Podocarpus pallidus N.E.Gray

Podocarpaceae

Endemic to the Tongan Islands in the southwestern Pacific where the small populations on two islands are at risk from stochastic destructive events

Associated Names:

uhiuhi

Distribution

Endemic to the Tongan Archipelago in the southwestern Pacific. Very restricted, as far as known only on the island of ‘Eua and the islands of 'Uta Vava'u (Franklin, 1999).

This species appears to occur on two islands, 'Eua and 'Uta Vava'u. No collections are known from the other islands including Tongatapu, Tofua and Late. As this species is a minor component in broad-leaved tropical forest, it is assumed there are fewer than 500 mature trees on each island. There is no information about possible decline.

Habitat and Ecology

Podocarpus pallidus occurs in tropical low forest, dominated by angiosperms. This species is usually scattered in forest patches along the plateau escarpment and in ravines or gullies of two islands in the Tonga Archipelago situated some 325km apart. It has been found on limestone cliffs on Uta Vava'u and occurs from around 50 to 250m above sea-level.

Conservation Status

Global status

Vulnerable D2

Global rationale

The extent of occurrence (EOO) of 17.5km2 has here been calculated separately for the two islands that lie some 300km apart in the Pacific Ocean. The area of occupancy (AOO) of 2.25km² is derived from a smaller grid cells due to the estimated small population and the fact that there are virtually no large areas of natural vegetation on the islands in which this species occurs. Both EOO and AOO are this well within the threshold of CR but no decline of the population is currently evident. It therefore meets only criterion D for Vulnerable. This was also the conclusion of the previous assessment for the IUCN Red List, under the project to assess DD conifers (Farjon et al., 2006).

Global threats

The small size of the two known sub-populations make this species vulnerable to stochastic destructive events. The island of ‘Eua is mostly flat and has two villages and a pattern of old square fields (garden agriculture) interspersed with (semi-) natural vegetation. From aerial images on Google Earth it appears that this situation may be stable. A similar situation occurs on the Vava’u Group, also mostly flat islands, but there are more villages. There seem to be many patches of (semi-) natural vegetation interspersed with old and new fields.

Conservation Actions

Field surveys are required to establish (sub)population size and age structure in the population; depending on necessity one or more protected areas should also be established. A small proportion of the sub-population on ‘Eua Island may occur in the national park of that name, within a strip of bushy forest below the escarpment on the east coast.