this state serves as an endpoint in the state and transition model because the ability to predict vegetation response when transitioning to a different state is no longer possible without soil-site investigations for each area of interest. The former soils of this ecological site, including surface and subsurface horizons, will have been redistributed as particles among other former soils.

Submodel

Description

This state is representative of areas that have been converted to and maintained in pasture or grassland. These sandy soils may be best suited to deep rooted perennial grasses, cool season reseeding legumes, and cool season annual forage plants. They may not be suited to tall fescue (Schedonorus arundinaceus) and dallisgrass (Paspalum dilatatum). Available water capacity is very low to low (USDA-SCS, 1990), which contributes to low forage production. Areas having strongly to moderately acid reactions may benefit from lime applications. However, reactions of Crevasse soils generally range from moderately acid to moderately alkaline; the need for lime may be location specific. Locations with a pH above 6.5 may be further limiting for some forage species like bahiagrass (Paspalum notatum), which generally responds poorly on neutral to alkaline soils (Houck, 2009).

Given that this ecological site adjoins lower, wetter sites, some forage operations may utilize the higher elevations of this site as a protected area. This site may be suitable for the storage of harvested forage or holding of livestock when wet or flooded conditions occur on lower areas.

Establishing an effective pasture management program can help minimize degradation of the site and assist in maintaining growth of desired forage. An effective pasture management program includes selecting well-adapted grass and/or legume species that will grow and establish rapidly; maintaining proper soil pH and fertility levels; using controlled grazing practices; mowing at proper timing and stage of maturity; allowing new seedings to become well established before use; and renovating pastures when needed (Rhodes et al., 2005; Green et al., 2006).

This state consists of four community phases that represent a range of forage management options and pasture and hayland condition scenarios. Options range from establishing a forage monoculture for haying to a broad mixture of forage species for production and grazing. It is strongly advised that consultation with local NRCS Service Centers be sought when assistance is needed in developing management recommendations or prescribed grazing practices.

Submodel

Description

This state is representative of forest recovery in areas that were once under former intensive land use such as long-term row crop cultivation. Characteristics that distinguish this state from other forest states on this site include a suite of soil-site properties that reportedly affect tree growth such as higher soil bulk density due to compaction, presence of a plow pan, lower organic matter content, and reduced fertility (Baker and Broadfoot, 1979; Groninger et al., 1999). Two community phases are provisionally recognized for this state. Community phase 6.1 represents natural colonization of tree and shrub species without management. Community phase 6.2 is representative of intentional forest establishment by artificial regeneration or planting.

For Community Phase 6.2, determining the objectives and goals of the future stand is imperative to increase the probability of successful establishment and production of the afforested area. These decisions will ultimately determine the species to be established, preparation requirements, planting density, and post-planting operations (e.g., competitor control, future improvement cuttings and thinnings, regeneration methods, and overall stand health). Since each area targeted for afforestation may have unique or different land use histories, having a clear understanding of the soil-site conditions is essential. Some areas may necessitate a series of soil improvement actions prior to planting. These actions may include subsoiling or deep plowing to breakup plow pans and fertilizing the targeted area. An additional option is to allow the area to undergo fallowing for a predetermined period (Community Phase 6.1) to potentially increase soil organic matter content, enhance soil aggregate stability, increase soil biological activity, and improve water holding capacity and infiltration rates. Controlling competing vegetation (chemical and/or mechanical treatment) will most likely be critical. Post-planting operations and maintenance of the stand can enhance survival, future development, and achieve goals and objectives (see Gardiner et al., 2002).

Finding the appropriate approach for a given environment necessitates close consultation with trained, experienced, and knowledgeable forestry professionals. If there is a desire to proceed with this state, it is strongly urged and advised that professional guidance be obtained and a well-designed afforestation and silvicultural plan developed in advance of any work conducted. For an exceptional review and summarization of the afforestation literature, techniques, and practices within the Southern Mississippi River Alluvium, interested parties are directed to Gardiner et al. (2002).

Submodel

Description

This state is representative of the range of conservation actions that may be implemented and established on this ecological site. Apart from planting trees and managing for forest, one may elect to establish native herbaceous species and manage for predominantly a native grassland; a complex mixture of native grasses and forbs; or a pollinator planting whereby native forbs dominate the mix. In each of these options, it is strongly advised (possibly a programmatic requirement) that the species comprising the planting or seed mix consist of spring, summer, and fall flowering species. Depending on goals and objectives, various conservation programs and practices may be available. For additional information and assistance, please contact or visit the local NRCS Field Office.

Submodel