Santa Cruz Island, USA

Santa Cruz Island, USA

© J. Decruyenaere
Santa Cruz Island, USA

Santa Cruz Island, USA

© J. Decruyenaere

Pinaceae

Pinus torreyana subsp. insularis J.R.Haller

A very small population found on Santa Rosa Island in California, USA where potential threats include pests and diseases and fire.

Distribution

USA: S California (Santa Barbara Co.: Santa Rosa Island).

This tiny population of about 1000 mature trees covers less than 100ha in two subpopulations on a near-shore island. Records from Santa Catalina Island represent introduced trees.

Habitat and Ecology

On steep and/or open slopes and in canyons near the coast, forming small stands.

Conservation Status

Global status and rationale

Vulnerable D2

The extent of occurrence and area of occupancy are very small and well within the threshold for Critically Endangered, but there is no evidence of decline. The estimate of 1000 mature trees, probably not accurate, could be in reality below or above this figure. So what remains is the AOO of less than 100 hectares (1km²) and the risk of stochastic events, making this taxon Vulnerable under criterion D.

Global threats

This subspecies is at high risk from stochastic events such as fire, pest infestation, or disease, all of which could wipe out this subspecies easily. The trees enjoy legal protection, but that is not an effective buffer against these risks.

Conservation Actions

The entire population is now protected within a reserve.

References and further reading

  1. Farjon, A. (2013). Pinus torreyana ssp. insularis. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. <www.iucnredlist.org>. Downloaded on 13 July 2013.
  2. Griffin, J.R. & Critchfield, W.B. (1972). The distribution of forest trees in California. USDA Forest Service, Research Paper PSW-82 (reprinted with supplement, 1976). Pacific Southwest Forest and Range Experiment Station, Berkeley, CA.
  3. Haller, J.R. (1986). Taxonomy and relationships of the mainland and island populations of Pinus torreyana. Systematic Botany 11: 39-50.
  4. Hubbs, C. L., Whitaker, T. W. & Reid, F. M.H., Torrey Pines State Reserve, The Torrey Pines Association, 1991
  5. Lanner, R.M. (1999). Conifers of California. Cachuma Press, Los Olivos, California.
  6. Ledig, F.T. & Conkle, M.T. (1983). Gene diversity and genetic structure in a narrow endemic, Torrey pine. Evolution 37: 79-85.
  7. Waters, E.R. & Schaal, B.A.(1991). No variation is detected in the chloroplast genome of Pinus torreyana. Canadian Journal of Forest Research 21: 1832-1835.