Status of Whitebark Pine in Crater Lake National Park, Oregon, 2000
INTRODUCTION
Natural History
Whitebark pine is a long-lived and hardy tree able to thrive at sites which experience harsh climatic forces. The pine’s large and nutritious seeds are prized by Park wildlife including Clark’s nutcrackers, black bears, and red squirrels. Elk and grouse use trees for shelter. Their canopies support arboreal lichens and understory flora such as woodrush and currants. Whitebark pine also stabilize soil and regulate snowmelt.
Although blister rust occurs on all five-needled pines, such as western white (Pinus monticola) and sugar (P. lambertiana), whitebark pine is by far the most susceptible. Spores of the fungus arrive in moisture-laden air and infect five-needled pines and currant bushes. It is not fatal to currants, but once the spores reach the needles of whitebark pine, the infection spreads to branches. Within a year or two, a canker is formed by the fruiting bodies thus destroying the tree’s living tissue in the vicinity of the infection. If the infection is at or near the main stem of the tree, topkill will occur, seriously threatening the tree’s ability to survive. Often, other damaging agents such as mountain pine beetle (Dendroctonus rufipenis), wind, and alternate fungi take advantage of the injured tree and contribute to its death. White pine blister rust has proven very lethal in other parts of North America where up to 90 percent mortality has been estimated (Kendall 1994).
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