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Hurricane force wind velocities (>73 mi/hr) regularly occur on ridgetops occupied by high elevation white pines.

Photo tour

Aging Leaves

Pine shoot with some needle removal

Pine shoot with some needle removal to show the bud scale scars (at the lines); the numbers reflect the age of the needles formed on each segment of the twig.

Pines add new leaves on to the terminal of a growing twig each year. The leaves produced in any one year are called a "leaf cohort". Pines can retain leaf cohorts for many years (thereby being referred to as "evergreen").

High elevation white pines retain leaves for 5 to about 20 years, on average. Great Basin Bristlecone pine holds the record for the greatest leaf longevity - trees of that species can retain a leaf cohort for 40 years.

You can determine the age of a needle on a shoot by counting bud - scale scars back from the growing terminal. Each spring when the overwintering bud grows, the scales covering the bud leave a scar on the twig that looks like a series of horizontal lines across the twig. Each section of twig and the attached needles are produced in one year, and by counting back from the terminal (present year) you can estimate the year each twig segment and attached leaves were formed.

Rocky Mountain bristlecone pine shoot

Rocky Mountain bristlecone pine shoot.

The length of each cohort of needles is affected by the amount of water the tree had access to during the summer the needles expanded. The needles that expanded in a dry year tend to be shorter than those in a wet year. As a result, each cohort can have different length leaves - this is very obvious on the bristlecone pines.

Bark Beetles

Pitch tube on limber pinePitch tube on limber pine.

Bark beetles can live and breed in high elevation white pines. A beetle infested tree often dies. When the beetles burrow into the tree bark it stimulates the production of sap or pitch by the tree which can "pitch the beetle out" and prevent the beetle from colonizing the tree. A tree that has been challenged by the beetles often has "pitch tubes".

Limber pine cluster

Limber pine cluster with one tree attacked by bark beetles and not.

Note in this photo that only one of the limber pine trees in this cluster of trees was hit by the beetles.

(Link to tree clusters)

Bird damaged cones and Clarks Nutcracker

Clarks Nutcracker with pine seedClarks Nutcracker with pine seed.

Of the high elevation white pines, seeds of limber and whitebark pines do not have any wings and therefore cannot be effectively dispersed by the wind. Dispersal of these seeds is facilitated by birds, most notably the Clarks Nutcracker.

Limber pine conesLimber pine cones shredded by Clarks Nutcracker.

Birds of this species peck at the cones while they are still on the tree and extract the seeds. The birds can eat the seeds right then or they can put up to 150 seeds at a time in a pouch in the floor of their mouth. With the seeds in their pouch, the birds can transport the seeds up to 22 kilometers away and bury them in small caches of 3 - 5 seeds each, on average, to be retrieved and eaten later. In a year with good seed production a bird may cache up to 25,000 to 35,000 seeds and recovers many of those seed by means of a remarkable spatial memory.

Cluster of whitebark pine seedling

Cluster of whitebark pine seedlings that resulted from an abandoned Nutcracker cache.

Seeds in caches that are not retrieved may germinate to form clusters of seedlings

Bear sign

Grizzly bears and black bears are often part of high elevation white pine ecosystems.

Grizzly bear claw marks on whitebark pineGrizzly bear claw marks on whitebark pine tree.

There claw marks are frequently seen on the trunk of trees as seen here on whitebark pine in Yellowstone National Park.

Grizzly bear scat

Grizzly bear scat showing whitebark pine seedcoats.

The seeds of whitebark pine are also an important food source for Grizzly bears to prepare for the long winter. Pictured here is a clump of bear scat (photographed right after snowmelt) that is almost totally composed of whitebark pine seed coats - evidence that this bear was eating almost an entire diet of whitebark pine seeds the previous fall.





Cone Collecting

Wire cages on limber pine conesWire cages on limber pine cones to protect them from squirrels and birds.

We are often in competition with wildlife for cones and seed. To collect cones, often we must protect the cones and seeds during maturation from the wildlife using wire cages.

Using a pole pruner to collect bristlecone pine cones

Using a pole pruner to collect bristlecone pine cones.

When the seeds are mature, the cones are plucked from the tree. To retain viability of the seeds, they must be stored in cool to cold conditions.

Cone caches

Red squirrel

Red squirrel

Red squirrels cut down cones from the trees and make large piles (caches). The squirrels feed on the seeds through the winter.

Cone cache

Cone cache

The squirrels strip off each cone scale to reveal and eat the 2 seeds behind each scale. Bears raid these caches to obtain and eat the nutritious pine seeds.

Cones and seeds

Rocky Mountain bristlecone pine seedsRocky Mountain bristlecone pine seeds (left) and limber pine seeds (right).

Some of the high elevation white pines have winged seeds and some have wingless seeds. Winged seeds can disperse from the cones in the wind. Wingless seeds cannot be dispersed far from the cone - producing tree and primarily dispersed by birds (such as the Clarks Nutcracker). Winged seeds can also be dispersed by birds.

