Plethodon larselli

Pelletier et al. (2015) provided a study of historical species distributions and suggested that this nominal species is composed of two independently evolving lineages (Frost 2020). See also Howard et al. (1983) for information on genetic variation.

This species is of concern due to its small range in Oregon and Washington, fragmented habitat, and ongoing threats from timber management. Although many populations are on federal land and several occurrences are protected, moderate threats from habitat alteration exist elsewhere.

The Larch Mountain salamander occurs in the Columbia River Gorge in southern Washington and northern Oregon (USA), and discontinuously northward in the Cascades to central Washington (to at least the Snoqualmie Pass-Kachess Lake area) (Leonard et al. 1993, Petranka 1998, Stebbins 2003). Elevational range extends to around 4,200 feet (Crisafulli et al. 2008). The southern end of the range is roughly defined by the towns of Hood River and Troutdale, Oregon, although there are two disjunct records further south in the Mount Hood National Forest (ORBIC 2022). In Washington, the species occurs in the Western Cascades Physiographic Province, with the main distribution along a 58-km stretch of the Columbia River Gorge; additional, isolated populations occur in the Cascade Range. The species is documented in Clark, Cowlitz, Skamania, Pierce, Lewis, King, Klickitat and Kittitas Counties in Washington and Multnomah, Hood River, and Clackamas counties in Oregon (ORBIC 2022). Population distribution within the range is patchy (Hallock and McAllister 2005).

145 total documented sites in Oregon and Washington, though some of these sites are close to one another and would be combined into single element occurrences (Crisafulli et al. 2008). Populations in most of these sites are expected to be extant. There are approximately 16 populations in Oregon and at least 25 populations in Washington (ORBIC 2022).

Habitat loss, degradation, and disturbance are the primary threats to this species (Crisafullli et al. 2008). Rock mining and disturbance of talus alters microhabitat for this species (Crisafulli et al. 2008).Threatened by logging (changes microclimate and resources of talus slopes) and by use of talus for road construction; any ground-disturbing activity or land use that changes the moisture regimes and permeability of inhabited rocky substrates, such as overstory tree removal and gravel removal, may threaten populations (Herrington and Larsen 1985, Aubrey et al. 1987, Pfrender 1993, Leonard et al. 1993, Petranka 1998, Hallock and McAllister 2005). Not found in clear cut forests (Crisafulli et al. 2008). Tree removal may result in loss of moss ground cover, desiccation of sites, and substrate disturbance (Crisafulli et al. 2008). Chemical applications (i.e., herbicides, pesticides, fertilizers) may affect salamanders directly due to toxicity or indirectly due to loss of prey-base (Hallock and McAllister 2005, Crisafulli et al. 2008). Limited dispersal ability is suspected but not documented (Crisafulli et al. 2008). This species is of moderate-to-high vulnerability to climate change (Washington Department of Fish and Wildlife 2022). Longer periods of warmer, drier weather will limit the species' ability to be above ground. However, Nottingham and Pelletier (2021) predict suitable habitat will expand under climate change for this species.