Pinus torreyana subsp. torreyana

Pinaceae

Although afforded some protection within the Torrey State Reserve in California, USA, unprotected trees are threatened by urbanisation

Distribution

USA: S California (San Diego Co., on the coast north of San Diego).

There are an estimated 3000–3500 mature trees in the population.

Habitat and Ecology

Pinus torreyana is a relict species now confined to littoral habitat on the coast (up to 1.6km inland) and on a small island off the coast of southern California. It grows from immediately above the high tide mark to about 180m metres above sea-level on rocky or sandy slopes. On these sites it seems dependent on the daily fog that comes in from the ocean in the afternoon, mitigating the heat of the sun and the resulting excessive evapo-transpiration. It grows with a sparse chaparral and few other trees; in ravines sometimes accompanied by a few oaks (Quercus spp.) and Arbutus menziesii

Human Uses

Torrey pine is not used as a timber tree; at present the two disjunct populations are protected by law. It is in cultivation in California in gardens and some arboreta, but rare elsewhere. In the better growing conditions of gardens it can grow to a large tree; a specimen in New Zealand was 45 m tall with a girth of 1.5m in 1982 (Grimshaw & Bayton, 2009). Although its conservation seems more or less cared fore at present, growing this species more widely as an ex situ backup is to be recommended; it is also an interesting species to grow and requires a mild climate with warm, sunny summers and (near) absence of frost in winter.

Conservation Status

Global status and rationale

Critically Endangered B1ab(ii,iii,v)+2ab(ii,iii,v)

Urbanisation is encroaching on the mainland population (subsp. torreyana) with the effect that trees outside the Torrey Pines State Park are still disappearing. There is also an acute risk of a major fire wiping out a large part of the population, a risk that is known to increase for various reasons where housing developments are near the population in a potentially fire-prone area. The present decline is probably slow, but ongoing. The extent of occurrence and area of occupancy are both very small. Critically Endangered is the correct assessment for this mainland subspecies.

Global threats

The small population on the mainland that constitutes this subspecies is in part (southern subpopulation) legally protected in the Torrey Pines State Park. However, the small overall size, fewer than 3500 mature trees covering ca. 320ha in two subpopulations, and close proximity to major urban development, put the subspecies highly at risk of destructive events such as fires, pest epidemics and diseases. Trees outside the reserve are often not adequately protected from development; they are sometimes incorporated in urban landscaping and sometimes felled (personal obs., 1992). Urbanisation outside the reserve is ongoing, with expanding housing projects encroaching on the population of Torrey pines. The permits required to fell a tree do not seem to have stopped this happening. It is expected that this will result in continuous, slow loss of mature trees unless all are incorporated in a protected area and a total ban on felling is enforced.

Conservation Actions

One of two subpopulations is protected within a specially created reserve (Torrey Pines State Park), where collecting and other activities detrimental to the pines are strictly prohibited and regulations enforced. The Torrey Pine is protected by a city tree ordinance in Del Mar, near the native habitat, and construction projects and citizens need an approved permit before they can remove any. It is strongly recommended to create a reserve for as many trees as possible in the second (northern) subpopulation, and stop housing projects from encroaching on the natural population of this pine.