Populus tremuloides Forest & Woodland Alliance
Aspen groves
Aspen groves
USDA Ecological Section Map
Summary Information
- Primary Life FormTree
- Elevation1500-3000 m
- State RarityS3.2
- Global RarityG5
- DistributionCAN: AB, BC, MB, NB, ON, QC, SK. USA: AZ, CA, CO, IA, ID, MA, ME, MI, MN, MT, ND, NH, NJ, NM, NV, NY, OR, SD, TX, UT, VT, WA, WI, WV, WY (NatureServe)
- Endemic to CaliforniaNo
- Endemic to California Floristic Province and DesertsNo
- Date Added1995/11/01
Characteristic Species
Populus tremuloides is dominant or co-dominant in the tree canopy with Abies concolor, Abies magnifica, Juniperus grandis, Juniperus occidentalis, Pinus contorta ssp. murrayana, Pinus jeffreyi and Populus trichocarpa.
Vegetation Layers
Trees < 35 m; canopy is open to continuous. Shrub layer is open to continuous. Herbaceous layer is sparse or abundant.
Membership Rules
- Populus tremuloides > 50% relative cover in the tree canopy; in mixed stands with conifers > 1% absolute cover (Keeler-Wolf et al. 2003b).
- Populus tremuloides is >30% relative cover in the tree layer and stands may be short, resprouting, shrubby “trees”. Populus trichocarpa may occur as a sub-dominant (Boul et al. 2021b).
Habitats
Depressions, swales, slopes, meadow margins, stream corridors, elevated stream terraces, and colluvial toe slopes. Soils are typically deep and well developed, often rocky. The USFWS Wetland Inventory (1996 national list) recognizes Populus tremuloides as a FAC+ plant.
Other Habitat, Alliance and Community Groupings
| MCV (1995) | Aspen series |
| NVCS (2009) | Abies concolor-Populus tremuloides forest alliance, Populus tremuloides forest alliance, Populus tremuloides seasonally flooded forest alliance, Populus tremuloides temporarily flooded forest alliance, Populus tremuloides woodland alliance |
| Calveg | Aspen (shrub), Quaking aspen, Willow-Aspen |
| Holland | Aspen riparian forest, Aspen forest |
| Munz | Not treated |
| WHR | Aspen |
| CDFW CA Code | 61.111.00 |
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 | Rocky Mountain mesic subalpine forest and woodland |
Remarks
Populus tremuloides is a fast-growing, deciduous tree that attains 20 m in height. Plants develop lateral rhi-zomes that create a set of sprouts with age. The developing stems create a clone of many trees that may cover a large area. Clones differ in phenology, leaf size and shape, branching habit, bark character, and nucleic acid composition. A clone in Utah occupies 43 ha, has more than 47,000 stems, and may be 10,000 years old (Mitton and Grant 1996). Fires, diseases, insects, browsing mammals (especially cattle and elk), and snow damage can kill stems (Howard 1996).
Trees produce seeds that are viable for less than a month. Optimum conditions for germination and seedling survival include a moist mineral seedbed and moderate temperature. Drying soil or standing water greatly reduces seedling success by the second year. Both seedlings and sprouts are shade intolerant; the tree canopy closes rapidly in young stands if not browsed. In older stands, the tree canopy is more open (Howard 1996).
Most stands occur in upland montane sites that are wet in early spring and dry by the end of the growing season. However, they occasionally occur in riparian sites that are along streams and stream terraces. Stands are transitional or self-perpetuating depending on site conditions and other trees present, especially conifers (Perala 1990). Natural disturbance, including fire, fluvial processes, beaver cutting, or avalanches, in transitional stands can maintain the dominance of P. tremuloides. Self-perpetuating stands occur on sites lacking conifers because of environmental conditions or lack of seed sources. Change in composition in such sites may take longer than 1,000 years (Mueggler 1988).
