Print Report
A3673 Pinus ponderosa - Calocedrus decurrens - Pseudotsuga menziesii Forest Alliance
Type Concept Sentence: This forest alliance is codominated by Pseudotsuga menziesii, Pinus ponderosa, and Calocedrus decurrens. A variety of other conifers usually co-occur, including Pinus lambertiana, Pinus jeffreyi, and/or Pinus attenuata. This alliance occurs along the western slope of the southern Oregon Cascades and throughout the Klamath Mountains in Oregon and California, south into the California Coast Ranges. It occurs at low to middle elevations (600-1200 m) with high winter rainfall (75-250 cm), warm to hot, dry summers, and extremely variable geology.
Common (Translated Scientific) Name: Ponderosa Pine - Incense-cedar - Douglas-fir Forest Alliance
Colloquial Name: Ponderosa Pine - Incense-cedar - Douglas-fir Forest
Hierarchy Level: Alliance
Type Concept: These forests are typically codominated by Pseudotsuga menziesii, Pinus ponderosa var. benthamiana, and Calocedrus decurrens. A variety of other conifers co-occur, including Pinus lambertiana, Pinus jeffreyi, and/or Pinus attenuata. A diverse broad-leaved deciduous or evergreen tree layer may be present and may include Quercus garryana, Arbutus menziesii, Notholithocarpus densiflorus, Umbellularia californica, Acer macrophyllum, and others. Quercus kelloggii and Quercus chrysolepis may also codominant in the Sierra Nevada. A shrub layer may or may not be present and is generally best developed in comparatively moist northern or high-elevation stands. Common species in such mesic stands include Acer circinatum, Mahonia nervosa, Gaultheria shallon, and Cornus nuttallii, which can occasionally be a small tree. In southern or lower elevation stands, drought-tolerant species such as Holodiscus discolor, Toxicodendron diversilobum, Symphoricarpos mollis, Ceanothus spp., and Arctostaphylos spp. become prevalent. The herbaceous understory can be similarly variable, depending upon site moisture, canopy closure, and location. This alliance occurs along the western slope of the southern Oregon Cascades and throughout the Klamath Mountains in Oregon and California. From the Klamath region, the range extends south into the California Coast Ranges as far as the Yolla-Bolly region, and in the Sierra Nevada as far south as Yosemite National Park. These communities are usually associated with sunny aspects and droughty or infertile soils of lower mountain slopes. They occur at low to middle elevations (600-1200 m) with high winter rainfall (75-250 cm), warm to hot, dry summers, and extremely variable geology.
Diagnostic Characteristics: Upper canopy mixed dominance by two of the three nominal species.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This alliance includes Pinus ponderosa var. benthamiana; other races of Pinus ponderosa are in other USNVC groups. This alliance lacks Abies concolor in the upper canopy or, if present, has less than 10% relative cover, or may be present only in subcanopy regenerating layers.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation within this alliance is typified by a closed or nearly closed canopy of needle-leaved evergreen trees approaching 50 m in height. A subcanopy of broad-leaved cold-deciduous or evergreen trees is common. The shrub layer is often structurally diverse, sometimes with several strata of cold-deciduous and evergreen species. The herbaceous layer is variable, from sparse graminoid cover in xeric stands to dense forb, graminoid, and fern cover in moist habitats.
Floristics: These forests are typically codominated by Pseudotsuga menziesii, Pinus ponderosa var. benthamiana (= var. pacifica), and Calocedrus decurrens. A variety of other conifers co-occur, including Pinus lambertiana, Pinus jeffreyi, and Pinus attenuata. A diverse broad-leaved deciduous or evergreen tree layer may be present and may include Quercus garryana, Arbutus menziesii, Notholithocarpus densiflorus (= Lithocarpus densiflorus), Umbellularia californica, Acer macrophyllum, and others. Quercus kelloggii and Quercus chrysolepis are reported to share a codominance with these mixed conifers in Yosemite and other areas in the Sierra Nevada. A shrub layer may or may not be present and is generally best developed in comparatively moist northern or high-elevation stands. Common species in such mesic stands include Acer circinatum, Mahonia nervosa, Gaultheria shallon, and Cornus nuttallii, which can occasionally be a small tree. In southern or lower elevation stands, drought-tolerant species such as Holodiscus discolor, Toxicodendron diversilobum, Symphoricarpos mollis, Ceanothus spp., and Arctostaphylos spp. become prevalent. The herbaceous understory can be similarly variable, depending upon site moisture, canopy closure, and location.