Rocky Mountain bristlecone pine krummholA Rocky Mountain bristlecone pine krummholz with current year and last year cones.

Even trees growing at the alpine treeline can produce cones and viable seed. The open cones shed seed the previous year and the closed cones are still maturing and will shed seed later in the season after this photo was taken. Whitebark pine cones never open; there seed must be extracted from the cones by birds.


Facilitation is when one object or organism positively affects the success of another organism. Facilitation can occur in any ecosystem and is common in the transition zone between the alpine and forested life zones.

Whitebark pine tree

Whitebark pine tree established in the lee of a rock.

Subalpine fir and limber pine

Subalpine fir and limber pine established in the lee of a Rocky Mountain bristlecone pine at treeline.

Subalpine fir and limber pine only occur on this site when in the protection of bristlecone pine. As a result, bristlecone pine is extending the elevational range of these species on this site.

Douglas fir

Douglas fir established in the protection of a limber pine in the forest - grassland transition zone.

Harsh habitats

Limber pine

Limber pine growing in the crack of a large rock.

Limber pine

Limber pine growing on a rock outcrop

Tree clusters

Limber and Ponderosa pine tree cluster

Limber and Ponderosa pine tree cluster.

As a consequence of the animal seed caching, where multiple seeds are cached in one spot, often several of the seeds germinate and become established to for a cluster of trees. For this cluster, the bird must have collected seed from limber pine and ponderosa pine cones since 2 of the stems are limber pine and one (right) is a ponderosa pine.

This clustered growth form is common for the bird - dispersed species such as whitebark pine and limber pine.

Rodent Damage

Rodents often gnaw on blister rust cankers because of the sweet sap produced by the tree in the area of the canker. Porcupines and other larger animals can also eat bark of healthy trees

Rodent gnawing of a blister rust boleRodent gnawing of a blister rust bole canker on limber pine.

Rodent gnawing of a blister rust

Rodent gnawing of a blister rust branch canker on limber pine.


Seedlings of high elevation white pines require high light environments and often become established in areas that were recently burned. Burns reduce competition from understory (ground level) plants and offer amble sunlight for the seedlings since the overstory (tree) canopy has been removed by the fire.

Six year old whitebark pineSix year old whitebark pine seedling burn that occurred 12 years ago.

Bristlecone pine seedlingOne month old bristlecone pine seedling in a burn that occurred 2 year ago.

Bristlecone pine seedling One month old bristlecone pine seedling in an open area of an unburned forest.

Limber pine seedling

Newly emerged limber pine seedling with its seed coat still attached.

Strip barking

Strip barking is a condition that is caused by partial cambial dieback. It can refer to a tree where the cambium has died leaving a strip of exposed wood that extends from a dead branch down to a dead root or to the condition when all of the cambium has died leaving only a thin strip of live bark that extends from one live branch down to one live root. This condition is most common on very old trees. The factors that cause the initial partial cambial dieback and the benefits of this growth form to survival are still being studied by scientists.

Strip barked bristlecone pine

Strip barked bristlecone pine.

Strip barked bristlecone pineStrip barked bristlecone pine.

Early stages of strip barkingDiagram of the early stages of strip barking.

Later stages of strip barking

Diagram of the later stages of strip barking.


Numerous species of animal live and depend on high elevation white pine ecosystems.

Baby rabbits in a Rocky Mountain bristlecone pine forest.

Moose in a whitebark pine forest

Moose in a whitebark pine forest.

Wind sculpted trees

High elevation white pines often grow on exposed ridges. Wind and blowing snow can damage tender growing points on twigs and branches. Continual pruning of the tree canopies by the wind and wind - blown particles and the successful growth of twigs and branches in wind - protected areas result in the dramatic wind - swept tree forms. Near the alpine zone, these trees stunted, mat - like forms called krummholz. Krummholz can serve to capture leaves and other particles and can affect the chemical composition of the soil underneath them. The prevailing wind is from the left in each of these photos.

Rocky Mountain bristlecone pine near treelineRocky Mountain bristlecone pine near treeline.

Rocky Mountain bristlecone pine krummholzRocky Mountain bristlecone pine krummholz in the alpine - forest transition zone.

Rocky Mountain bristlecone pine krummholz

Rocky Mountain bristlecone pine krummholz in the alpine - forest transition zone.

Litter accumulation

Litter accumulation under a bristlecone pine krummholz.

Artistic forms

The high elevation white pines are long - lived and grow in harsh habitats; as a result they can form beautiful forms. The habitats tend to be dry which delays decomposition such that dead snags can persist for many years.

Frost covers bristlecone pine

Frost covers bristlecone pine shoot in the morning

Uprooted bristlecone pineUprooted bristlecone pine.


Uprooted bristlecone pine

Uprooted bristlecone pine.

Bristlecone in snow.

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