|Scientific Name:||Quercus arkansana Sarg.|
|Taxonomic Source(s):||Trehane, P. 2007-2015. The Oak Names Checklist. Available at: http://oaknames.org/search/goodnames.asp. (Accessed: 2 February 2016).|
|Red List Category & Criteria:||Vulnerable B2ab(ii,iii,v) ver 3.1|
|Assessor(s):||Jerome, D., Wenzell, K. & Kenny, L.|
Restricted to the Coastal Plain of the southeastern United States, Arkansas Oak (Quercus arkansana) is a likely relict species that occurs sporadically in isolated stands. Despite its wide range from Georgia to eastern Texas—with an estimated extent of occurrence (EOO) of roughly 345,000 km2—its small, fragmented occurrences give it a restricted area of occupancy (AOO) of about 1,000 km2. This species is severely fragmented, with most subpopulations too isolated to allow for seed dispersal between occurrences. Threats from commercial logging, conversion of habitat to pine plantations, and unfavourable land management continue to drive declines in habitat quality and population size. Additionally Q. arkansana is projected to lose over 60% of its suitable habitat due to climate change according to recent climate change modelling (Hargrove et al. 2016, Potter et al. 2017). This passes the threshold needed to assess Q. arkansana as Endangered under A3c. However, in this case it is uncertain whether there is a linear relationship between habitat decline and population decline, as the population density and adaptive capacity of this species is unknown. Due to these uncertainties, and other assumptions inherent in climate change modelling, these habitat suitability predictions were not used to strictly apply the categories and criteria of the Red List and Quercus arkansana is considered Vulnerable.
|Previously published Red List assessments:|
Arkansas Oak is endemic to the southeastern United States, mainly along the Gulf Coastal Plain where it occurs sporadically in scattered sites. This species can be found from the states of Georgia into eastern Texas, but its range is divided by the Mississippi River Delta, from which it is believed absent. Given this wide span, this species' estimated EOO is roughly 345,000 km2; however, because of its small, scattered occurrences, the area of occupancy AOO of Arkansas Oak is restricted, estimated to be about 1,000 km2 (based on extensive research of known occurrences, using over 360 coordinate data points). One occurrence has been reported from eastern Georgia, which represents the far eastern edge of the range and the only known report of this species from the Atlantic Coastal Plain. Arkansas Oak is believed to be a relictual species, with a historically wider range that is now restricted to isolated subpopulations, most often localized around mesic sandhills, ravine slopes and stream heads.
Native:United States (Alabama, Arkansas, Florida, Georgia, Louisiana, Texas)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Considered a relict species, Quercus arkansana is found in isolated, scattered occurrences across the southeastern US. Previously considered endemic to the Coastal Plain of the Gulf of Mexico, a 1989 report of the species from eastern Georgia represented an eastern range extension for the species and its first documented occurrence from the Atlantic Coastal Plain. An inconspicuous understory tree, Arkansas Oak can easily be overlooked and is likely under collected, though it is known to be infrequent and quite uncommon throughout most of its range, with most stands isolated and containing just a few to a few dozen individuals. The exceptions to this are a number of areas of local abundance, namely in southwestern Arkansas and the Florida panhandle, where healthy subpopulations support thousands of trees. In southwestern Arkansas, where the species was first collected and for which it was named, the species is considered fairly stable and abundant in several localized sites (B. Baker pers. comm. 2015). Within a narrow range in the Florida panhandle, large subpopulations hold thousands of plants and are reported to be healthy and thriving in this restricted area (G. Knight pers. comm. 2015).|
Throughout the majority of its range, Q. arkansana occurs in small, severely fragmented subpopulations, with many occurrences holding only a few (one to five) to a few dozen individuals. These occurrences are often separated by several to many kilometres, distances greater than the typical maximum value of about 600 m reported for dispersal of acorns by animals, and much greater than the typical dispersal distance of about 100 m or less (Pons and Pausas 2007). This means that stands that are wiped out are unlikely to be recolonized from remaining occurrences, given the distance of unfavourable habitat separating them. While a few large subpopulations of Arkansas oak exist in southwestern Arkansas and Florida (recorded by state agencies as Element Occurrences separated by at least one kilometre), these represent only a portion (less than half) of the total AOO of Q. arkansana, the majority of which represents small, patchily distributed occurrences across the southeastern US.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Arkansas Oak, a small- to medium-sized shade-loving tree, can reach heights of 15 m but is often much smaller, about one to eight metres in height. This species favours fine loamy sand and other well-draining sandy soils. Quercus arkansana grows in the understories of mesic pine forests and southern hardwood stands, and it is often reported from sandhills, along the upper portions of ravines, steepheads and above the heads of small streams. In southwestern Arkansas, Q. arkansana was once thought to be restricted to sandhill habitat but has since been found to occur more commonly outside this habitat than previously thought (B. Baker pers. comm. 2015). Nonetheless, Arkansas Oak is typically infrequent where it occurs, making up as little as five to 10% of woody vegetation at sites in the eastern part its range (A. Diamond pers. comm. 2015). This species is rarely a dominant component of the vegetation, except for the few localities in Arkansas and Florida where it is locally abundant in sizeable stands (T. Patrick pers. comm. 2015).|
Arkansas Oak grows alongside Pinus taeda, P. echinata and other pines, oaks such as Q. nigra, Q. pagoda, Q. margarettae and Q. hemisphaerica, and various hardwoods including Carya spp., Nyssa sylvatica, Liquidambar styraciflua, Vaccinium arboreum, Sassafras albidum, Magnolia grandiflora and Diospyros virginiana. Hunt (1986) noted putative hybrids between Q. arkansana and Q. nigra in Georgia, and introgression from Q. falcata has been observed in Texas. Such hybridization is unsurprising given the high ratio of habitat edge to subpopulation area of Arkansas Oak's small, isolated occurrences, particularly at the edges of the species' range (Hunt 1986).