Dynamics: These communities are usually associated with seasonal drought and historically high fire frequencies when high frequency of late summer lightning storms, at a time of low fuel moisture, created short fire-return intervals (20-30 years). With fire suppression stands have become more closed and unnaturally dense. Many of these communities are believed to be seral to Abies concolor forests in the absence of fire or other disturbance.
Environmental Description: The associations in this alliance occur in low to middle elevations (600-1200 m) with high winter rainfall (75-250 cm), warm to hot, dry summers, and extremely variable geology. These communities are usually associated with sunny aspects and droughty or infertile soils of lower mountain slopes.
Geographic Range: This alliance is found along the western slope of the southern Oregon Cascades, throughout the Klamath Mountains, south into the California Coast Ranges as far as the Yolla-Bolly region, and in the Sierra Nevada as far south as Yosemite National Park.
Nations: MX?,US
States/Provinces: CA, MXBCN?, OR
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899725
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: A.155, A.2559
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Pinus ponderosa - Calocedrus decurrens (Mixed conifer forest) Alliance (Sawyer et al. 2009) [87.015.00]
= Pinus ponderosa - Calocedrus decurrens Forest Alliance (Keeler-Wolf et al. 2012)
= Pinus ponderosa - Calocedrus decurrens Forest Alliance (Keeler-Wolf et al. 2012)
- Atzet, T. A., D. E. White, L. A. McCrimmon, P. A. Martinez, P. R. Fong, and V. D. Randall. 1996. Field guide to the forested plant associations of southwestern Oregon. Technical Paper R6-NR-ECOL-TP-17-96. USDA Forest Service, Pacific Northwest Region, Portland, OR.
- Atzet, T., and D. L. Wheeler. 1984. Preliminary plant associations of the Siskiyou Mountains Province, Siskiyou National Forest. USDA Forest Service, Pacific Northwest Region, Portland, OR.
- Atzet, T., and L. A. McCrimmon. 1990. Preliminary plant associations of the southern Oregon Cascade Mountain Province. USDA Forest Service, Pacific Northwest Region, Siskiyou National Forest, Grants Pass, OR. 330 pp.
- Chappell, C., R. Crawford, J. Kagan, and P. J. Doran. 1997. A vegetation, land use, and habitat classification system for the terrestrial and aquatic ecosystems of Oregon and Washington. Unpublished report prepared for Wildlife habitat and species associations within Oregon and Washington landscapes: Building a common understanding for management. Prepared by Washington and Oregon Natural Heritage Programs, Olympia, WA, and Portland, OR. 177 pp.
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Franklin, J. F., and C. T. Dyrness. 1973. Natural vegetation of Oregon and Washington. General Technical Report PNW-8. USDA Forest Service, Pacific Northwest Forest and Range Experiment Station, Portland, OR. 417 pp.
- Keeler-Wolf, T., P. E. Moore, E. T. Reyes, J. M. Menke, D. N. Johnson, and D. L. Karavidas. 2012. Yosemite National Park vegetation classification and mapping project report. Natural Resource Technical Report NPS/YOSE/NRTR--2012/598. National Park Service, Fort Collins, CO.
- ORNHP [Oregon Natural Heritage Program]. No date. Unpublished data files. Oregon Natural Heritage Program, The Nature Conservancy, Portland, OR.
- Sawyer, J. O., T. Keeler-Wolf, and J. Evens. 2009. A manual of California vegetation. Second edition. California Native Plant Society, Sacramento CA. 1300 pp.
- Sawyer, J. O., and T. Keeler-Wolf. 1995. A manual of California vegetation. California Native Plant Society, Sacramento. 471 pp.