The status of whitebark pine along the Pacific Crest National Scenic Trail on the Umpqua National Forest.

Abstract

Because of concern over widespread population declines, the distribution, stand conditions, and health of whitebark pine (Pinus albicaulis Englem.) were evaluated along the Pacific Crest National Scenic Trail on the Umpqua National Forest. Whitebark pine occurred on 76 percent of the survey transects. In general, whitebark pine was found in stands with lower overall densities and fewer late-seral species, particularly Shasta red fir (Abies magnifica var. shatensis A. Murr.) and mountain hemlock (Tsuga mertensiana [Bong.] Carr.). Whitebark pine stocking differed widely, from less than 1 up to 24 percent of the trees on transect plots. Most whitebark pines (87 percent) were less than 5 m tall. Of all whitebark pine encountered, 44 percent were alive and healthy, 46 percent were alive but infected by Cronartium ribicola (J.C. Fisch) (cause of white pine blister rust), and 10 percent were dead. Two-thirds of the mortality was due to white pine blister rust. Mountain pine beetle (Dendroctonus ponderosae Hopkins) alone accounted for 13 percent of the mortality, whereas evidence of mountain pine beetle was found with white pine blister rust on 18 percent of the dead whitebark pines. White pine blister rust affected trees in all but the largest size class; 70 percent of the whitebark pines greater than 1.5 m tall and less than 7.6 cm diameter at breast height (d.b.h.) were infected. Most (92 percent) of infected whitebark pines had bole cankers or cankers within 15 cm of the bole. No cones were observed on whitebark pines in any of the survey plots. Whitebark pine was common in centers of laminated root rot (caused by the fungus Phellinus weirii (Murrill.) R.L. Gilbertson) where substantial canopy openings were found. In these centers, whitebark pine contributed 73 percent of the large tree stocking. The results of this survey constitute a reference condition for whitebark pine that can be used to assess change in its status in this part of southwest Oregon. Measures to reduce the impacts of disease and bark beetles and to maintain whitebark pine populations are discussed.

The distribution and incidence of white pine blister rust in central and southeastern Wyoming and northern Colorado

“…Overall, approximately 26% the recently killed limber pine in this study were infected by WPBR. Other studies in more northern and western North American areas have found higher total levels of mortality, including approximately 20% of whitebark pine in British Columbia with from 50% to less than 5% associated with WPBR (Campbell and Antos 2000;Zeglen 2002), 10% of whitebark pine in Oregon (Goheen et al 2002), and 8.7% of limber and whitebark pines in the Intermountain West (Smith and Hoffman 2000). Our lower level of mortality (5%) is most likely a reflection of the shorter time of exposure to rust in our study areas.…”

Response of high-elevation limber pine (Pinus flexilis) to multiyear droughts and 20th-century warming, Sierra Nevada, California, USA

“…6. Whereas significant mortality in high-elevation whitebark pine forests has resulted from non-native white pine blister rust, increasingly mountain pine beetle related mortality is also being observed Powell 2001, 2005;Goheen et al 2002;Waring and Six 2005). (A) Live tree response to water year precipitation and minimum temperature.…”

“…Conditions at high elevations generally have been less conducive to extensive insect and disease outbreaks than at lower elevations. Aside from blister rust, which has not been observed as a significant problem in the eastern Sierra Nevada, observations of scattered mortality related to mountain pine beetle (Dendroctonus ponderosae Hopkins) are being reported in other subalpine forests of the West, although these generally have been in stands below 2500 m Powell 2001, 2005;Goheen et al 2002;Waring and Six 2005). The most extensive dieback in subalpine forests of western North America in recent decades is occurring as a result of non-native white pine blister rust (Kendall and Arno 1990).…”

Current health issues and management strategies for white pines in the western United States and Canada

“…(2004) observed that plot‐level incidence in northern Idaho ranged from 50 to 96% for mature whitebark pine and 32 to 92% for immature whitebark pine. In a 1998 survey along Oregon’s Cascade Crest, G oheen et al. (2002) observed that about half of the white pine were infected.…”

“…Kegley et al (2004) observed that plot-level incidence in northern Idaho ranged from 50 to 96% for mature whitebark pine and 32 to 92% for immature whitebark pine. In a 1998 survey along OregonÕs Cascade Crest, Goheen et al (2002) observed that about half of the white pine were infected. In the Blue Mountains of northeastern Oregon, Erickson et al (2007) examined three, isolated, highelevation populations of whitebark pine (4000 trees sampled); blister rust incidence was 27, 64 and 73%, respectively.…”