Madrone Ecology

The lone madrone is a beautiful sight, but more often than not one finds them in a community mixed with other trees, shrubs and herbaceous plants. These plant "alliances", "associations" and "groups" replicate themselves across the landscape depending on aspect towards the predominant sun direction, topography, elevation, underlying soils, proximity to saltwater, and human tending of the ecosystem to name a few. Unfortunately, some of these associations are increasingly uncommon, ranked by NatureServe as vulnerable or imperiled - noted below. These forest communities are named by dominant, co-dominant or characteristically present plant species often labeled in tiers. The dashes (-) in the names separate species in the same canopy layer; slashes (/) separate species in different canopy layers.

Madrone communities in the species range

Salish Sea/Georgia Straight in British Columbia & Puget Trough in Washington

Arbutus / hairy manzanita - vulnerable

Garry oak - arbutus

Pacific Madrone - Lodgepole Pine / Salal Forest

Southern Vancouverian Dry Douglas-fir - Madrone Woodland

Douglas-fir-Pacific madrone Woodland

Douglas-fir - Pacific Madrone / Oceanspray Forest - critically imperiled

Pacific Madrone - (Douglas-fir) / Salal Forest

North Pacific Maritime Dry-Mesic Douglas-fir-Western Hemlock Forest

Douglas-fir - Grand Fir - Pacific Madrone Forest & Woodland

Willamatte Valley-Klamath-Siskiyou

Cascadian Oregon White Oak - Conifer Forest & Woodland

  • Oregon White Oak - Ponderosa Pine - Douglas-fir Forest & Woodland Group

Tanoak - Pacific Madrone Forest Alliance

Pacific Madrone - Douglas-fir - Oak species / Pacific Poison-oak Woodland - vulnerable

Southern Cascades-OR/CA Coast Range

Californian Moist Coastal Mixed Evergreen Forest

  • Douglas-fir - Tanoak - Pacific Madrone Forest Group

Bishop Pine - Pacific Madrone / California Huckleberry Forest - imperiled

Pacific Madrone Alliance Mixed evergreen forest, Tanoak; Northern mixed evergreen forest; Montane hardwood forest

Sierra Nevada

Pacific Madrone Woodland/Forest Alliance with tanoak, canyon live oak, interior live oak, California black oak, and bay laurel

Douglas fir-Pacific madrone @Salish Sea

Oregon white oak-Pacific madrone @Willamette Valley/Klamath-Siskiyou

redwood- Pacific madrone @Coast Range of California

The larger environment and landscape history influences the type of plant community one finds.

Environment: Common in close proximity to salt water on Western edge of North America. Isolated patches inland in mountains. In Southern range found in ravines. Generally doesn't tolerate extremes of heat or cold.

Topography and Aspect: Can be found on gentle to steep slopes, "sunny slopes" and ridge crests of bedrock hills. Hillsides and rocky knolls with dry, generally southern exposures. In Southern range found on north facing slopes.

Soils: Sites can be shedding and dry, colluvial veneers/residuum over bedrock. Soils are described as shallow, rubbly, very fine (sometimes glacial) sands to medium textured-gravelly (glacial outwash and till) soils and well drained. Due to these conditions, soil moisture regime is very xeric to subxeric. Often described as "nutrient-poor ."

Shade tolerance: Moderate

Vegetation: Rarely dominant, generally co-dominant, "subordinate" or diagnostic of unique plant communities that are relatively drought tolerant. Herb layer may poorly develop.

Disturbance/Succession: In the pre-colonial landscape, a moderate-severity fire regime likely prevailed across the species range with variable severity and intermediate frequency. Coastal development has resulted in widespread loss, fragementation and alteration of madrone ecosystems. Wildfire may benefit madrones by clearing pathogens and removing encroaching vegetation, such as Douglas-fir. See more on Better Management Practices.

Biodiversity notes: Berries provide forage for birds in the fall and into winter. Tendency for heart rot is favorable for cavity nesting birds and other animals. Can be browsed heavily by deer.