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Use and Trade:||Quercus arkansana is not widely considered a valuable timber species, but it is one of the red oaks and have been used for caskets, crossties, flooring, fuelwood and furniture. This tree is cultivated and sold as an ornamental by a small number of native plant nurseries in the region.|
Quercus arkansana faces threats from the conversion of its habitat to pine plantations. Commercial forestry practices such as timber harvest and prescribed burns threaten small, scattered occurrences of this species: detrimental impacts of silviculture on several subpopulations have been documented, and stands at some sites have been reported to have been destroyed (Hunt 1986, Georgia DNR 2015, ANHC 2015, ALNHP 2015). Another threat is the clearing and unfavourable management of land. One large subpopulation in southwestern Alabama, which occurs on land recently designated as the Pike County Pocosin Nature Preserve, has since experienced losses of these trees on uplands due to management practices aimed at promoting Gopher Tortoise and game species by encouraging pines and removing oaks through the use of fire and herbicide (A. Diamond pers. comm. 2015). In many cases, it is this species' habit of occupying ravine slopes and stream heads that best protects it from destruction or removal. Recent reports of occurrences in Alabama have also noted dieback of trees, causing the majority of individuals to grow as stump sprouts just a few meters tall. While the precise cause of this dieback is not known, recent years of drought have been suggested as a possible cause (A. Diamond pers. comm. 2015). Private land ownership of many sites and introgression from more common red oaks (particularly in light of this species' ecology and sporadic distribution) pose additional threats to Arkansas Oak.
Additionally a major threat to Quercus arkansana is habitat shifting under climate change, as evidenced by a recent study that projected declines in suitable habitat area by of over 60.48% under projections for 2050 (Hargrove et al. 2016). A recent study by Potter et al. (2017) used species specific traits to asses trees in three vulnerability categories: 1) exposure to climate change, which included projected area change by 2050 and distance to future habitat; 2) sensitivity to threat, which included rarity, area of distribution, dispersal ability, and disturbance tolerance; and 3) adaptability to threat, which included regeneration, genetic variability, and ecological requirements. Quercus arkansana was in the group with high values for all three vulnerability categories. It was found to have high exposure to the threat of climate change, high sensitivity to this threat and low adaptability (Potter et al. 2017).
|Conservation Actions:||Arkansas Oak is considered globally Vulnerable (G3) by NatureServe and is listed as an S2/State Imperiled species in Georgia, Alabama and Louisiana and S3/State Vulnerable in Florida and Arkansas (though the state of Arkansas discontinued regular tracking of Quercus arkansana in 2010 due to local abundance and fairly stable subpopulations; B. Baker pers. comm. 2015). While little recent attention has been given to the conservation of Arkansas Oak, subpopulations are known to occur on numerous protected areas throughout the range, including Caddo Black Bayou Preserve (TNC) in Louisiana, several natural areas in Arkansas, Hannahatchee Wildlife Management Area in Georgia, the Oakmulgee Division of the Talladega National Forest in Alabama (where it is listed as a sensitive species), and importantly Eglin Air Force Base in Florida, which holds thousands of trees in healthy subpopulations and which protects the plants through an effective land management program (G. Knight pers. comm. 2015, L. Anderson pers. comm. 2015, T. Patrick pers. comm. 2015). According to BGCI, Q. arkansana is currently held in 28 ex situ collections worldwide, but additional effort should be invested in collecting and cultivating seed from genetically diverse sources, protecting habitat and regularly monitoring subpopulations.|
|Citation:||Jerome, D., Wenzell, K. & Kenny, L. 2017. Quercus arkansana. The IUCN Red List of Threatened Species 2017: e.T30953A88108282.Downloaded on 28 May 2018.|
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