Trees produce seeds that are viable for less than a month. Optimum conditions for germination and seedling survival include a moist mineral seedbed and moderate temperature. Drying soil or standing water greatly reduces seedling success by the second year. Both seedlings and sprouts are shade intolerant; the tree canopy closes rapidly in young stands if not browsed. In older stands, the tree canopy is more open (Howard 1996).
Most stands occur in upland montane sites that are wet in early spring and dry by the end of the growing season. However, they occasionally occur in riparian sites that are along streams and stream terraces. Stands are transitional or self-perpetuating depending on site conditions and other trees present, especially conifers (Perala 1990). Natural disturbance, including fire, fluvial processes, beaver cutting, or avalanches, in transitional stands can maintain the dominance of P. tremuloides. Self-perpetuating stands occur on sites lacking conifers because of environmental conditions or lack of seed sources. Change in composition in such sites may take longer than 1,000 years (Mueggler 1988).
Life History Traits of the Principal Species
| Populus tremuloides | |
|---|---|
| Life forms | Tree; winter deciduous |
| Seed storage | Transient |
| Seed longevity | Short |
| Mode of dispersal | Wind |
| Germination agents | None |
| Mode of sprouting | Underground structures |
| Survivability after fire/disturbance | Fire-hardy; high sprouter |
| Disturbance-stimulated flowering | Yes |
| Reproductive range | 10-150+ years |
| Recruitment | Low |
| Regional variation | Low |
Fire Characteristics
Populus tremuloides is adapted to fire. New sprouts develop from adventitious roots when fire kills the old stems. Individual stems may live up to 150 years. Seedlings also readily colonize after fire, clear cutting, or other disturbances. Reduction of surface fire in P. tremuloides understories and adjacent conifer stands has increased conifer invasion in stands in California.
| Fire return interval | Medium (10-100 years) |
| Seasonality | Summer-early fall |
| Size/extent | Small to medium (dependant on topography and adjacent alliances) |
| Complexity | Moderate to high |
| Intensity | Low to moderate |
| Severity | Low to high |
| Type | Surface fire |
| Regional knowledge | Cascades, Modoc Plateau, Sierra Nevada |
Regional Status
- Klamath Mountains (M261Ad-h, Aj-l, Ap-q, At-u). The westernmost stands in California are small at montane and subalpine elevations in the eastern Marble Mountains and Trinity Alps, and on the south-facing slopes of North Yolla Bolly Mountain (Keeler-Wolf and Keeler-Wolf 1974, Sawyer 2006).
- Modoc Plateau (M261Ga-p). Stands occur along stream banks, stream terraces, and toe slopes in the Warner Mountains (Riegel et al. 1990, S. Smith 1998b), where they intermix with larger stands of Abies concolor, Pinus jeffreyi, and P. ponderosa var. washoensis, and with shrubland alliances. Small stands are common in basalt outcrops and cliff bases surrounded by Juniperus occidentalis woodlands. Stands in isolated pockets in the Clear Lake Hills occur in Artemisia tridentata shrublands and Poa secunda grassland.
- Mono (341Da-f, Dh, Dj-l). Stands in the White Mountain RNA (Taylor 1979, see Cheng 2004) are along creeks; those in lower canyons of McGee Creek and other drainages of the Sierra Nevada are scrubby thickets over talus. Stands in the Sweetwater Mountains are along creeks and adjacent to meadows.
- Northwestern Basin and Range (342Bb, Bd-e). Stands scattered in the Cottonwood and Skedaddle mountains on north-facing slopes mix with stands of the Juniperus occidentalis and shrubland alliances.
- Sierra Nevada (M261Ea-d, Eh-r, Et-u). Stands of this type occur in the Sierra Nevada at Babbitt Peak, Bell Meadow, Critchfield, and Moses Mountain RNAs (Cheng 2004), Yosemite National Park (Keeler-Wolf et al. 2003b), and Sequoia Kings Canyon National Park (NPS-SEKI 2009). Stands occur generally throughout (Potter 2005) and on the east side of the Sierra Nevada (Manning and Padgett 1995).