The wide-spreading root system is associated with ericoid mycorrhiza. The fungus is characterized by “coils” that form in the epidermal cells of the fine hair roots of ericaceous species. The fungi colonize the root cells and establish hyphal networks around the roots, providing increased water and nutrient absorption while the plant in turn provides the fungus with carbohydrates through photosynthesis.

Ericoid mycorrhizal fungi also have hydrolytic and oxidative enzymes that are important in mobilizing nutrients from organic matter and leaf litter. This is a big reason for madrone’s ability to persist through drought and thrive in relatively harsh conditions such as rocky bluffs or soils we may characterize as "nutrient deficient."

There has also been investigation into the symbiotic associations between the madrone soil community and links to nearby Douglas-fir that may assist with disease resistance in madrone.

Madrone superpower: lignotuber. Where the base of the stem meets the ground is a woody swelling of the root crown. A more vague term is "burl." It can be more pronounced in some trees more than others. This portion of the tree contains dromant buds and stores carbohydrates and nutrients necessary for bud development that supports growth and where new stems can sprout vegetatively. This reproductive strategy has commonly evolved in perennial shrubs of Mediterranean-type ecosystems. Thousands of meristematic foci may be present. Similar to stem cells, undifferentiated cells and tissue are capable of growing and changing into new shoots in response to fire or other damage. This is what allows the trees to "resprout" or replace stems that have been lost.

Madrone flowers are fragrant and show up as large drooping clusters referred to as panicles of small, white, urn-shaped flowers. "Urn"= resembles an upside down rounded vase. The species has both male and female organs; the plant is self-fertile.

Flowering period: starts in April and ends by June across the species range

calyx is 5-parted surrounding the urn-shaped, united petals | petals are 6-7 mm long | ovary superior | 10 stamens with pilose filaments near the base | anthers are awned from the back to near the tip, and open by terminal slitlike pores

Bees are the principle pollinator though flies and ants are attracted to the nectar. If you are lucky you might see a hummingbird visiting the flowers.

Geek out! Resources to explore and find more detail about plant communities:Association for Biodiversity Information, California Department of Fish and Wildlife and California Native Plant Society. (2003).Classification of the Vegetation of Point Reyes National Seashore Golden Gate National Recreation Area, Samuel P. Taylor, Mount Tamalpais, and Tomales State Parks, Marin, San Francisco, and San Mateo Counties, California.
B.C. Conservation Data Centre. (2020). BC Species & Ecosystems Explorer: Arbutus menziesii. B.C. MoE BC Conservation Framework. 2009. BC Ministry of Environment.
Chappell, C.B. (2004). Upland Plant Associations of the Puget Trough Ecoregion, Washington. Washington Natural Heritage Program, Department of Natural Resources.
Kentner, E., J. Klein and J. Evens. (2006). Classification of vegetation associations from the Mount Tamalpais watershed, Nicasio Reservoir, and Soulajule Reservoir
Klein, A., Keeler-Wolf, T. and J. Evens. (2015). Classification of the Vegetation Alliances and Associations of Sonoma County, California Volume 2 of 2 – Vegetation Descriptions.
Klein, A., J. Crawford, J. Evens, Keeler-Wolf, T. and D. Hickson. (2007). Classification of the Vegetation Alliances and Associations of the Northern Sierra Nevada Foothills, California Vol. 2.
NatureServe. {2020). NatureServe Explorer. NatureServe, Arlington, Virginia. Available
Rocchio J.F. and Crawford R.C. (2015). Ecological Systems of Washington State. A Guide to Identification. Natural Heritage Report 2015 -04. Washington State Department of Natural Resources.
Sawyer, J.O., T. Keeler-Wolf, and J.M. Evens. 2009. A Manual of California Vegetation, Second Edition. California Native Plant Society, Sacramento. 1300 pp
University of British Columbia Department of Forest Sciences. (1991). Vegetation and Site Classification for Coastal British Columbia. Vegetation and Environment Summaries. University. B.C. Vancouver, BC. B.C. Ministry. For. Red. Branch Victoria.
USNVC [United States National Vegetation Classification]. 2020. United States National Vegetation Classification Database, V2.03. Federal Geographic Data Committee, Vegetation Subcommittee, Washington DC. Available