Trillium persistens

The primary threat to the species is habitat degradation caused by forest clearance associated with construction and timber extraction. This has had documented negative impacts on subpopulations within the species’ range (U.S. Fish and Wildlife Service 2011). Forest clearance aids the spread of invasive species including Kudzu (Pueraria montana) and Japanese Honeysuckle (Lonicera japonica), resulting in further Persistent Trillium population declines and extended recovery times (U.S. Fish and Wildlife Service 2011). Threats posed by timber harvest have been largely mitigated as a result of voluntary conservation agreements made with landowners, and the purchase of land by the Georgia Department of Natural Resources (U.S. Fish and Wildlife Service 2011). English ivy (Hedera sp.) is present within the Talullah Gorge State Park and may present a substantial threat to Persistent Trillium within its entire range.

Disturbance caused by recreational usage of the species’ habitat (primarily trampling) is unlikely to impact the population as it occurs on steep, inaccessible slopes within protected areas (U.S. Fish and Wildlife Service 2011). Some efforts have been made to alleviate pressure in areas with high traffic and, at present, disturbance associated with recreational activity is not thought to present a significant threat.

The invasive Hemlock Woolly Adelgid (Adelges tsugae) may negatively impact the species by causing declines in Eastern Hemlock overstories (NatureServe 2019). As with forest clearance, die-offs of hemlock may result in increased competition with invasive plants, exacerbating population declines (U.S. Fish and Wildlife Service 2011).

Though predation by White-tailed Deer (Odocoileus virginianus) is a threat to several other species of Trillium in the eastern United States (Dávalos et al. 2014, Knight et al. 2009, Rooney and Gross 2003), it is unlikely to present a major threat to Persistent Trillium given the low densities of White-tailed Deer within the species’ range, and the steep slopes of its preferred habitat which are relatively inaccessible (U.S. Fish and Wildlife Service 2011).

Historical habitat losses caused by dam construction likely resulted in losses of large tracts of suitable habitat (NatureServe 2019). No additional dams have been proposed in the area and the ongoing threat to extant subpopulations is thought to be minimal.

Since 1978, the species has been listed as Endangered at the federal level, and is protected on public lands throughout its range (U.S. Fish and Wildlife Service 1984). At present, there is no indication that the species’ status is likely to change (U.S. Fish and Wildlife Service 2011). Since 1993, much of the species’ range (probably encompassing 75% of the total population) has also been under the protection of the Tallulah Gorge State Park, which provides adequate protection against most threats to the species (U.S. Fish and Wildlife Service 2011). An ex-situ subpopulation of 20-30 plants has been maintained at the Georgia State Botanical Garden in Athens, Georgia since 1983 (U.S. Fish and Wildlife Service 2011). Though the process is labour and cost intensive, establishment of additional ex-situ subpopulations is recommended to protect the species against stochastic events that may impact its restricted range.

The range of the species is well established, however, additional population monitoring within this range is highly recommended to better determine population trends. In addition, genetic studies are needed to determine the substructure of the population, particularly in light of the high effective subpopulations needed to sustain population stability. Continued maintenance of a low White-tailed Deer population as well as control of invasive competitors, namely Japanese Honeysuckle (L. japonica), Kudzu (P. montana), and English Ivy (Hedera sp.) are crucial to the continued survival of the species (U.S. Fish and Wildlife Service 2011). These efforts are especially important within forest edge environments along utility rights-of-way and roadsides.