Current mountain pine beetle activity in whitebark pine ecosystems in the Greater Yellowstone Ecosystem is unprecedented in extent and severity. Dynamics among beetles, white pine blister rust, and climate change are placing this foundation species in a precarious state. Stand- and tree-level data was recorded to quantify how the severity of rust and the presence of an alternate host influence the susceptibility of whitebark to selection by the beetle. Data reveal that 52% of whitebark sampled were dead, 70% attacked by the beetle, 85% infected with rust, and 61% were afflicted with both. Beetle activity was lower than expected in trees with low severity blister rust and increased significantly in trees with high rust severity. On sites with two potential host species, whitebark pine is preferentially selected over lodgepole pine. This work reveals that blister rust increases whitebark selection probability by, and that lodgepole pine are not the preferred host of, the mountain pine beetle. The interaction between blister rust and mountain pine beetle, and the preference for whitebark pine may enhance whitebark pine mortality, population decline, and alter whitebark demography and the ecological processes to which these trees are critical.
Available at: http://works.bepress.com/daniel_tinker/2/