Alnus rubra Forest Alliance
Red alder forest
Red alder forest
USDA Ecological Section Map
Summary Information
- Primary Life FormTree
- Elevation0-750 m
- State RarityS4
- Global RarityG5
- DistributionCAN: BC. USA: AK, CA, ID, OR, WA (NatureServe)
- Endemic to CaliforniaNo
- Endemic to California Floristic Province and DesertsNo
- Date Added1995/11/01
Characteristic Species
Alnus rubra is dominant or co-dominant in the tree canopy with Abies grandis, Garrya elliptica, Picea sitchensis, Populus trichocarpa, Pseudotsuga menziesii, Salix hookeriana, Salix lasiolepis, Salix sitchensis, Sequoia sempervirens, Tsuga heterophylla and Umbellularia californica.
Vegetation Layers
Trees < 40 m; canopy is continuous. Shrub layer is sparse to intermittent. Herbaceous layer is open to continuous, especially with ferns and forbs.
Membership Rules
- Alnus rubra > 50% relative cover in tree layer (Keeler-Wolf et al. 2003a, Evens and Kentner 2006).
Habitats
Stream and river backwaters, banks, bottoms, flood plains, mouths, terraces, and slopes of all aspects. The USFWS Wetland Inventory (1996 national list) recognizes Alnus rubra as a FACW plant.
Other Habitat, Alliance and Community Groupings
| MCV (1995) | Red alder series |
| NVCS (2009) | Alnus rubra forest alliance, Alnus rubra seasonally flooded forest alliance, Alnus rubra temporarily flooded forest alliance |
| Calveg | Red alder |
| Holland | Red alder riparian forest, North Coast riparian scrub, Woodwardia thicket, Red alder forest |
| Munz | North Coast coniferous forest |
| WHR | Montane hardwood-conifer |
| CDFW CA Code | 61.410.00 |
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 | Californian-Vancouverian Montane and Foothill Forest |
| Group | Upland Vancouverian mixed woodland and forest |
Remarks
Alnus rubra is a deciduous hardwood that attains a height of 40 m and an age of 100 years. Tree root systems are shallow. Plants begin producing seeds at 10 years, with large crops usually every 4 years. Seeds shed in the autumn are dispersed by wind and water. Seedlings establish on many well-lighted substrates, and they do best on mineral soil. Plants are associated with nitrogen-fixing bacteria, and they are shade intolerant. Young plants vigorously sprout (Favorite and Immel 2003, Franklin et al. 1981, Harrington 1990, Uchytil 1989b).
The alliance occurs primarily near the coast in California as both riparian and upland stands. Stands typically include a well-developed shrub understory of species such as Rubus spectabilis, R. ursinus, and Sambucus racemosa (Cheng 2004, Keeler-Wolf et al. 2003a, Evens and Kentner 2006). Stands were much more restricted in the past, occurring chiefly along streams or natural landslides; today seedlings and stands of A. rubra easily establish in upland areas that have been recently logged (Sawyer 2006).
The alliance occurs primarily near the coast in California as both riparian and upland stands. Stands typically include a well-developed shrub understory of species such as Rubus spectabilis, R. ursinus, and Sambucus racemosa (Cheng 2004, Keeler-Wolf et al. 2003a, Evens and Kentner 2006). Stands were much more restricted in the past, occurring chiefly along streams or natural landslides; today seedlings and stands of A. rubra easily establish in upland areas that have been recently logged (Sawyer 2006).
