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Current Status of the Granite Pool Sprite, Gratiola amphiantha (Plantaginaceae), in Alabama
David M. Frings and Lawrence J. Davenport

Southeastern Naturalist, Volume 16, Issue 1 (2017): 59–69

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Southeastern Naturalist 59 D.M. Frings and L.J. Davenport 22001177 SOUTHEASTERN NATURALIST Vo1l6.( 116):,5 N9–o6. 91 Current Status of the Granite Pool Sprite, Gratiola amphiantha (Plantaginaceae), in Alabama David M. Frings1,* and Lawrence J. Davenport1 Abstract - Gratiola amphiantha (Granite Pool Sprite or Little Amphianthus) is a federally threatened plant species found in solution depressions formed on granite outcrops of Alabama, Georgia, and South Carolina. In Alabama, its distribution has recently been reduced from 3 to 2 counties along the eastern border in 8 small pools totaling less than 10 square meters. This study was initiated to monitor population numbers in Alabama, identify new populations, and make recommendations for the conservation of this species. Counts of individuals and pools were made in 2012 and 2013 at Penton (Chambers County) and Almond (Randolph County); a third site at Wehadkee Creek (Randolph County) was added in 2016. Numbers of individuals per pool differed dramatically; Pool P-3 dropped 72% from 2012 to 2013 before recovering partially (to -36%) in 2016. Densities were calculated for the larger pools, with Pool A-1 reaching 32.41 plants per 10 cm² in 2016. Because of habitat loss due to human disturbance—quarrying, recreational use, and dumping—G. amphiantha are close to extirpation in Alabama. A recovery plan, featuring the purchases of key properties, removal of competing vegetation, and the transferring of seed banks to additional pools, should be immediately implemented. Introduction Gratiola amphiantha D. Estes & R.L. Small (Granite Pool Sprite or Little Amphianthus) inhabits shallow vernal pools of granitic outcrops in the Piedmont province of the southeastern United States. Originally described as Amphianthus pusillus Torrey (1837) and maintained as a monotypic genus within the Scrophulariaceae, it has recently been subsumed as G. amphiantha and—due to the recent fragmentation of the scrophs—transferred to the Plantaginaceae (Estes and Small 2008). With its range restricted to Alabama, Georgia, and South Carolina (Fig. 1), the species is currently listed as threatened by the US Fish and Wildlife Service (Norquist 1988). Granite Pool Sprite is a winter annual that germinates from September through October in the very thin veneers of moist soil covering the bottoms of solution depressions etched into granitic expanses. The initial plant forms a small rosette of flat, opposite, linear, pointed leaves, each about 6 mm long. The pools collect rainwater during November and December, when the plants form several thread-like scapes growing to the pool’s surface (giving the species another colorful common name, Snorkelwort). The scapes are terminated by pairs of opposite, ovate, floating bracts, slightly longer and much flatter than the rosette leaves (Fig. 2). During late winter, Granite Pool Sprites form open (chasmogamous) white surface flowers, ¹Department of Biological and Environmental Sciences, Samford University, Birmingham, AL 35229. *Corresponding author - Manuscript Editor: Alvin Diamond Jr. Southeastern Naturalist D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 60 Figure 1. Range of Gratiola amphiantha (Granite Pool Sprite) in the southeastern United States. Figure 2. Floating leaves of Gratiola amphiantha (Granite Pool Sprite) at the Penton location. Southeastern Naturalist 61 D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 4 mm across, between the floating bracts. In addition, similar-appearing closed (cleistogamous) flowers develop from the subsurface rosette (Fig. 3). Self-pollination of both flower types results in bilobed capsules, each 2 mm across, filled with tiny seeds. The seeds remain dormant in the drying pools until the following season (Allison 1993, Hilton and Boyd 1996). The vast majority of Granite Pool Sprites reside in Georgia, especially on the granitic domes surrounding Atlanta. The species reaches its extreme western extent in neighboring eastern Alabama, where it once occurred in 5 locations across 3 counties of the Piedmont physiographic province: Blakes Ferry, Almond, and Figure 3. Cleistogamous flowers of Gratiola amphiantha at the Penton location in a drying pool near the end of a season. Southeastern Naturalist D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 62 Wehadkee