First Lead for December 2004

More Seasons for Sugar Pines?

The holiday season brings with it the pungent fragrance of evergreen boughs and pine cones. The stately, long-coned sugar pine in the Sierra Nevada of California is such a seasonal emblem. But an exotic fungal disease, white pine blister rust, has caused declines in this and other five-needled pines throughout North America. Long-term data documenting the effects of this disease of concern and another stressor, fire exclusion, are rare, however. Now new research sheds light on the prognosis for the survival of the sugar pine in the Sierra Nevada. Using a unique long-term data set that documents 2,168 sugar pines over 15 years at several sites in the Sierra Nevada, researchers have found that all populations had high frequencies of infected trees; along with white pine blister rust, a large number of tree deaths were associated with crowding in these stands. Computer models indicated that most of these populations are slowly declining. However, while the populations appear to be compromised, they are buffered against rapid declines due to relatively high survivorship of large individuals. The use of blister rust-resistant genotypes and prescribed fire, two strategies already being used the Sierra Nevada to increase sugar pine establishment, have the potential of greatly aiding the recovery of this species. A National Park Service image of a mature sugar pine in Sequoia National Park is online at http://www.usgs.gov/newsroom/images/sugar_pine_nps_300res.jpg . For more, contact Phil van Mantgem at 559-565-3179 or pvanmantgem@usgs.gov.