Common (Translated Scientific) Name: Big Bluestem - Switchgrass - Little Bluestem - Slender Little Bluestem - Ashy Sunflower Grassland

Colloquial Name: Eastern Upland Coastal Prairie

Hierarchy Level:  Association

Type Concept: This is the upland, mesic (non-wet) coastal prairie that, along with wet coastal prairie, historically dominated vast acreages on the Pleistocene Prairie Terraces of southwestern Louisiana. It occupied the broad, slightly convex ''flats'' across the region. In areas of pimple mounds, this type occupied the mounds, with wet coastal prairie (~Panicum virgatum - Tripsacum dactyloides - (Panicum hemitomon) Grassland (CEGL007937)$$) in low areas between mounds. The prairie landscape was bisected by "gallery forests" along small permanent streams that divided the prairie into "coves." Upland prairie is typically dominated by the nominal species, but a large variety of other species is associated with the type. Composites, grasses, sedges and legumes are the primary families represented, but many other families are present. Over 500 plant species have been recorded in Louisiana''s remnant coastal prairies. The vegetation in the northern coastal prairies greatly resembles that of the mesic longleaf pine flatwoods (the two intergrade at the northern boundary of the coastal prairie in Louisiana), with very few species apparently restricted to the prairies. Soils in these areas are generally acidic, fairly nutrient-poor silt loams. Toward the south, the vegetation is influenced by heavier clay soils, with some of the clays being sub-calcareous to calcareous, and in these areas there are some strict calciphiles present (e.g., Dalea candida) and fewer species characteristic of the acidic silt loams to the north. Historically, upland coastal prairie was maintained by frequent burning and soil conditions generally inhospitable to the growth of trees and shrubs.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: The coastal prairies of southwestern Louisiana are estimated to have occupied over 2 million acres as recently as 1900. Essentially all of this land was placed into agriculture in the early 1900s. In Louisiana at present, there are less than 500 acres of this community type known to remain in relatively natural condition, and essentially all examples known to remain are found along railroad tracks. The type as here described incorporates the former Panicum virgatum - Tripsacum dactyloides - Schizachyrium scoparium Herbaceous Vegetation (CEGL004034) [Louisiana "central coastal prairie"], and the former Schizachyrium scoparium - Schizachyrium tenerum - Andropogon gerardii Herbaceous Vegetation (CEGL004076) [Louisiana "northern coastal prairie"]. Both of these types had been devised by L. Smith after discussions with Charles Allen in about 1997 and were based on Allen''s field observations and eye-ball assessment of his plot data. The development of these two types also was influenced by a belief that there probably are differences in the coastal prairies of Louisiana from north to south; this line of thinking is probably in part due to a delineation by Hilgard in 1880 of a "gray silt" coastal prairie to the north (adjoining the longleaf pine flats), and a "black calcareous" type in a belt along the southern tier of the coastal prairies. While soil differences do exist across the upland prairie, data are insufficient at this time to distinguish different upland prairie types that may have been associated with different soil types. Hilgard also recognized a "brown loam" type occupying a large area on loess-derived soils in the eastern body of the Louisiana coastal prairies; this latter type has not to this point been classified as a distinct type by Louisiana Natural Heritage or NatureServe in the U.S. National Vegetation Classification, and none of the type is known to remain.

The type as described here also combines the two "upland" types described by Jim Grace after his analysis of Charles Allen''s data in March 1999. Grace defined the first of these types, "Panicum virgatum - Andropogon gerardii Herbaceous Vegetation," as a "later successional" upland prairie (less disturbed), and the second type, "Euphorbia corollata - Tephrosia onobrychoides - Schizachyrium scoparium Herbaceous Vegetation," he classed as an "earlier successional" upland prairie (more disturbed, including fire as a disturbance) [note: L. Smith does not recognize these species as any more indicative of disturbance than the nominal species for Grace''s "later successional" type; in fact, I would rate these species as indicative of a high-quality site and need to review further with Grace]. These were the only two upland prairie "types" he could determine from his analysis of Allen''s data, which he indicated were difficult to analyze for various reasons.

Allen and Vidrine (1997) recognized only one prairie type in the ten coastal prairie remnants they studied, and termed this prairie "Panicum virgatum - Schizachyrium scoparium - Schizachyrium tenerum - Helianthus mollis - Andropogon gerardii prairie," based on the 5 species with the highest importance value scores in plot sampling in 1987. This is essentially the name that is applied herein for upland coastal prairie. Because none (very few?) of the sample plots in this study were in wet places (M. Vidrine pers. comm.: "the wet spots were all grown up in bushes"), their one recognized type is here considered to be synonymous with the upland type described above. The relationships of this type to other coastal prairies in the classification need to be determined. In particular, this community may be the same or overlap in large part with the concept of ~Schizachyrium scoparium - Paspalum plicatulum - Sorghastrum nutans - Dichanthelium oligosanthes - Symphyotrichum pratense Alfisol Grassland (CEGL002208)$$. Since Schizachyrium scoparium is a dominant species, this association is placed in a Schizachyrium scoparium alliance, to better correspond to other coastal prairie associations. According to Diamond and Smeins (1988) Schizachyrium scoparium replaces Andropogon gerardii in importance in the coastal prairie of Texas; this may apply to Louisiana as well.

Similar NVC Types: No Data Available

note: No Data Available