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LIMBER PINE COMMUNITIES
KEYWORDS
- limber pine communities, Pinus albicaulis, Pinus flexilis, population trends, whitebark pine communities
- GEOGRAPHIC DISTRIBUTION
- Alberta and British Columbia, Canada, Glacier National Park, MT, Grand Teton National Park, Montana, Waterton Lakes National Park, Wyoming, Yellowstone National Park
Status and Trends of Limber Pine Communities: The range of limber pine partially
overlaps with that of whitebark pine, both species have large, bird-dispersed seeds, and
both are highly susceptible to white pine blister rust, an exotic fungus. The two species
are so similar in appearance it is only possible to distinguish between them when cones
are present, yet they are more distant taxonomically than other species which are visually
dissimilar. 
While whitebark
pine has begun to receive research and management attention in recent years, little is
known about limber pine communities.
Limber pine is a 5-needled pine widely distributed in the mountains and foothills of the western United States and southern Canadian Rocky Mountains. Little is known about limber pine ecology and condition. Studies of whitebark pine in Glacier National Park, MT, led to concern about the high amount of mortality in limber pine stands. Like its cousin whitebark pine, it is highly susceptible to white pine blister rust. In 1995 and 1996, site characteristics, tree status and damaging agents were recorded in 81 limber pine stands extending from southern Alberta to eastern Idaho and northern Wyoming. Sampling was far from comprehensive but the results were consistent with the general pattern of limber pine tree status in this region. Limber pine mortality and blister rust patterns in the intermountain west of the US and Canada are documented in Kendall 1997, Kendall and Schirokauer 1997, Kendall et al. 1996c, Kendall 1994 and Kendall and Arno 1990.
In the areas sampled, limber
pine occurred on extremely xeric sites at lower and upper tree line. Lower treeline stands
were usually found in areas too dry for ponderosa pine, such as the east slopes of the
Beartooth Plateau and various island mountain ranges. Pure stands of limber pine were
commonly located on windswept, rocky ridges, whereas mixed stands were more common on
hillsides, usually with south-facing slopes. Occasionally, mixed stands of limber pine and
ponderosa pine, Douglas fir, or lodgepole pine were located on slopes with northern
aspects where soil moisture was higher. Whitebark pine was mixed with limber pine in many
stands sampled on the Blackfoot Indian Reservation and east side of Glacier National Park
in Montana.
Limber pine has suffered
extensive, heavy mortality and blister rust infection in northwest Montana and southern
Alberta (Table 1). On average, over a third of the limber pine is dead and about 75% of
the remaining live trees are infected with rust and 30% of the crown has been lost. Limber
pine is functionally extinct or endangered in most of the Greater Glacier Ecosystem, but
its health improves somewhat to the north and south. Mortality and blister rust incidence
rates were lower north of Waterton Lakes in the Porcupine Hills, Alberta. In southwest
Montana, northwest Wyoming, and adjoining areas of Idaho, limber pine mortality and
incidence of rust is low to moderate with a few hot spots of heavy infection. Although
blister rust incidence in limber pine stands in the Bighorn Mountains of north-central
Wyoming is generally low, high infection rates and significant mortality was found at
sites in the northeast and southwest corners. We found no rust in Craters of the Moon
National Monument in southern Idaho. When trees identified as "probably
infected" were included, rust infection rates rose for all areas, sometimes
substantially, as in the Porcupine Hills (Table 1).
Not all damage to limber pine trees was attributed to blister rust. In some stands with dead and dying trees or trees with thinning crowns or dead tops, we saw no definite cankers or other evidence of rust. Some of the defoliation was due to limber pine needle cast but a number of factors, such as severe climatic events, mistletoe, and/or mountain pine beetles, may have combined to cause the poor health observed.
Whitebark pine seeds are a well documented bear food but reports of bears feeding on limber pine seeds are scarce. We found evidence that bears ate limber pine seeds in the Porcupine Hills (2 scats) and in Waterton Lakes National Park, Alberta (1 scat). The scats were found in limber pine stands with no whitebark pine trees in the vicinity. Many limber pine trees we surveyed were short enough that bears could reach cones without climbing trees. Thus, limber cones were available to grizzly bears (poor climbers) without squirrels acting as intermediaries by cutting down cones.
Table 1. Preliminary data on the status of and effect of blister rust on limber pine (Pinus flexilus) stands sampled in 1995–96.
| Area sampled | Number of sample sites | Mean Mortality %1 (range) |
Mean Definite infection % (range) |
Mean Probable infection %2 (range) |
Mean crown kill %3 (range) |
| Bighorn Mtns., WY | 4 | 2 (0-6) |
22 (0-58) |
32 (4-68) |
4 (0-15) |
| Blackfoot Reservation, MT | 6 | 42 (0-68) |
53 (0-100) |
53 (0-100) |
27 (0-56) |
| Central Idaho | 2 | 0 | 0 | 0 | 0 |
| E. Front, MT | 2 | 21 (16-24) |
14 (4-27) |
30 (23-43) |
8 (7-9) |
| N.W. Wyoming | 13 | 10 (0-62) |
24 (0-78) |
28 (0-87) |
5 (0-19) |
| Porcupine Hills, Alberta | 4 | 14 (4-23) |
48 (43-57) |
76 (64-88) |
22 (12-28) |
| Grand Teton National Park, WY | 1 | 16 | 32 | 32 | 6 |
| Glacier National Park, MT | 22 | 39 (0-89) |
78 (0-100) |
80 (0-100) |
35 (0-80) |
| Yellowstone National Park, WY, MT, ID | 3 | 28 (4-410 |
1 (0-2) |
2 (0-6) |
0 (0-0) |
| Gallatin NF, MT | 4 | 37 (9-88) |
17 (0-39) |
24 (2-46) |
15 (13-17) |
| S.W. Montana | 11 | 19 (2-88) |
29 (0-89) |
33 (0-89) |
7 (0-19) |
| Waterton L. National Park, Alberta | 8 | 46 (26-85) |
85 (65-97) |
93 (81-98) |
33 (19-49) |
1 Includes mortality from all causes.
2 Includes trees which were probably, as well as, definitely infected with blister rust.
3 Average crown kill of all live limber pine trees.
Katherine Kendall katherine_kendall@usgs.gov
USGS-BRD
Science Center, c/o Glacier National Park
West Glacier, Montana 59936-0128
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Content Information Contact: katherine_kendall@usgs.gov
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U.S. Department of the Interior, U.S. Geological Survey
Northern Rocky Mountain Science Center, BOX 173492, Montana State University,
Bozeman, Montana, 59717-3492
Maintainer: mrblair@usgs.gov
Last Modified: 25 April 2003 11:22
URL:
http://nrmsc.usgs.gov/research/limber.htm