What makes this preserve unique?
Copenhagen Prairie /Ouachita Hills is one of the most ecologically important areas in Louisiana, and is without question one of the most significant botanical sites in the state. Owing mainly to an extensive outcropping of calcareous (containing high levels of calcium carbonate; “limey”) and acidic clays associated with the Jackson Formation, and to some as of yet undetermined events in the complicated history of plant geography, this area supports a rich assortment of restricted ecological communities and plant species. Many of these elements are rare to very rare, and many are found only here in Louisiana. Several unique and globally-rare plant community types characterize the area, including calcareous prairies, upland and bottomland calcareous forests and cedar woodlands. These various habitats occur in a complex mosaic created by a series of steep slopes, deep ravines and broad ridgetops. Many of the slopes descend directly to the Ouachita River. The calcareous nature of the soils, in combination with very high clay content, strongly controls plant species composition and community structure.
No fewer than 26 plant species found at the site are considered state or globally rare, 12 of which have been recorded nowhere else in the state. Because of the nature of the site, it is highly likely that other rare species are present that are yet undiscovered. The site is exceptionally rich in native woody plants. Inventories by the Louisiana Natural Heritage Program of the Louisiana Department of Wildlife and Fisheries indicate that Copenhagen may support more native woody plant species per square mile than any other area in Louisiana, and may rival or exceed any area in the continental U.S., outside of tropical Florida, at that scale.
Small prairie openings are found along the upper slopes and ridgetops in the northern part of the project area. The prairies are dominated by warm-season tall grasses, and support a wide variety of grasses and forbs such as little bluestem (Shizachyrium scoparium), praire dropseed (Sporobolus asper), Indian grass (Sorghastrum nutans), Indian plantain (Arnoglossum plantaginifolia), prairie petunia (Ruellia humilis) and compass-plant (Silphium laciniatum). State-rare species include prairie pleat-leaf (Nemastylis geminiflora), side-oats gramma (Bouteloua curtipendula), purple prairie bluets (Houstonia purpurea var. calycosa) and purple coneflower (Echinacea purpurea). This is apparently a partially fire-maintained community that is experiencing some encroachment of woody species from adjacent woodlands due to recent exclusion of fire.
Upland calcareous forests and woodlands are found on slopes and ridgetops and are dominated by a wide variety of hardwoods, but loblolly pine (Pinus taeda) and shortleaf pine (P. echinata) are common. Some of the characteristic calciphilic hardwoods are white ash (Fraxinus americana), honey locust (Gleditsia triancanthos), nutmeg hickory (Carya myristiciformis), cedar elm (Ulmus crassifolia), chinkapin oak (Quercus muhlenbergii), shumard oak (Q. shumardii), and southern sugar maple (Acer barbatum). Some rare plant species found in these forests include wahoo (Euonomys atropurpureus), crested coral-root (Hexalectris spicata), Oglethorpe oak (Q. oglethorpensis), durand oak (Q. sinuata var. sinuata), three-flowered hawthorn (Crataegus triflora), and white-leaved leather flower (Clematis glaucophylla).
Of note is the diverse marine fossil component of the soils. Oyster and clam shells, coral, and shark teeth are commonly encountered, and fossilized bones of ancient whales have been recovered in the area.
Upland acid clay forests, characterized by upland hardwoods, such as southern red oak (Quercus falcata), post oak (Q. stellata), blackjack oak (Q. marilandica), white oak (Q. alba), mockernut hickory (Carya tomentosa), mixed in roughly equal proportion with shortleaf and loblolly pines, occupied the majority of the rugged hills of the area in which this preserve is located. While relatively few rare species are known from this forest type, these forests are important centers of native biodiversity. While a few examples of mature natural forest remain, the vast majority of these forests have been converted into short-rotation, loblolly pine plantations.
Why TNC Selected This Site
The Nature Conservancy selected this site because of it is truly one of the botanical treasures of Louisiana. This preserve supports a number of globally-rare natural plant communities, which in turn support a wide variety of rare plants, including at least 12 that are known in Louisiana only from this area.
What TNC Has Done/Is Doing
The conservation vision for this property is to restore the historic structure, composition, functional processes, and geographic extent of all associated natural communities, with an emphasis on rare calcareous prairies and woodlands. TNC is working to restore the prairies and historically open surrounding woodlands by reducing the off-site tree component, applying prescribed fires, and removal of off-site trees and shrubs within prairies.