Pacific Southwest Research Station

Restoration strategies for whitebark, western white, and sugar pine in the Lake Tahoe Basin: ecological and epidemiological considerations

Principal Investigators:
Detlev Vogler, Pacific Southwest Research Station, Institute of Forest Genetics
Patricia Maloney, University of California, Davis
Annette Delfino‐Mix, Pacific Southwest Research Station, Institute of Forest Genetics

Proposal [pdf]

Final Report [pdf]

Abstract

Links with ecosystem health, resource conservation (vegetation, soil, water), and biological diversity are central to the health of Lake Tahoe. The white pine species – whitebark (Pinus albicaulis), western white (P. monticola), and sugar pine (P. lambertiana) are important components in low to upland forest communities. Interactions among anthropogenic disturbances such as historical logging and fire suppression, an exotic pathogen (Cronartium ribicola, cause of white pine blister rust [WPBR]), and climate‐driven outbreaks by Dendroctonus ponderosae (mountain pine beetle) have significantly affected populations of white pines in lower montane, upper montane and subalpine forests. White pine blister rust is one of the greatest threats to white pine sustainability and survival.

In the Lake Tahoe Basin this invasive pathogen is significantly affecting recruitment potential and survival of small and intermediate-sized trees. Such adverse demographic effects can have long-lasting consequences on population structure and dynamics. Comstock era logging, in some locations, has reduced effective population numbers and genetic variation of sugar pine. Both influences (i.e., WPBR and historical logging) can significantly affect how these species respond to other stressors, such as global climatic change. Strong evidence of negative population and genetic effects warrants white pine restoration in the Lake Tahoe Basin. Mitigating anthropogenic influences will require restoring effective population numbers, deploying WPBR‐resistant material, 'facilitating' recruitment, enhancing genetic variation, and planting drought‐tolerant genotypes.