Creek (Randolph County); near Penton (Chambers County); and off Thornton Road (Tallapoosa County) (Fig. 4; Keener et al. 2016). The population at Blakes Ferry (which is now a public park) has apparently been extirpated due to overuse for recreation; no plants were observed during a site visit over 20 years ago (Allison 1993) nor by the authors in 2010. The Thornton Road location, first observed in 2006 (A. Schotz, Auburn University, Auburn, AL, pers. comm.), has long been used as a rural dump site; no Pool Sprites were found there by the authors in 2013 and 2016. The disappearance of Granite Pool Sprite from the above 2 sites led directly to this study, which is part of a larger investigation of granite, sandstone, and limestone glades in central and northern Alabama. Previous work on Helianthus porteri (A. Gray) Pruski (Confederate Daisy) —which is known from similar glades and outcrops—appeared in this journal (Frings and Davenport 2015). Methods This study began in the winter of 2010 and continued until 2016. Sites with known Granite Pool Sprite populations were visited to verify population numbers during the months of December through February. In addition, potential Granite Pool Sprite sites were identified using a combination of Google Earth® and geologic maps of the Alabama Piedmont (Neathery and Reynolds 1975, Szabo et al. 1988). While the initial studies involved simply recording the presence or absence of Granite Pool Sprite, in 2012 we conducted a baseline survey to determine population numbers in the pools at Penton and Almond. To ensure accurate tallies, we placed an archeological-grade 1 m x 1 m grid over each pool to facilitate counting Figure 4. Current range of Gratiola amphiantha (Granite Pool Sprite) in Alabama. Southeastern Naturalist 63 D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 (Fig. 5). To ensure consistency, only 1 of us (D.M. Frings) performed the actual count. Because Granite Pool Sprite rosettes may send up more than one scape, only the rosettes were tallied. Counts were repeated at Penton and Almond in 2013 and 2016. In 2016, we added an additional site (Wehadkee Creek) to the study. We deposited voucher specimens for all sites in the Samford University Herbarium (SAMF), Birmingham, AL. Results In total, we examined 7 Alabama sites for the presence of Gratiola amphiantha; their key characteristics are recorded in Table 1. Of these sites, 5 were previously known to support this taxon: Almond, Blakes Ferry, Penton, Wehadkee Creek, and Thornton Road. We also searched for the species at 2 additional granitic glades, New Harmony and Roxana, but did not find it at either location. The Alabama populations of Granite Pool Sprite occur on several rock types: from fine- to medium-grained trondhjemite, coarse- to medium-grained gneiss, and quartz-diorite gneiss (for details, see Neathery and Reynolds 1975). These domeshaped outcrops or monadnocks, of Precambrian to Paleozoic age, weather slowly, forming shallow depressions or pools on the surface. Over time, most of these depressions trap enough soil (and moisture) to support the successional growth of mosses, herbaceous vascular plants, and (finally) woody vascular plants. A limited number of depressions accumulate very little soil, retaining pools of rainwater from autumn until early spring—perfect ephemeral habitat for Granite Pool Sprite. Figure 5. Lead author performing annual count of Gratiola amphiantha (Granite Pool Sprite) using an archeological grid at the Almond location. Southeastern Naturalist D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 64 Table 1. Field data and presence of Gratiola amphiantha (Granite Pool Sprite) in Alabama: AT = Almond trondhjemite, RMGG = Rock Mills granite gneiss, DCHG = Dadeville Complex Camp Hill gneiss. Location Province County Elevation in m (ft) Formation Rock type Soil pH Voucher Blakes Ferry Piedmont Randolph 242–255 (794–835) AT Trondjhemite - Not present Almond Piedmont Randolph 230–255 (755–835) AT Trondjhemite 6.1–6.3 Davenport 4158 Wehadkee Creek Piedmont Randolph 234–240 (769–788) RMGG Granite gneiss Davenport 6011 Penton Piedmont Chambers 230–255 (755–835) RMGG Granite gneiss 4.4–6.9 Davenport 4157 Thornton Road Piedmont Tallapoosa 223–228 (730–749) DCHG Granite gneiss Not present New Harmony Piedmont Tallapoosa 192–228 (629–748) DCHG Granite gneiss 6.4–6.9 Not present Roxana Piedmont Lee 208–230 (682–755) DCHG Granite gneiss - Not present Southeastern Naturalist 65 D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 The Penton location consists of 3 pools on the Rock Mills granite gneiss (which is included in