Melissa Caspary, Ph.D. candidate at the University of Georgia School of ecology, is researching the impacts of exotics species on granite outcrop species, including Amphianthus pusillus. Hilton and Boyd (1996) examined microhabitat requirements, density-fecundity relationships, and microdistribution of Amphianthus pusillus on a granite outcrop in Heard County, Georgia. They found that abiotic features of Amphianthus pusillus habitat varied widely, with water depth varying 93-fold and soil depth 22-fold. There was no relationship between soil depth and Amphianthus fecundity. Density and fecundity of the co-occurring species, Diamorpha smallii, also failed to correlate with Amphianthus pusillus density and fecundity. They concluded that variables considered important in defining Amphianthus habitat at a coarse scale (water, soil depth, etc.) are not as important at the finer scale at which their study was conducted. They speculate that variables such as microsite history, seed predation, and seed bank size are more important at fine scales, and that unoccupied suitable habitat exists within pools. Implications for conservation management: since suitable habitat is difficult to define and may depend on easily disturbed microsite factors, habitat manipulation is not recommended; however, sowing seeds of Amphianthus into pools known to currently or historically support the species may be successful in restoring and producing robust populations.

Pool sprite populations are dependent on seasonal inundation and are destroyed by siltation and sedimentation into pools. Therefore, site management must include protection from erosion which deposits silt and debris into pools, and water diversion which leads to permanent drying. Other management recommendations include: Protect granite outcrops from quarrying, trash dumping, and off-road-vehicle use. Direct foot traffic away from rare plant sites and rock pools. Create buffers and limit development around outcrops (Chafin 2007). Traffic from off-road vehicles appears to be the greatest impact at most sites. ATVs are clearly reshaping populations at Camp Meeting Rock, Rock of Ages, Wolf Rock, and other Georgia sites. Grazing from horses and cattle can also seriously impact the pool habitat and introduce exotics (e.g. at 40 Acre Rock). Pool use by Canada geese and bobcats was also observed; it is not clear if this activity could increase eutrophication in pools and lead to population declines. Many outcrops were also observed to be used as dump sites. Impacts from trash may lead to the leaching of chemicals in pools. Within the pools, the introduction of the exotics Ranunculus pusillus and Callitriche heterophylla appear to be placing competition pressure on Amphianthus pusillus, Isoetes melanospora, and Isoetes tegetiformans. Along the margins of the granite outcrop sites, Lonicera japonica and Ligustrum sinense appear to be the major invasive threats.

impact of exotic pest plants germination requirements

The recovery plan(1993)recommends: preservation of genetic stock from acutely threatened populations research on germination requirements