Pinus flexilis Woodland Alliance
Limber pine woodland
Limber pine woodland
USDA Ecological Section Map
Summary Information
- Primary Life FormTree
- Elevation2200-3350 m
- State RarityS3.2
- Global RarityG5
- DistributionCAN: AB, BC. USA: CA, CO, ID, MT, ND, NM, NV, OR, UT, WY (NatureServe)
- Endemic to CaliforniaNo
- Endemic to California Floristic Province and DesertsNo
- Date Added1995/11/01
Characteristic Species
Pinus flexilis is dominant in the tree canopy with Abies concolor, Pinus albicaulis, Pinus balfouriana, Pinus contorta ssp. murrayana, Pinus jeffreyi and Pinus longaeva. Shrubs include Artemisia tridentata, Cercocarpus ledifolius, Chrysolepis sempervirens, Chrysothamnus viscidiflorus, Eriogonum umbellatum or Ribes cereum.
Vegetation Layers
Trees < 18 m; canopy is open. Shrubs are infrequent or common. Herbaceous layer is sparse.
Membership Rules
- Pinus flexilis > 50% relative cover in the tree canopy (Keeler-Wolf et al. 2003b, Klein and Evens 2005).
- Pinus flexilis > 55% relative cover or > 25% absolute cover in the tree canopy; no tree species with higher cover (Thomas et al. 2004).
Habitats
Most extensive on upper slopes, crests, ridges, summits, upper high-elevation slopes to timberline. Soils are commonly granitic derived, loose, well drained, and often rocky.
Other Habitat, Alliance and Community Groupings
| MCV (1995) | Limber pine series |
| NVCS (2009) | Pinus flexilis woodland alliance |
| Calveg | Limber pine, Subalpine conifers |
| Holland | Limber pine forest |
| Munz | Red fir forest |
| WHR | Subalpine conifer |
| CDFW CA Code | 87.160.00 |
National Vegetation Classification Hierarchy
| Formation Class | Mesomorphic Tree Vegetation (Forest and Woodland) |
| Formation Subclass | Temperate Forest |
| Formation | Cool Temperate Forest |
| Division | Western North America Cool Temperate Forest |
| Macro Group | Rocky Mountain Subalpine and High Montane Conifer Forest |
| Group | Western Cordilleran xeric subalpine coniferous forest and woodland |
Remarks
Pinus flexilis is a slow-growing, long-lived tree that attains 18 m in height and may live 1000 years. Trees begin bearing cones at 20-40 years, and they have large seed crops every 2-4 years. Small mammals and birds, especially Clark’s nutcrackers and pinyon jays, disperse seeds from open cones. Seedling establishment occurs from cached seed near trees and rocks. Trees are shade intolerant. Individuals may be erect trees or dwarfed or contorted krummholz. Trees commonly have two or more trunks that often partially fuse at the base, which may be one genetic individual with stems rising from layering or several individuals rising from cached seeds (Johnson 2001, Steele 1990).
Pinus flexilis grows in many mountain ranges of the West on dry, rocky, exposed sites from the foothills to the tree line, and these stands may define both the lower and upper limits of the trees. In California, populations occur on dry, rocky, exposed sites at or near the timberline as disjunct, relict subalpine stands. P. flexilis occurs alone or intermixes with other conifer species in the tree canopy. Shade-tolerant trees can replace P. flexilis on productive sites; it persists on non-productive sites (Griffin and Critchfield 1972, Thorne et al. 2007). Outside California, P. flexilis mixes with Populus tremuloides to form a broad mosaic throughout much of the West; P. flexilis also mixes with P. aristata and other high-elevation conifers in the southern Rocky Mountains.
Pinus flexilis grows in many mountain ranges of the West on dry, rocky, exposed sites from the foothills to the tree line, and these stands may define both the lower and upper limits of the trees. In California, populations occur on dry, rocky, exposed sites at or near the timberline as disjunct, relict subalpine stands. P. flexilis occurs alone or intermixes with other conifer species in the tree canopy. Shade-tolerant trees can replace P. flexilis on productive sites; it persists on non-productive sites (Griffin and Critchfield 1972, Thorne et al. 2007). Outside California, P. flexilis mixes with Populus tremuloides to form a broad mosaic throughout much of the West; P. flexilis also mixes with P. aristata and other high-elevation conifers in the southern Rocky Mountains.
