Trillium reliquum

Overabundance of White-tailed Deer (Odocoileus virginianus) presents a significant threat to the species. White-tailed Deer herbivory has been shown to reduce the rate of transition to reproductive adult size classes within overgrazed subpopulations (Leege et al. 2010). Habitat degradation caused by feral hogs (Sus domesticus) has been documented to negatively impact several species of Trillium (Bratton 1974). Six subpopulations of Relict Trillium are noted to have extensive habitat degradation associated with rooting of feral hogs (U.S. Fish and Wildlife Service 2015). The use of fire in forest management efforts, particularly those aimed at management of red-cockaded woodpecker habitat, may have adverse impacts on Relict Trillium subpopulations. The timing of prescribed fire, which generally occurs in winter and early spring, may be especially detrimental to recruitment (U.S. Fish and Wildlife Service 2015).

Competition with several introduced plant species impacts subpopulations on both public and private land. Introduced species noted to impact subpopulations include Nepalese Browntop (Microstegium vimineum), Japanese Honeysuckle (Lonicera japonica), English Ivy (Hedera helix), Kudzu (Pueraria lobata), Chinese Privet (Ligustrum sinense), and Trifoliate Orange (Poncirus trifoliata) (U.S. Fish and Wildlife Service 2015). At present, efforts to control competing invasive plants are inadequate within the species’ range. Cutworm infestations and fungal diseases observed in South Carolina, may present a threat to the broader population should these factors spread (U.S. Fish and Wildlife Service 2015). Additional study is needed to determine the severity of these threats.

These threats are likely to compound one another leading to synergistic patterns of decline. Urbanization, logging, and habitat fragmentation is likely to exacerbate overabundance of the white-tailed deer population by increasing carrying capacity within mosaic environments, and increasing areas where public safety limits hunting pressures (Russell et al. 2001). Herbivory by deer is also likely to be increased due to loss of suitable forage caused by the spread of inedible invasives including Nepalese Browntop, and Trifoliate Orange.

Collection pressures have caused declines in some subpopulations. Land management practices in privately held areas have caused increased erosion in creeks resulting in loss of some plants in subpopulations on floodplains.

The species was listed as federally Endangered in 1988 under the Endangered Species Act (U.S. Fish and Wildlife Service 2015). Several of the 72 known subpopulations occur in protected areas including seven in Georgia, and two in South Carolina which are completely within publicly owned land holdings. In addition, six subpopulations occur partially on publicly owned land (four in Georgia, and one in each of Alabama, and South Carolina) (U.S. Fish and Wildlife Service 2015). Some occurrences on private land are considered secure due to agreements between land owners and The Nature Conservancy. Subpopulations on public land are not subject to disturbance due to development and clear cutting, but are inadequately protected against exotic plants and animals (U.S. Fish and Wildlife Service 2015). Very limited protections exist for plants occurring on private land under the Endangered Species Act. As Relict Trillium is under no state level protection within its range, it is at risk of habitat loss associated with development at all sites occurring on private land. Cooperation agreements with land holders which focus on relocation efforts have been successful. However, site level protections on private land have had limited effectiveness.

Systematic and comprehensive population surveys suggest that some requirements for de-listing the species under the Endangered Species Act have been met (Caspary and Rickard 2016) and de-listing is likely in the near future.

Relocation efforts have prevented the loss of several thousand plants at sites in Georgia and South Carolina that were subsequently destroyed (U.S. Fish and Wildlife Service 2015). The success of these transplantation efforts has been mixed, however, with some relocated subpopulations subsequently declining due to improper management, and no recruitment having been observed in areas where adequate protection has been established.