- Southern California Mountains and Valleys (M262Bh). Two small stands occur in the San Bernardino Mountains; the largest is along Arrastre Creek.
- Southern Cascades (M261Da, Dc-f, Dh-j, Dm). Localized stands occur on rock outcrops, stream terraces, and large, vernally wet depressions locally called reservoirs (Smith 1998b).
Management Considerations
Populus tremuloides is a sensitive resource in the Sierra Nevada and other mountains of California (Shepperd et al. 2006). Fire exclusion from P. tremuloides understories and from adjacent conifer stands has increased conifer invasion. Cattle browsing has removed sprouting suckers, compacted soil, changed species composition to unpalatable Rosa woodsii, and caused increase in the cover of non-native species. Stands may die out if browsing and grazing pressure are heavy (Manning and Padgett 1995). When released from this pressure, suckers return. Stream down cutting has lowered water tables and reduced the vigor of many stands.
Associations
Riparian Stands with a Simple Tree Canopy
- Populus tremuloides [7]
- Populus tremuloides / mesic forb [6]
- Populus tremuloides / Prunus [6]
- Populus tremuloides / Rosa woodsii [1], [11]
- Populus tremuloides / Symphoricarpos albus [6]
- Populus tremuloides / Symphyotrichum foliaceum [5]
- Populus tremuloides / Veratrum californicum [1], [3], [4], [5], [6], [11]
Stands with a Mixed Tree Canopy
- Populus tremuloides - Pinus contorta / Artemisia tridentata / Poa pratensis [1], [10]
- Populus tremuloides / Pinus jeffreyi [1]
Upland Stands with a Simple Tree Canopy
- Populus tremuloides / Artemisia tridentata [1], [8]
- Populus tremuloides / Artemisia tridentata / Monardella odoratissima - Kelloggia galioides [1]
- Populus tremuloides / Bromus carinatus [2]
- Populus tremuloides / dry graminoid [6]
- Populus tremuloides / Monardella odoratissima [1]
- Populus tremuloides / Poa pratensis [1], [6]
- Populus tremuloides / Symphoricarpos rotundifolius [3], [6], [9], [11]
- Populus tremuloides / Symphyotrichum foliaceum [5]
References
- [1] Keeler-Wolf, T.;Schindel, M.;San, S.;Moore, P.;Hickson, D. 2003b
- [2] Manning, M.E.;Padgett, W.G. 1995
- [3] Potter, D.A. 1994
- [4] Potter, D.A. 2005
- [5] Riegel, G.M.;Thornburgh, D.A.;Sawyer, J.O. 1990
- [6] Smith, S. 1998b
- [7] Talley, S.N. 1977
- [8] NPS-SEKI, 2009
- [9] Boul, R.;Keeler-Wolf, T.;Ratchford, J.;Haynes, T.;Hickson, D.;Yacoub, R.;Harbert, B.;Evens, J. 2021b
- [10] CNPS Vegetation Program, 2019
- [11] Ratchford, J.;Boul, R.;Keeler-Wolf ,T.;Evens, J. 2024b (in progress)
- Barbour, M.G. 1988
- Barry, W.J. 1971
- Barry, W.J. 1989a
- Barry, W.J. 1989b
- Cheatham, N.H.;Haller, J.R. 1975
- DeByle, N.V.;Zasada, J.C. 1980
- Griffin, J.R.;Critchfield, W.B. 1972
- Howard, J.L. 1996
- Keeler-Wolf, V.;Keeler-Wolf, T. 1974
- Minnich, R.A. 1976
- Mueggler, W.F. 1994
- Paysen, T.E.;Derby, J.A.;Black, H.;Bleich, V.C.;Mincks, J.W. 1980
- Paysen, T.E.;Derby, J.A.;Conrad, C.E. 1982
- Perala, D.A. 1990
- Sawyer, J.O. 2006
- Shiflet, T.N. 1994
- Smith, C.F. 1998a
- Thorne, R.F. 1976
- Thorne, R.F. 1977
- van Wagtendonk, J.W.;Fites-Kauffman, J. 2006