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Special Status 

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BLM Wyoming has two species that garner special attention: the Whitebark pine and the Limber pine.


Whitebark Pine (Pinus albicaulis)

Growing where other trees do not, whitebark pine is the iconic high elevation pine of the Rocky Mountains. BLM Wyoming manages the farthest eastern and southern populations of this tree species.

     Whitebark pine.
Whitebark pine is a hardy conifer that tolerates poor soils, steep slopes, and windy exposures and is found at alpine tree line and subalpine  elevations throughout its range.  It grows under a wide range of precipitation amounts, from about 20-100 inches per year. Whitebark pine may occur as a climax species, early successional species, or seral (mid-successional stage) co-dominant associated with other tree species.  Although it occurs in pure or nearly pure stands at high elevations, it typically occurs in stands of mixed species in a variety of forest community types.

It is a slow-growing, long-lived tree with a life span of up to 500 years and sometimes more than 1,000 years.  It is considered a keystone, or foundation species in western North America where it increases biodiversity and contributes to critical ecosystem functions.  As a pioneer or early successional species, it may be the first conifer to become established after disturbance, subsequently stabilizing soils and regulating runoff.  At higher elevations, snow drifts around whitebark pine trees, thereby increasing soil moisture, modifying soil temperatures, and holding soil moisture later into the season.  These higher elevation trees also shade, protect, and slow the progression of snowmelt, essentially reducing spring flooding at lower elevations.  Whitebark pine also provides important, highly nutritious seeds for a number of birds and mammals.

These trees are capable of producing seed cones at 20–30 years of age, although large cone crops usually are not produced until 60–80 years.  Like many other species of pines, whitebark pine exhibits masting, in which populations synchronize their seed production and provide varying amounts from year to year.  During years with high seed production, typically once every 3–5 years, seed consumers are satiated, resulting in excess seeds that escape predation.  Whitebark pine seed predators are numerous, and include more than 20 species of vertebrates including: Clark’s nutcracker, pine squirrels, grizzly bears, black bears, Steller’s jay, and Pine Grosbeak.  The Whitebark pine has co-evolved with seed predators and has several adaptations, like masting, that has allowed the species to persist despite heavy seed predation.

The U.S. Fish and Wildlife Service issued their 12 month finding on a petition to list whitebark pine as a threatened or endangered species on July 19, 2011 in Federal Register Volume 76, Number 138.  The finding was that of “warranted but precluded,” with a Listing Priority Number (LPN) of 2. This LPN is the highest a species can receive and not be listed.

BLM Wyoming was the first state office to put whitebark pine on their Special Status Species list.  BLM Wyoming was also the first state to develop specific management guidelines for whitebark pine.


Limber Pine (Pinus flexilis)

Limber Pine.
Limber pine grows across the widest elevational range of any conifer in the Rocky Mountains, ranging from approximately 5,250 feet (1,600 m) to almost 11,000 feet (3,300 m) (Schoettle and Rochelle 2000).  This elevational range increases when the isolated populations, like one found in North Dakota at 2,850 feet (869 m), into consideration.

Assessing Limber Pine Stand Conditions Poster.
Assessing Limber Pine
Stand Conditions after
Mountain Pine Beetle
Outbreaks in the
Rocky Mountains Poster.

Wyoming has more limber pine than any other state (approximately 500,000 acres) and BLM Wyoming manages more of this species (210,000 acres) than any entity in the state.  Limber pine is found from high elevation BLM-administered lands growing with whitebark pine, to the ecotones dividing the woodlands from grass/shrub ecosystems.  Very little is known about the complex interactions at the lower treeline ecotones and the tree's relationships to wildlife and hydrology.

 

BLM Wyoming is partnering with Colorado State University and the U.S. Forest Service on the first regional assessment of limber pine in the Rocky Mountain Region.