Emerald Bay at Lake Tahoe. (photo Brant Allen/UC Davis TERC)
Emerald Bay at Lake Tahoe. (photo Brant Allen/UC Davis TERC)

Tahoe State of the Lake: Heritage Aspens and the Threat of White Satin Moth

The annual Tahoe: State of the Lake report, by the UC Davis Tahoe Environmental Research Center, presents data from 2018 regarding lake clarity, temperature, snowpack, invasive species, algae, nutrient loads and more, all in the context of the long-term record. The report notes, “Climate change is expected to impact all aspects of the Tahoe basin in the coming decades.”

While much of the report is about the state of the lake itself, an interesting component is the severe defoliation that many aspen stands are facing due to white satin moth.

From the report:

In 2011, white satin moth (Leucoma salicis) was first detected in North Canyon within the Lake Tahoe Nevada State Park. The moth’s (caterpillar’s) preferred hosts are native aspen trees (Populus tremuloides). Since 2011, the moth has spread northward and southward. Currently, there are numerous aspens stands that are experiencing severe defoliation as a result of these moths.

Aspen treesWhite satin mothWhite satin moth


Some of these highly defoliated stands are in heritage sites that document the rich history of Basque sheepherding and resource management in the Lake Tahoe Basin.

The TERC Forest and Conservation Biology team has been surveying stands around the Lake Tahoe Basin. Through this process they have identified the presence of the moth in a new location on the west shore — in the lower Blackwood Canyon area.

Researchers are quantifying levels of defoliation in aspen stands throughout the Lake Tahoe basin, as well as examining host chemistry which may be an indicator of white satin moth susceptibility or tolerance. Additionally, they will be developing early detection monitoring and conservation strategies for aspens in the basin.

More information:

Information on tree loss and restoration in the Sierra Nevada and other forests, Plant Sciences, UC Davis

  • The California Tree Mortality Data Collection Network, July 2019.
  • Thinning forests, prescribed fire before drought reduced tree loss. June 2019.
  • Sequencing brings modern tools to redwood conservation efforts. April 2019.
  • Genome project will restore health of coast redwood and giant sequoia forests. October 2017.
  • Bristlecone pine trees in the Great Basin are losing the game of leapfrog with the limber pine. September 2017.
  • How much drought can a forest take? Aerial tree mortality survey. January 2017.
  • High-severity wildfires complicate natural regeneration for California conifers. December 2016.
  • Fighting fire in a warmer world, October 2016.
  • Genome sequencing may save California’s legendary sugar pine. December 2015.
  • After California wildfires, Southern plant species are on the rise. August 2015.

(Article by Ann Filmer, Plant Sciences, UC Davis; August 2, 2019.)

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