Threats to Relict Sample Clauses

Threats to Relict. Leopard Frog Associated with the Five Listing Factors‌ Factor 1. Present or Threatened Destruction, Modification, or Curtailment of Habitat or Range‌ Water diversions and groundwater development may be a continuing threat to relict leopard frog conservation where historical populations have been extirpated or their habitats altered due to diversion of water from streams or wetlands for activities associated with livestock grazing, agriculture, urban development, and other uses. Because of legal appropriations under applicable water laws, and land use practices on public, private, and tribal lands, water diversions continue to occur and may be problematic for relict leopard frog conservation and management of occupied or historical leopard frog habitats. Extant populations are restricted to perennial desert springs along the Virgin and Colorado river drainages. Substantial leopard frog habitat in the historical range of the relict leopard frog has been destroyed or modified by activities such as spring capping and diversions and the construction of dams and reservoirs. Modifications have not only changed the amount and quality of habitat available for relict leopard frogs, but may also have created habitat for and promoted introduction of nonnative predators (Sredl et al. 1997). In addition to local spring and stream modifications, aquifer overdrafting in areas that affect relict leopard frog habitat may be a significant threat, because these aquifers may be limited in their ability to recharge. Habitat heterogeneity is thought to be an important component of relict leopard frog aquatic and terrestrial environments (Xxxxxxxx 1987; Xxxxxxxx and Xxxxx 1994; Xxxxx 0000). Unchecked by disturbance, both native and nonnative plant species can quickly form uniformly dense stands of vegetation, eliminating open habitat and resulting in the disappearance of varied habitat structure. In addition to forming dense stands of vegetation, aggressive nonnative species such as tamarisk (Tamarix sp.) and tall whitetop (Lepidium latifolium) can irreversibly alter plant and insect communities, soil chemistry, and disturbance regimes. Effects of livestock grazing on relict leopard frog populations may be positive and negative (Xxxxxxxx 1988; Xxxxx and Xxxxxxxx 1998; Xxxxx and Xxxxxx 1998). While grazing has attributed to maintaining open areas in spring systems, high levels of grazing can negatively impact amphibian habitat by removing bankside cover, increasing ambient ground ...