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Louisiana

Upper West Gulf Coastal Plain

Today, the natural forests have been almost completely replaced by agricultural crops.


The Upper West Gulf Coastal Plain ecoregion is the third largest ecoregion in Louisiana and covers approximately 7,100 square miles. This region is bounded by Texas on the west, Arkansas on the north, Bayou Bartholomew/Ouachita River on the east, and the longleaf pine region on the south. This ecoregion is a portion of the larger Upper West Gulf Coastal Plain, which includes southwest Arkansas, southeast Oklahoma, and northeast Texas. Given the large size of this ecoregion, it is not unexpected to find that the diversity of habitats and species is among the greatest in Louisiana.

Historic Condition

In 1871 and 1872, Colonel Samuel H. Lockett traversed the state of Louisiana to conduct a topographic survey and to report on people, botany, geology and natural history he encountered. Lockett termed northwest Louisiana as the "good uplands" in regards to the potential for agriculture and timber production, and described the region as "generally hilly, some of the ridges being almost mountainous in elevation." "From the tops of the lofty, red-land hills there are some wide and pleasing [vistas]."Although "mountainous" may not be an adjective we would ascribe to Louisiana today given our broader range of experience, northwest Louisiana is decidedly hilly and does contain the highest point in Louisiana, Driskill Mountain, in Bienville Parish, which towers 535 feet above sea level. Of special significance, Louisiana can be proud of having the third lowest highest point in the U.S., beaten out by only Delaware at 442 feet and Florida at 345 feet.

Locket described the upland forests of this region as being "very good", dominated by shortleaf pine and a variety of oaks, hickories, and other hardwoods. E. W. Hilgard also examined the agricultural potential of Louisiana in the latter half of the 19th century and classified the plant communities of northwestern Louisiana into four general categories: hill red lands supporting shortleaf pine and oak-hickory forests, brown loam lands comprised of broad to rolling upland ridges supporting more mesic hardwood forests of oak and hickory, level areas of pale sandy loam lands supporting post and blackjack oaks with shortleaf pine, and level, poorly drained gray soils supporting loblolly pine flatwoods.

Lockett reported that the alluvial valleys of the Red River and other major rivers supported bottomland hardwood forests and "the best cotton lands in the world." Lockett described in some detail the "Great Raft" of trees that blocked all navigation and caused extensive backwater flooding. At times, the raft grew to nearly 100 miles in length and extended "solidly from bank to bank, a matted mass of tree tops and trunks, weeds and canes, with cottonwood and willow trees growing upon its surface." The Red River has had a long history of diligent activities by man to allow unimpeded travel from the Mississippi to Shreveport, culminating in the major navigation improvements completed this decade.

Current Condition

Today, although the topography(topography-practice of graphic delineation in detail usually on maps or charts of natural or man-made features of a place or region) in this region has not changed, the natural forests have been almost completely replaced by agricultural crops in the lowlands and intensively managed pine forests in the uplands. The Louisiana Natural Heritage program estimates that less than 10% of original shortleaf pine-hardwood forests remain today. Preliminary surveys for natural forests in the upland portions of this region indicate that few areas remain in a relatively natural condition; Acreage loss of short leaf pine are of more concern than mature stands because of structural and compositional changes that have occurred in the short leaf pine system. It is probable that even the best examples of this system present today in Louisiana do not closely approximate historic conditions.

As with longleaf pine-dominated plant communities, shortleaf pine habitats were greatly influenced by periodic fire, which is estimated to have occurred at a frequency of about once every 5 to 15 years in the uplands of this region. Due to fragmentation of landscape, changes in land use and active fire suppression, many sites that were formerly open woodlands with a rich understory and ground layer have undergone significant changes in plant species composition and have often become closed-canopy forests lacking many of the plant species that require a high degree of exposure to sunlight.

The pattern of habitat loss noted in the uplands has been repeated in the lowlands with virtually all of the original bottomland hardwood forests having been converted to agriculture. An exhaustive inventory of wetlands in Caddo and Bossier Parishes by TNC, identified several high-quality wetland sites worthy of TNC conservation efforts , but also reinforced the belief that relatively natural forested habitats were extremely uncommon and those that remained were often small, fragmented and highly isolated.

Biodiversity Significance

Although the shortleaf pine uplands and the bottomland hardwoods found in the alluvial valleys of the major rivers are the two predominant natural plant communities found in this region, they are but two of 18 recognized by the Natural Heritage Program. Four distinct prairie types are known in this region, including morse clay calcareous prairie, which is considered globally endangered. Unusual upland forests include calcareous forest and western xeric sandhill woodland, the latter considered globally threatened. Of the 18 natural plant communities found in this region, 13 have at least one example afforded a reasonable amount of protection.

Although protection of natural plant communities generally ensures that common species of plants and animals are also protected, conservation of rare species requires special consideration of their special needs and distribution. 30 species of plants found in this region are considered globally rare, threatened or endangered; ten are found nowhere else in Louisiana. Some of the rare plants include slender blazing star, Texas trillium, Louisiana bluestar, yellow ladies slipper orchid, Arkansas oak, and scarlet catchfly.

Twenty-four species of animals found in this region are considered globally rare, threatened or endangered; six are found nowhere else in Louisiana. Some of the rare animals include the pink mucket mussel, several Schoolhouse Springs insects, bluehead shiner, western sand darter, interior least tern, red-cockaded woodpecker, and Bachman's sparrow. Of the 24 rare animal species found in this region, eight have received some degree of protection thus far.

Conservation Efforts

Caddo Black Bayou has been a focal point for the Conservancy in recent years. TNC currently owns nearly 500 acres in this area, which was identified as supporting one of the best xenic sandhill communities in Caddo/Bossier parishes and excellent wetland habitats. Schoolhouse Springs Preserve, which supports numerous rare aquatic species, was one of TNC's earliest acquisitions in Louisiana, and we acquired additions to Bodcau Bayou and Loggy Bayou Wildlife Management Areas. In addition, we have worked extensively on the Minden Ammunition Plant, Barksdale Air Force Base and Bodcau Wildlife Management Area to conduct natural resources inventories and to develop recommendations for management and natural area designation. Our work with the Corps of Engineers at Bodcau WMA resulted in eight areas and nearly 4,000 acres being designated as natural areas through the natural areas registry program jointly sponsored by TNC and LNHP.

Opportunities for Public Visitation

Areas open to public visitation include D'arbonne National Wildlife Refuge, Upper Ouachita National Wildlife Refuge, Bodcau Wildlife Management Area, Loggy Bayou Wildlife Management Area and the Caney District of Kisatchie National Forest. Although developed trail systems and facilities for visitors are generally limited, most of the public lands have constructed some amenities for nature enthusiasts. Bodcau Wildlife Management Area in Bossier Parish provides an excellent introduction to this region. Bodcau WMA supports many high-quality examples of natural plant communities and the Corps of Engineers maintains a very nice camping area. The two TNC preserves, Schoolhouse Springs and Caddo Black Bayou, are only accessible by crossing private property, so visitation is limited to scheduled TNC field trips.

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