Life History Traits of the Principal Species
| Pinus flexilis | |
|---|---|
| Life forms | Tree; evergreen |
| Seed storage | Soil |
| Seed longevity | Medium |
| Mode of dispersal | Animal |
| Germination agents | Stratification—winter |
| Mode of sprouting | None |
| Survivability after fire/disturbance | Fire-sensitive; thin epidermis; no/low sprouter |
| Disturbance-stimulated flowering | No |
| Reproductive range | 20-1000 years |
| Recruitment | Episodic; low |
| Regional variation | Low |
Fire Characteristics
Most fires ignited by lightning do not spread beyond one or a few trees because stands in California have few plants in the shrub or herbaceous layers (Brooks and Minnich 2006). However, these trees have thin bark, and even moderate fire kills large trees with thicker bark. Intermediate fire frequency permits coexistence between Pinus flexilis and other trees on productive sites, and P. flexilis is common in locations with long fire intervals of low-intensity fire (Johnson 2001).
| Fire return interval | Long (200+ years) |
| Seasonality | Late summer (short) |
| Size/extent | Small |
| Complexity | Low to moderate |
| Intensity | Multiple |
| Severity | High |
| Type | Multiple |
| Regional knowledge | Great Basin ranges, Sierra Nevada |
Regional Status
- Mono (341Dd, Dj, Dl). Mixed stands occur at high elevations in the Glass, Sweetwater, and White mountains, where Pinus flexilis grows with Abies concolor and/or P. longaeva (Thorne 1982, Thorne et al. 2007). Pure stands also occur in the Sentinel Meadow and White Mountain RNAs (DeDecker 1975, see Cheng 2004).
- Sierra Nevada (M261Eo, Er, Eu). Mixed stands occur on ridges and peaks in the southern subsections, where P. flexilis grows with P. albicaulis, P. balfouriana, and/or P. contorta ssp. murrayana, for example in the Last Chance Meadow RNA (Ball 1976, see Cheng 2004). To the east of Yosemite National Park, small stands exist on the Wheeler Crest (Keeler-Wolf et al. 2003b) adjacent to shrub stands of Cercocarpus ledifolius, Artemisia arbuscula, and A. tridentata ssp. vaseyana alliances.
- Southeastern Great Basin (341Fb, Fd, Ff). Mixed stands occur in the Inyo Mountains, including Whippoorwill Flat RNA (Keeler-Wolf and Keeler-Wolf 1976, see Cheng 2004) and Panamint Range (Evens et al. 2014, Thomas et al. 2004), where they grow with P. longaeva. Small stands are also likely in the Grapevine Mountains.
- Southern California Mountains and Valleys (M262Bb, Be, Bh, Bm). Mixed stands occur on higher ridges and peaks of the Transverse Ranges, including Mount Pinos, and the San Jacinto Mountains, where P. flexilis grows with Abies concolor, P. contorta ssp. murrayana, and P. jeffreyi. Stands in the San Jacinto Mountains have Chrysolepis sempervirens understories, and they are adjacent to Pinus contorta ssp. murrayana stands (Klein and Evens 2005).
Management Considerations
Most stands in California are small and limited to a narrow band of elevation at or near the timberline. Several stands in the Sierra Nevada appear to be suffering from drought effects, insects, and fungal disease. Blister rust or a related fungus recently killed trees along the eastern slope of the Sierra Crest between Tioga Pass and Lundy Canyon (Keeler-Wolf et al. 2003b).
Associations
- Pinus flexilis / Artemisia tridentata [4], [5]
- Pinus flexilis / Cercocarpus ledifolius [3]
- Pinus flexilis - Pinus contorta / Chrysolepis sempervirens [2]
- Pinus flexilis - Pinus contorta ssp. murrayana [1], [5]
References
- [1] Ball, J.T. 1976
- [2] Klein, A.;Evens, J. 2006
- [3] Taylor, D.W. 1979
- [4] Evens, J.M.;Sikes, K.;Hastings, D.;Ratchford,J.S. 2014
- [5] CNPS Vegetation Program, 2019
- Barney, C.W. 1980
- Griffin, J.R.;Critchfield, W.B. 1972
- Hanes, T.L. 1976
- Johnson, K.A. 2001
- Paysen, T.E.;Derby, J.A.;Black, H.;Bleich, V.C.;Mincks, J.W. 1980
- Sawyer, J.O.;Keeler-Wolf, T. 1995
- Steele, R. 1990
- Thomas, K.;Franklin, J.;Keeler-Wolf, T.;Stine, P. 2004
- Thorne, R.F. 1977
- Thorne, R.F.;Schoenherr, A.;Clements, C.D.;Young., J.A. 2007
- Tomback, D.F.;Kramer, K.A. 1980
- Tomback, D.F.;Linhart, Y.B. 1990
- van Wagtendonk, J.W.;Benedict, J.M.;Sydoriak, W.M. 1998
- Vasek, F.C.;Thorne, R.F. 1977
- Vogl, R.J. 1976