the Dadeville Complex), a coarse- to medium-grained biotite granite gneiss (Neathery and Reynolds 1975). The largest pool (P-3) is slightly greater than 1 m2; pools P-1 and P-2 are approximately 0.25 and 0.5 m2, respectively. The total baseline population of Gratiola amphiantha at Penton dropped from 2017 individuals in 2012 to 559 in 2013—a 72% decrease (Table 2). The total 2016 population was 1290, a 36% drop from 2012. It should be noted, also, that Pool P-1—which showed ~10 individuals upon visual inspection in 2010—had no plants in 2012 and 2013. However, 15 plants were observed in 2016. Such appearance/disappearance cycles will be discussed in the next section. The Granite Pool Sprite population at Almond consists of 3 pools on the Almond trondhjemite, a fine- to medium-grained, foliated trondhjemite with abundant muscovite or biotite and epidote (Neathery and Reynolds 1975). All 3 pools are ~1 m in diameter. From the baseline total count of 1655, this population dropped to 1270 (-23%) in 2013; the 2016 population of 1588 was 4% below the baseline. In 2016—thanks to a landowner’s permission—a second Randolph County population, near Wehadkee Creek, was added to the study. Like the Penton population (Chambers County), the glades at this location are formed on Rock Mills granite gneiss. This population consists of 2 pools: W-1 (~0.25 m²) with 2 plants, and W-2 (~2 m²) with 724 plants. As part of this study, we calculated the densities of Granite Pool Sprite in all 3 pools located at Almond, and the largest pool, P-3, at Penton (Table 2). These pools are similar in size, ~1 m2 each. Plant densities were calculated by adding the Table 2. Annual population counts and densities per 10 cm2, in the years 2012, 2013, and 2016, for Gratiola amphiantha (Granite Pool Sprite) at each of the Alabama locations that contain current or historic occurrences. 2012 2013 2016 Location County Count Density Count Density Count Density Penton, Al P-1 Chambers 0 - 0 - 15 - Penton, Al P-2 Chambers 170 8.50 184 7.36 251 - Penton, Al P-3 Chambers 1847 26.16 375 6.20 1024 10.76 Total Penton populations 2017 - 559 - 1290 - Almond, Al A-1 Randolph 489 13.22 407 13.13 619 32.41 Almond, Al A-2 Randolph 185 4.20 265 5.64 507 6.97 Almond, Al A-3 Randolph 981 10.94 598 8.19 462 6.73 Total Almond population 1655 - 1270 - 1588 - Blakes Ferry, Al Randolph 0 - 0 - 0 - Wehadkee Creek, Al W-1 Randolph 0 - 0 - 2 - Wehadkee Creek, Al W-2 Randolph 0 - 0 - 724 - Total Wehadkee population - - - - 726 - Thornton Road, Al Tallapoosa 0 - 0 - 0 - Roxanna, Al Lee 0 - 0 - 0 - Total annual population 3672 - 1829 - 3604 - Southeastern Naturalist D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 66 number of plants in each 10-cm2 block, then dividing by the number of occupied blocks. The plant density of 26.16 recorded in pool P-3 at Penton was the highest for the 2012 baseline study; its density dropped to 10.76 in 2016. Pool A-1 at Almond had the highest plant density recorded, 32.41, during the 2016 survey. As noted previously, we also checked for new and historical populations. The Roxana site (Lee County), although known to support Confederate Daisies (Frings and Davenport 2015), which require similar kinds of rock expanses, has no Granite Pool Sprites. Thornton Road (Tallapoosa County), which supported one pool of ~150 individuals in 2006 (A. Schotz, pers. comm.), has none today. The Blakes Ferry population (Randolph County), documented and described in the 1930s by botanist Roland Harper of the Geological Survey of Alabama (Harper 1939), has been extirpated due to vehicular traffic and recreational abuse. An additional pool west of the current Almond population, on a huge monadnock owned by a local church, was collected and vouchered as recently as 1984 (Keener et al. 2016). No Granite Pool Sprites have been observed there since (A. Schotz, pers. comm.). Conclusions Our studies show that, in the state of Alabama, Granite Pool Sprite is currently restricted to 3 populations inhabiting 8 ephemeral pools, totaling less than 10 m2, located in 2 counties of the Piedmont. One of the 2 most-studied populations, at Penton, showed wild fluctuations in numbers, dropping 72% between 2012 and 2013, with one small pool “losing” its plants temporarily. The second main population, at Almond, also dropped significantly before “settling” at 4% below its 2012 baseline number. Although alarming, such fluctuations can be expected. Appearance, disappearance, and total population numbers are based on moisture regimes during late autumn and winter. Pool populations are maintained by seed banks in their gravelly