Pseudotsuga macrocarpa (Vasey) Mayr

A Californian endemic that may be susceptible to increased fire frequencys and climate change.


Endemic to southern California (San Rafael Mts., San Gabriel Mts., San Bernardino Mts., San Jacinto Mts., and Santa Ana Mts.), USA

Habitat and Ecology

Pseudotsuga macrocarpa grows on the seaward slopes of coastal mountains at elevations between 275 m and 2450 m a.s.l., on mountain soils of various origin, usually rocky and well drained, dry in summer. The climate is warm temperate, with cool, moist winters and warm, dry summers (annual precipitation 500 mm to 1500 mm), snow occurs only at the higher elevations. Above 800 m (Transition Zone) this species is mainly mixed with Pinus jeffreyi, P. ponderosa, P. coulteri, and Abies concolor at the highest elevations. Common evergreen shrubs in these open pine forests are Ceanothus cordulatus and Arctostaphylos patula. At the lower elevations it occurs in the drier Canyon Live Oak forest type, with sclerophyllous oaks, e.g. Quercus kelloggii, Q. chrysolepis and Q. agrifolia.
Big-cone Douglas-fir shows considerable resistance to relatively intense fires as a result of its thick bark and ability to respout after mortality of the aboveground tree (Steel et al. 2015).

Human Uses

The wood of this species is close grained, hard and heavy, but not durable. It would only be suitable for coarse lumber, but is not exploited due to scarcity of the resource and other, more ecological values.

Conservation Status

Global Status

Near Threatened

Global Rationale

Based on comprehensive mapping of localities from herbarium data, the area of ocupancy (AOO) can be estimated as 315 km² (below the maximum of 500 km² threshold for Endangered), and the population is certainly fragmented. As yet, there is no evidence of decline, save for some reports on there being few larger trees in some localities after fires. Near Threatened is therefore the appropriate category as it almost qualifies under criterion B2ab(iii,v). An increase in the frequncy of fires, allied with extreme weather events associated with climate change remain the bigest threats in the near future.

Conservation Actions

Stands of this conifer are in need of protection from especially man-made fires, including those in protected areas.

References and further reading

  1. Burns, R.M. and Honkala, B.H. 1990. Silvics of North America. USDA, Forest Service, Washington, DC.
  2. Farjon, A. 2013. Pseudotsuga macrocarpa. The IUCN Red List of Threatened Species 2013: e.T34025A2840746. Downloaded on 07 August 2017
  3. Steel, Z.L., Safford, H.D. and Viers, J.H., 2015. The fire frequency‐severity relationship and the legacy of fire suppression in California forests. Ecosphere, 6(1), 1-23.

External links

Entry information:

Entry author:

P.Thomas ·

Entry last edited:

8 Nov 2019

Recommended Citation:

P.Thomas, 2019, Pseudotsuga macrocarpa, from the website: ‘Threatened Conifers of The World’ ( Downloaded on 22 May 2024.

Categorised in:

Near Threatened, Fire, Northern Mexico / SW USA and Pinaceae