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Whitebark pine (Pinus albicaulis) trees occur in high-elevation environments and provide important habitat for many species, including grizzly bears, nutcrackers, and red squirrels. Yet, these grand trees are in demise across their distribution due to fire suppression, mountain pine beetles, and an introduced blister rust.
Due to the importance of whitebark pine, better resources are needed for interpreting the latest science and providing access to monitoring efforts. Learn more about whitebark pine, access a database of scientific literature about whitebark pine, and delve into the whitebark pine monitoring protocols and projects of the National Park Service's Greater Yellowstone Network Inventory & Monitoring Program at the Greater Yellowstone Science Learning Center site (under construction).
Whitebark pine is considered a keystone species in subalpine ecosystems because the survival of a large number of other species depends on its existence. It provides many ecosystem services: controlling runoff anderosion, influencing regeneration and succession, and providing a valuable food source.
Like most conifers, whitebark pine has wind-dispersed pollen. Seeds are dispersed by animals and birds, primarily the Clark's nutcracker (
).The nutcracker has a mutualistic relationship with whitebark pine, and it relies on seeds from the tree as its primary food source.
High-elevation, exposed sites near timberline
Western United States and Canada
Imperiled across their distribution due to fire suppression, mountain pine beetles, and an introduced blister rust
Grizzly Bear (Ursus arctos horibilis) [Photo: Jim Peaco, National Park Service]
The grizzly bear is an omnivore, eating both plants and animals. Approximately 80 to 90 percent of its diet is green vegetation, nuts, seeds, berries, and roots. In parts of their range, such as the Greater Yellowstone Ecosystem, grizzly bears depend so heavily on whitebark pine seeds that their survival has been linked to the presence of whitebark pine (Mattson and Reinhart 1997).
However, grizzly bears do not collect the seeds themselves; bears depend on red squirrels who collect the seed cones and store them in middens, which are piles of cones and debris that have accumulated over years of use (Koteen 2002; Mattson and Jonkel 1990; Mattson and Reinhart 1994). Grizzly bears will take cones from these middens, usually following squirrels to locate them (Mattson, Kendall and Reinhart 2001).
Whitebark pine seeds are large and more than 50% fat, providing a high-energy food source (Lanner and Gilbert 1994). In a good cone crop year, grizzlies will spend the fall feeding almost exclusively on whitebark pine seeds (Tomback, Arno and Keane 2001). Because female grizzlies rely on sufficient fat stores to get through both winter and reproduction (Mattson, Kendall and Reinhart 2001), female grizzly bears eat approximately twice the amount of whitebark pine seeds as male grizzlies (Mattson 2000).
Koteen, L. (2002). Climate Change, Whitebark Pine, and Grizzly Bears in the Greater Yellowstone Ecosystem. Wildlife Responses to Climate Change: North American Case Studies. S. S. a. R. TL. Washington, Island Press: 343-414.
Lanner, R.M. and B.K. Gilbert (1994). Nutritive value of whitebark pine seeds and the question of their variable dormancy. In: Schmidt, W. and Holtmeier, F.-K., compilers. Proceedings - International workshop on subalpine stone pines and their environment: The status of our knowledge. USDA Forest Service, Intermountain Research Station, Ogden, Utah: 206-211.
Mattson, D.J. (2000). Causes and consequences of dietary differences among Yellowstone grizzly bears. Ph.D. Dissertation. University of Idaho, Moscow.
Mattson, D.J. and C. Jonkel (1990). Stone pines and bears. In: Schmidt, W. and McDonald, K., eds., Symposium on Whitebark Pine Ecosystems: Ecology and Management of a High Mountain Resource. Ogden, UT: USDA Forest Service, Intermountain Research Station: 223-236.
Mattson, D.J. and D.P. Reinhart (1994). Bear use of whitebark pine seeds in North America. In: Schmidt, W. and Holtmeier, F.-K., compilers. Proceedings - International workshop on subalpine stone pines and their environment: the status of our knowledge. USDA Forest Service, Intermountain Research Station, Ogden, Utah: 212-220.
Mattson, D.J. and D.P. Reinhart (1997). Excavation of red squirrel middens by grizzly bears in the whitebark pine zone. Journal of Applied Ecology 34:926-940.
Mattson, D.J., K.C. Kendall and D.P. Reinhart (2001). Whitebark Pine, Grizzly Bears, and Red Squirrels. Whitebark Pine Communities: Ecology and Restoration. T. DF., A. SF. a. K. RE. Washington, Island Press: 121-136.
Tomback, D.F., Stephen F. Arno and Robert E. Keane (2001). The Compelling Case for Management Intervention. Whitebark Pine Communities: Ecology and Restoration. T. DF., A. SF. a. K. RE. Washington, Island Press: 3-25.
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