Measuring the health of Mt. Tam

Maintaining a healthy, vibrant and diverse Mt. Tam begins with understanding how key ecological resources are faring, and how we can better care for this iconic and beloved place.

One Tam partners and Bay Area scientists have come together to try to answer the question: How healthy are Mt. Tam's natural resources?

Open-canopy Oak Woodland Communities

Open-canopy Oak Woodland Communities

MMWD Photo


Open-canopy oak woodlands are in Fair condition, with a Declining trend, mostly due to invasive species, Sudden Oak Death, and Douglas-fir (Pseudotsuga menziesii) encroachment.

Open-canopy oak woodland condition and trend in the One Tam area of focus

Douglas-fir & Invasive Species

There is some recruitment of Douglas-fir into these woodlands where they are close to existing mature Douglas-fir or mixed Douglas-fir/coast redwood/tanoak forests. Several species of broom continue to rapidly invade and colonize within many of Mt. Tam’s oak woodlands.

Sudden Oak Death

Sudden Oak Death continues to be the major stressor in this community, and estimates show that up to 30 percent or more of coast live oak adults and 20 percent or more of black oak adults have been lost (McPherson et al., 2010; Swiecki and Bernhardt, 2013). This disease is expected to continue to kill oaks and may eventually transform these oak woodlands into woodlands or forests with a very minor oak component.


Oak woodlands are known to be centers of high avian diversity (California Partners In Flight, 2002) and our current assessment of birds in this community type finds that the full complement of expected birds are present.

Learn More


California Partners in Flight. (2002). The oak woodland bird conservation plan: A strategy for protecting and managing oak woodland habitats and associated birds in California, Version 2.0. Stinson Beach, CA: Point Reyes Bird Observatory (now Point Blue). Available at:

McPherson, B. A., Mori, S. R., Wood, D. L., Kelly, M., Storer, A. J., Svihra, P., & Standiford, R. B. (2010). Responses of oaks and tanoaks to the sudden oak death pathogen after 8 years of monitoring in two coastal California forests. Forest Ecology and Management, 259 (12), 2248-2255. Available at:

Swiecki, T. J. & Bernhardt, E. A. (2013). Long-term trends in coast live oak and tanoak stands affected by Phytophthora ramorum canker (sudden oak death): 2000-2010 disease progress update. Retrieved from