bottoms; such banks “may be 18 times greater [in number] than the germinating plants in a given year” (Rickard 2005:9). Some populations may also be affected by freezing weather, with individual plants uprooted by shifting ice (B. Keener, University of West Alabama, Livingston, AL, pers. comm.). When present, plant densities may be extremely high. In our studies, the density at A-1 reached 32.41 plants per 10 cm² in 2016. Such densities compare well to those found in the robust Georgia populations studied by Hilton and Boyd (1996). In fact, transplant studies by those 2 authors found an “ideal” density (with no intraspecific competition) of 14 plants per 10 cm²—well within the range found at some Alabama pools. Based on Granite Pool Sprite population numbers and plant densities, some of Alabama’s pools appear to be quite healthy and sustainable. However, every population suffers a precarious existence. All Alabama populations are located on private property, which decreases the protection afforded by the US Endangered Species Act of 1973. In addition, each Alabama population faces additional nearby threats. The 3 Penton pools are perched within 100 m of an abandoned quarry where Southeastern Naturalist 67 D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 broken glass, household trash, and ATV tracks are prevalent. The Almond pools occupy a flat expanse near a county road, and piles of household and construction debris are found within 30 m of the site. Even though the Wehadkee Creek site is protected by a vigilant landowner, both pools there are located within 20 m of the rim of an abandoned quarry. These pools also lack intact rock rims, which are needed to restrict drainage (Rickard 2005). Two other Alabama Granite Pool Sprite populations have been extirpated in recent years—Blakes Ferry probably due to recreational overuse, and Thornton Road likely due to dumping (Fig. 6). Each of the above stresses is listed and described in the recovery plan (Allison 1993) published for this federally listed threatened species. In addition, Gratiola amphiantha is “stressed” by being a pioneer successional species. As such, it requires shallow pools with little organic matter. If organic matter increases, then enough soil develops to support its main competitor, Diamorpha smallii Britton (Elf-Orpine or Small’s Stonecrop; Allison 1993, Hilton and Boyd 1996). As the soils deepen and retain more moisture, the depressions become vegetated “islands” supporting a successional array of larger, dominant, shade-tolerant, and shade-producing species; the final climax community includes trees and shrubs (Burbanck and Phillips 1983, Burbanck and Platt 1964, McVaugh 1943, Oosting and Anderson 1939, Quarterman et al. 1993, Shure and Ragsdale 1977). Such a trend is currently seen at the Almond site, where Pools A-1 and A-2 support small numbers of Elf-Orpine and several species of grasses that are forming thicker soils Figure 6. The Thornton Road location has become a rural dump site which may have led to the extirpation of Gratiola amphiantha (Granite Pool Sprite). Southeastern Naturalist D.M. Frings and L.J. Davenport 2017 Vol. 16, No. 1 68 and small mats. If this successional process continues, the Granite Pool Sprite pools will eventually dry up. The recent decline in the Alabama populations of Granite Pool Sprite shows potential for extirpation within the species’ westernmost range. To prevent such a fate, we recommend that the status of Granite Pool Sprite be reassessed—reclassified in Alabama from threatened to endangered—and that a recovery plan be developed specific to the state. We suggest that such a plan include: (1) securing and protecting the glades at Penton and Almond that support its largest populations; (2) removal of competing vegetation at Almond; (3) establishing additional populations at all sites by the transfer of seed banks to nearby pools; and (4) conducting yearly site surveys, as recommended for Alabama in the federal recovery plan (Allison 1993). In addition, the second historical Almond site should be purchased as a publicly protected area and “new” populations returned to it. Acknowledgments We thank Jimmy Rickson (USFWS), Steve Ginzbarg (University of Alabama), Brian Keener (University of West Alabama), Steve Krotzer (Alabama Power Company), and Al Schotz (Auburn University). All of these colleagues readily shared important information on Alabama populations of Gratiola amphiantha. We also thank our 2 reviewers for their very helpful comments and suggestions. Literature Cited Allison, J.R. 1993. 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