Life History Traits of the Principal Species
| Alnus rubra | |
|---|---|
| Life forms | Tree; winter deciduous |
| Seed storage | Transient |
| Seed longevity | Short |
| Mode of dispersal | Water/hydrological; wind |
| Germination agents | None |
| Mode of sprouting | Buds on large branches or trunks |
| Survivability after fire/disturbance | Fire-sensitive; thin epidermis; no/low sprouter |
| Disturbance-stimulated flowering | No |
| Reproductive range | 10-100 years |
| Recruitment | High |
| Regional variation | Low |
Fire Characteristics
Older stands tend to occur on moist sites that rarely expe-rience natural fire, but Alnus rubra rapidly colonizes soil exposed after fire if seed sources are available. Large, aboveground branches of A. rubra may also sprout if the fires are not severe.
| Fire return interval | Long |
| Seasonality | Summer-early fall |
| Size/extent | Small to medium; dependent on fire in adjacent alliances (this alliance will not readily carry fire) |
| Complexity | Moderate to high |
| Intensity | Low to moderate |
| Severity | Moderate to high |
| Type | Surface-passive crown fire |
| Regional knowledge | Central Valley, Modoc Plateau; Central Coast, Klamath, Cascade, and North Coast ranges |
Regional Status
- Central California Coast (261Ad, Af, Ah, Aj-k). Stands occur along the coastline and localized along streams as far south as San Luis Obispo Co. Most alder in the Santa Lucia Range is Alnus rhombifolia.
- Klamath Mountains (M261Aa-b, As). The western edge of the section supports streamside stands, but the dominant alder quickly changes to A. rhombifolia to the east (Sawyer 2006).
- Northern California Coast (263Aa-b, Ad-l). Stands occur along the coastline from Del Norte to Marin counties or inland along streams. Descriptions of stands include reports from Point Reyes National Seashore (Keeler- Wolf et al. 2003a), at Nicasio Reservoir on Marin Municipal Watershed lands (Evens and Kentner 2006), at Yurok RNA (Taylor 1982, see Cheng 2004), at Stagecoach Hill Azalea Preserve (Stuart et al. 1986), and elsewhere in the section (Clark 1937, Jimerson 1993, Newton 1989). North of Point Mendocino, short-lived stands establish on the uplands after logging.
Management Considerations
Mature stands along the coastline and inland along streams are sufficiently wet that conifer establishment is slow. On the uplands, Alnus rubra is a fast-growing early-seral tree, quickly establishing after logging activities end. Managers use herbicides on commercial timberlands to release the planted conifers in the resulting alder stands. This practice further impacts native plant populations that have already been reduced by logging.
Associations
- Alnus rubra / Gaultheria shallon [3]
- Alnus rubra - Pseudotsuga menziesii / Acer circinatum / Claytonia sibirica [1]
- Alnus rubra / Rubus spectabilis - Sambucus racemosa [2], [4], [5], [6], [7], [8], [9]
- Alnus rubra / Salix lasiolepis - Rubus spp. [1], [2], [5], [7], [8], [9]
References
- [1] Jimerson, T.M. 1993
- [2] Keeler-Wolf, T .;Schirokauer, D.;Meinke, J.;van derLeeden, P. 2003a
- [3] Stuart, J.D.;Matthews, S.;Nilson, A. 1986
- [4] Taylor, D.W. 1982
- [5] Klein, A.;Keeler-Wolf, T.;Evens, J. 2015
- [6] Stumpf, K.;Cogan Technology;Kier Associates, 2017
- [7] Buck-Diaz, J.;Sikes, K.;Evens, J.M. 2021a
- [8] Sikes, K.;Buck-Diaz, J.;Evens, J. 2021
- [9] Sikes, K.;Buck-Diaz, J.;Vu, S.;Evens, J. 2023
- Antos, J.A.;Allen, G.A. 1990
- Cheng, S. 2004
- DeBell, D.S.;Turpin, T.C. 1983
- Evens, J.M.;Kentner, E. 2006
- Favorite, J.;Immel, D.L. 2003
- Franklin, J.F.;Cromack, K.;Denison, W.;McKee, A.;Maser, C.;Sedell, J.;Swanson, F.;Juday, G. 1981
- Griffin, J.R.;Critchfield, W.B. 1972
- Harrington, C.A. 1990
- Holstein, G. 1984
- McBride, J.R. 1994
- Miller, R.E. 1980
- Paysen, T.E.;Derby, J.A.;Black, H.;Bleich, V.C.;Mincks, J.W. 1980
- Sawyer, J.O. 2006
- Sawyer, J.O. 2007
- Uchytil, R.J. 1989b